Search

[Display omitted] • Thermoelectric properties of F4TCNQ-doped benzodithiophene-thienothiophene copolymers. • Partial or integer charge transfer states between the polymers and dopant. • Significant influence of polymer aggregation on polymer-dopant interaction. • Correlation between the nature of charge transfer states with thermoelectric parameters. Organic thermoelectric materials have been gaining increasing interest due to their capacity to convert waste heat into electricity. This study explores the impact of doping-induced charge transfer states on the thermoelectric properties of benzodithiophene-thieno[3,2-b]thiophene-based polymers (PBDTTT) doped with 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Detailed structural, optical, and electrical analyses were conducted on two specific polymers, PBDTTT:C (P1) and PBDTTT:EFT (P2). The investigation revealed distinct doping behaviors: P1 formed a partial charge transfer (PCT) complex, whereas P2 predominantly formed an integer charge transfer (ICT) complex. This distinction is attributed to the inherent structural differences and varying aggregation capabilities of the polymers. As a result, P2 exhibited enhanced electrical conductivity and a superior thermoelectric power factor compared to P1. This study emphasizes the critical role of polymer aggregation and charge-transfer mechanisms in optimizing the thermoelectric performance of conjugated polymers. It offers valuable insights for the development of efficient thermoelectric materials and the advancement of energy conversion technologies. [ABSTRACT FROM AUTHOR]

The internally formed Ov-ZAF with spatially separated Ov-ZAF can reduce 498.3 mg/g of U(VI) in 100 ppm uranium solution in 200 min with a reduction efficiency of 99.8 %. [Display omitted] • It has excellent solar photocatalytic reduction of uranium and antibacterial properties. • Homogeneous flower-like microspheres of O v -ZAF were synthesized. • Z- Scheme heterojunction structure promotes photogenerated carrier migration. • O v -ZAF surface energy band alignment promotes separation of electrons and holes. • This strategy opens up new ideas for the design of specific nanocatalysts. Designing an efficient reduction of soluble U(VI) to insoluble U(IV) is a challenge, and efficient electron-hole transfer efficiency is the key to the conversion of U(VI) to U(IV). Herein, defective transition metal sulfide (O v -ZAF) Z-Scheme tandem heterojunctions with spatial separation were synthesized using an in situ self-assembly method. O v -ZAF has excellent electron-hole separation, stabilized reactive active sites, and excellent visible light absorption. O v -ZAF is able to realize the photocatalytic U(VI) reduction reaction (URR) and water oxidation reaction (WOR) synergistically. The results showed that O v -ZAF was able to reduce 498.3 mg/g of U(VI) in 100 ppm uranium solution for 200 min, with a reduction efficiency of 99.8 %. O v -ZAF showed excellent reduction ability in a variety of uranium-containing waste solutions as well as in real seawater. In addition, O v -ZAF is capable of generating reactive oxygen radials (ROS) and has excellent antimicrobial activity against Escherichia coli, Staphylococcus aureus and Pseudoalteromonas xiamen. Oxygen vacancies and tandem components can tune both occupied and unoccupied orbitals near the Fermi level of O v -ZAF. This work provides a possibility of efficient uranium reduction engineering through tunable compositions and electronic structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Series of La-Ni/Al 2 O 3 catalysts were synthesized by a facile co-precipitation method. • La-Ni/Al 2 O 3 catalysts exhibited superior catalytic hydrogenation activity for LOHCs. • The ultrafine nanoparticles were formatted with balanced dispersion of acid sites. • The temperature significantly influenced the Ni and NiO content of as-prepared catalysts. • DFT calculations revealed a significant charge accumulation at the Ni-NiO interface. The development of cost-effective, efficient and stable catalysts for liquid organic hydrogen carriers (LOHC) is crucial for large-scale hydrogen storage. Herein, we introduced La species into Ni/Al 2 O 3 via co-precipitation method, yielding La-Ni/Al 2 O 3 catalysts. Such catalysts demonstrated exceptional performance and durability in hydrogenating various LOHC candidates. Their hydrogenation capabilities surpassed most state-of-the-art and commercial catalysts, attributing to the homogenous formation of ultrafine nanoparticles induced by La species, prevention of producing unfavorable components, optimal microstructural distributions and balanced dispersion of acid sites. DFT calculations indicated that Ni-NiO(0 0 2) interface played crucial roles in modulating the electron deficiency of surface Ni atoms. The synergistic effect of Ni0-Niδ+ shifts the d -band center of Ni closer to the Fermi level, enhancing the catalyst's adsorption capacity of intermediates and achieving higher activity toward activation of benzene and pyrrole ring, therefore leading to rapid and deep LOHC hydrogenation. The resultant catalysts exhibited great potentials for industrial applications. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, SnS 2 -SnO 2 -CNTs heterostructure was constructed to modify both the separator and cathode, which promotes the movement of the P band center of the tin atom to the Fermi level, realizing the association process of adsorption, capture, and conversion of LPSs, thus achieving high-performance Li-S battery. • SnS 2 -SnO 2 heterostructure is designed to modify both separator and cathode for Li-S battery. • The formation of heterostructure regulates the movement of the P band center of Sn. • SnS 2 -SnO 2 reduces the deposition barrier of Li 2 S and promotes redox kinetics. • Superior performance achieved under high rate or high S loading. Lithium-sulfur batteries (LSBs) are considered a strong contender for the new-generation secondary energy storage system due to their high capacity and energy density. However, the sluggish reaction kinetics and the shuttle effect of lithium polysulfides (LPSs) severely hinder the cycle stability. The robust design of both the separator and cathode exhibit an effective role in restricting the shuttle effect and accelerating redox kinetics through the LPSs trapping and catalyzing effect. In this paper, a CNT-modified tin sulfide and tin oxide (SnS 2 -SnO 2 -CNTs) heterostructure was constructed as a multifunctional catalyst to modify both the separator and cathode to achieve high-performance LSBs. The formation of SnS 2 -SnO 2 heterostructure promotes the movement of the P band center of the tin atom to the Fermi level, which realizes the association process of adsorption, capture, and conversion of LPSs, thus effectively suppressing the shuttle effect. The SnS 2 -SnO 2 heterogeneous interface can also reduce the deposition barrier of Li 2 S, thus greatly promoting the redox kinetics. Together with the improved electron transfer, the resulting LSBs with the robust electrode and separator exhibit superior electrochemical performance with a high initial capacity of 930.2 mAh g−1 at 1 C with a high sulfur loading of 4.3 mg cm−2 and a remarkable capacity of up to 580.3 mAh g−1 at an ultrahigh rate of 7.4 C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Utilized a simple hydrothermal method to create PN junction composites. • Proved enhanced Faradaic activity via charge redistribution at interfaces. • Reduced band gap enhanced LDH material conductivity. • Investigated charge transfer pathways during charging/discharging. Heterostructure materials, owing to their unique interfaces, robust structures, and synergistic effects, are increasingly garnering attention for their potential to enhance the energy/power output and lifespan of energy storage devices. Nonetheless, the intricate relationship between the band theory of heterostructures and their design strategies still demands further exploration. In this study, a binder-free NiCo 2 O 4 @NiCoAl-layered double hydroxide (LDH) PN junction cathode was constructed through a straightforward hydrothermal reaction. Extensive characterization and first-principles calculations have substantiated that the redistribution of charge within the space charge region considerably boosts the Faradaic activity and augments the conductivity of the LDH component, demonstrating an impressive specific capacitance of 1434.0 C g−1. Furthermore, the analysis focusing on the width of the space charge region has shed light on the charge transfer mechanism during charging and discharging, thereby validating the efficacy of the PN junction material design strategy. This research underscores the pivotal role of semiconductor theory in heterostructures and illuminates the potential of Faradaic PN junction composite materials in battery-type energy storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • La(Cu 0.2 Cr 0.2 Ni 0.2 Fe 0.2 Co 0.2)O 3 with appropriate Fermi level can improve mobility. • La(Cu 0.2 Cr 0.2 Ni 0.2 Fe 0.2 Co 0.2)O 3 with transition metals synergism improve injection. • La(Cu 0.2 Cr 0.2 Ni 0.2 Fe 0.2 Co 0.2)O 3 can promote carrier drive by lattice driving force. • WO 3 with surface hydrophobicity can achieve a decent self-cleaning performance. The self-cleaning transparent pn junction in CuAlO 2 /WO 3 via high entropy perovskite oxide La(Cu 0.2 Cr 0.2 Ni 0.2 Fe 0.2 Co 0.2)O 3 transition layer is prepared by the multiple sol–gel-annealing method. The CuAlO 2 /La(Cu 0.2 Cr 0.2 Ni 0.2 Fe 0.2 Co 0.2)O 3 /WO 3 pn junction exhibits high transmittance of ∼85–90 %, remarkable photovoltaic enhancement of ∼6.2 × 103 folds (PCE of ∼1.19 %), stable output in 5 months' cycle and decent self-cleaning performance via simple cleanout. It can be mainly attributed to the modification of multifunctional high entropy perovskite oxide solid solution La(Cu 0.2 Cr 0.2 Ni 0.2 Fe 0.2 Co 0.2)O 3 nanoparticles, besides the appropriate Fermi level and high quantum yield can improve the carrier kinetic equilibrium for balancing transparency and photovoltaic conversion, it can also improve extra carrier injection by the charge compensation and promote carrier driving by the lattice driving force, meanwhile achieving self-cleaning via the hydrophobicity of WO 3. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atomic doping combine surface ion graft is first time used to boost photocatalytic. • Atomic doping effect is systematically studied for the optimal heteroatomic doping. • Atom doping and surface ion graft synergistically manipulate photocharges separation. The synergistic implementation of atomic-level charge separation strategies for bulk–surfaces is a meaningful study that fundamentally addresses the shortcomings of single materials. Here, we report for the first time the atomic-level engineering of atomic doping in combination with surface ion grafting, which can be coordinated to significantly facilitate photocatalytic H 2 evolution. More impressively, the study systematically investigated the atomic doping effects of Fe, Co, Ni and Cu atoms, and analyzed the conditions for optimal doping with experimental and theoretical calculations. The doping of variable valence Cu atoms leads to the emergence of newly occupied electronic states at the Fermi energy level, which effectively improves the carrier separation. The X-ray absorption spectroscopy (XAS) results verified the precise coordination environments of the doped Cu atoms, as well as confirmed the solid grafting of Ni ions on the catalyst surface. Furthermore, the hydrogen production rate of 1.2 % Cu–Zn 0.67 Cd 0.33 S–0.5 wt% Ni reached 38.17 mmol/g/h, corresponding to an apparent quantum efficiency of 35.5 %, which is 82.8 times higher than that of pure ZCS. Besides, the H 2 production rate can reached 118.73 mmol/g/h without cooling. Meanwhile, the synergistic strategy of manipulating the bulk and surface photo-charges of Zn 0.67 Cd 0.33 S also effectively enhances the photothermal effect and further improves its photocatalytic performance. This work provides different inspirations for bottom-up design of efficient photocatalysts to achieve synergistic facilitation strategies. [ABSTRACT FROM AUTHOR]

[Display omitted] • SACs with lower Fermi levels exhibit higher binding affinities towards sulfur species. • SAC Fermi level correlates with the electrocatalytic activity in Li−S batteries. • Ni SACs feature the lowest Fermi levels among the catalysts tested and show the highest electrocatalytic activities. Single-atom catalysts (SACs) have emerged as promising candidates for promoting sulfur cathode kinetics. Despite the growing popularity, the literature is devoid of general guidelines for predicting the electrocatalytic effects exerted by novel SACs. Herein, a series of SACs immobilized on N-doped graphene were prepared from metal (Mn, Ni, Cu, or Zn) porphyrins. The Fermi levels of the catalysts were found to be inversely correlated with their electrocatalytic effects. For example, the Ni-based SACs exhibited the lowest Fermi level but showed the strongest binding affinity to sulfur. As a result, Li−S cells containing Ni SACs exhibited a high specific capacity (10.0 mA h cm−2 at 0.05 C), excellent cycling stability (6.7 mA h cm−2 at 0.1 C after 100 cycles) and other remarkable performance metrics even at a high sulfur loading of 9.6 mg cm−2. The methodology offers a way to evaluate the catalytic activities of SACs rapidly and efficiently, particularly in electrocatalytic systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interfacial electronic structure of metal-support is regulated by heteratom doping. • N/S doping promotes the oxidation of Pt-Lewis acid center to a higher valence state. • S atom re-doping causes the d-band center of Pt to shift upward towards Fermi level. • High content of Ptx+ sites enhance the binding of Pt-Lewis acid to *OOH intermediate. • PtNi@N,S-HMCS with more Pt-Lewis acid shows high ORR activity and 4e- selectivity. Elucidating the mechanism of metal-support interface domain regulation is crucial for designing efficient fuel cell electrocatalysts. Herein, we propose an emerging strategy to enhance oxygen reduction reaction (ORR) activity and selectivity by regulating the Lewis alkalinity of carbon support to adjust the Lewis acidity of metal sites. The experimental results and density functional theory (DFT) simulations show that the introduction of N/S atoms into the carbon support structure will break the charge balance of the carbon skeleton and effectively regulate the charge distribution in the Pt-carbon interface domain, thus promoting the oxidation of the Lewis acid Pt atoms to a higher valence state Ptx+, so as to optimize the adsorption energy of oxygen-containing intermediates. Moreover, Bader charge analysis also verifies that N,S-HMCS, as a Lewis base, can receive more electrons from the Pt sites of Lewis acid, and the electron loss at Pt sites caused by N,S-HMCS strengthens interfacial electron effect. Meanwhile the strong electron adsorption ability of N/S atoms causes the d-band center of Pt atom orbital to shift upward to the Fermi level, which strengthens the binding of metal Lewis acid Pt sites with *OOH intermediates, and improves the 4-electron transfer mechanism. This research reveals the direct role of Lewis acid sites in ORR of fuel cell cathode, and provides a feasible way to guide the design of electrocatalysts with Lewis acid/base double centers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Doping Ni/Co to MoS 2 shifts d-band center to Fermi level, getting more CO adsorbed. • The d-electrons transfer from Ni/Co to Mo occurred that promoted S vacancies. • The rate-limiting step for CO methanation on Ni or Co doped MoS 2 was CO + H→*CHO. The catalyst modified by the difference of transition metal d orbital electrons is a promising strategy to promote its catalytic activity, which has been extensively studied in heterogeneous catalysis. Herein, Ni and Co transition metals were used to modify the MoS 2 catalyst and promote activity for sulfur-resistant CO methanation. Characterization results indicated that Ni or Co atoms could be successfully doped into the edge-site of MoS 2 , which generated more S-vacancy at Mo-edge site and enhanced sulfur-resistant CO methanation activity. The roles of Ni and Co doping in improving activity were explored based on DFT calculation. It was found that Ni or Co could modify the electronic structure, weaken the strength of their interaction with edge S atoms and promote the spontaneous formation of more S vacancies at Mo edge sites. This leads to enhancing the adsorption of CO and weakening the bonding energy between C-O, which implied the facilitation of CO hydrogenation. Moreover, the modified Ni(Co)-Mo-S active sites facilitate the rate-determining step of CO hydrogenation activation to form *CHO species, which contributes to the enhanced activity for sulfur-resistant CO methanation. This work provides an attractive method for modifying MoS 2 catalysts for sulfur-resistant CO methanation. [ABSTRACT FROM AUTHOR]

• 4-Imidazoleethylamine is used to induce p to n-type transition at CsPbI 3 surface. • Back-surface field is established at CsPbI 3 surface region to inhibit interfacial energy loss. • High efficiency of over 20% is obtained in inverted CsPbI 3 solar cells. Energy loss at perovskite/electron transporting layer (ETL) interface is one key reason limiting the efficiency of inverted CsPbI 3 perovskite solar cells (PSCs). Here we introduce a back-surface field in inverted PSCs through 4-Imidazoleethylamine (4-IEA) treatment to mitigate such interfacial energy loss. 4-IEA treatment will upshift the Fermi level of CsPbI 3 surface and thus induce an extra back-surface field aligning with the built-in potential of inverted PSCs, thus reducing energy loss and facilitating electrons extraction at the CsPbI 3 /ETL interface. In addition, 4-IEA can passivate interfacial defects owing to its Lewis base-acid interaction with CsPbI 3. As a result, power conversion efficiency (PCE) of 20.22% is achieved in inverted CsPbI 3 PSCs. Furthermore, PSCs with 4-IEA also exhibit good operational stability, retaining over 70% of initial efficiency after maximum power point (MPP) tracking at high temperature of 65 ℃ for 200 h. [ABSTRACT FROM AUTHOR]

• Co nanoparticles are embedded in N-doped carbon nanotubes (Co-N-carbon nanotubes). • A further thermal condensation between Co-N-carbon nanotubes and g-C 3 N 4 nanosheets occurred to form Co/g-C 3 N 4 junctions. • The Co/g-C 3 N 4 junctions with Schottky barrier existed between the carbon layer coated Co nanoparticles and g-C 3 N 4 nanosheets. • The Schottky junction composites shows a photocatalytic H 2 O 2 generation efficiency of 3618 μmolL−1h−1 without co-catalysts. • NO removal rate of 62 % is higher than that of the commercial P25 (TiO 2). Co nanoparticles are embedded in N-doped carbon nanotubes (Co-N-carbon nanotubes) using combinations of mechano-chemical pre-treatment and thermal polymerization process (at 760 °C). A further thermal polymerization process done on these Co-N-carbon nanotubes and ultrathin graphitic carbon nitrate (g-C 3 N 4) leads to the formation of Co nanoparticles (coated with carbon layers) embedded g-C 3 N 4 nanosheets composite, along with the disappearance of carbon nanotube morphology on the material. The Co/g-C 3 N 4 junctions are constructed with a Schottky barrier formed between the carbon layer coated Co nanoparticles and the g-C 3 N 4 nanosheets. The presence of carbon layers in the composite system facilitates transport of photogenerated electrons at the Fermi level of Co, which results in enhanced photocatalytic H 2 O 2 generation and NO oxidation performances of the composite material in visible light irradiation condition with excellent cyclic stability. The Schottky junction composites constructed using optimized preparation conditions in case of no co-catalyst incorporation shows a photocatalytic H 2 O 2 generation efficiency of 3618 μmolL−1h−1 which is about 1000 times of that of pristine g-C 3 N 4 nanosheets. A NO removal rate of 62 % (higher than that of the commercial P25 (TiO 2)) is also observed. These results provide possible approaches on constructing advanced photocatalysts for energy and environmental applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel dual S-scheme heterojunction CeO 2 /g-C 3 N 4 /Bi 2 O 4 was first reported. • The dual S-scheme interfacial charge transfer mechanism was discussed via in situ XPS. • CeO 2 /g-C 3 N 4 /Bi 2 O 4 shows excellent activity and stability with TC removal rate of 94 %. • Three possible degradation pathways of TC were proposed based on LC-MS analysis. • The environmental factors have less influence on photocatalytic degradation of TC. Constructing dual S-scheme heterojunction, as one kind of new strategy for the reinforcement of photocatalytic property, shows significant advantages in facilitating the migration of photoinduced charges and achieving high redox potentials. Herein, a novel double S-scheme heterojunction CeO 2 /g-C 3 N 4 /Bi 2 O 4 was designed and synthesized successfully. The photodegradation of tetracycline (TC) over CeO 2 /g-C 3 N 4 /Bi 2 O 4 was carried out under the irradiation of visible light. The double S-scheme interfacial charge transmission mode of CeO 2 /g-C 3 N 4 /Bi 2 O 4 was investigated according to Fermi level, band structure, and the in-depth analysis of in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) and electron spin resonance (ESR) spectra. The CeO 2 /g-C 3 N 4 /Bi 2 O 4 exhibits excellent catalytic activity with a high TC removal efficiency of 94 % and a remarkable mineralization efficiency of 51 %. The rate constant (0.05811 min−1) of TC degradation for CeO 2 /g-C 3 N 4 /Bi 2 O 4 is 12.9, 7.8, 4.3, 2.2, and 3.1 times those for g-C 3 N 4 , CeO 2 , Bi 2 O 4 , g-C 3 N 4 /Bi 2 O 4 and CeO 2 /g-C 3 N 4 , separately. The prominently boosted activity may be due to two factors. Firstly, the successful creation of the double S-scheme electron migration channel greatly boosts the transmission of photogenerated carriers, represses the recombination of electrons with holes, and ensures the strongest redox potential of CeO 2 /g-C 3 N 4 /Bi 2 O 4. Secondly, the introduction of Bi 2 O 4 with excellent visible-light absorption broadens the optical absorption region of CeO 2 /g-C 3 N 4 /Bi 2 O 4. Additionally, the influence of the typical environmental factors (pH, inorganic anions, cations, and natural humus) on the photodegradation of TC was explored. The three probable pathways for TC degradation were inferred via analyzing intermediates. The current work offers a novel outlook for enhancing the activity of ternary heterojunction photocatalysts applied in environmental restoration. [ABSTRACT FROM AUTHOR]

• The effective mass is increased firstly by shifting the Fermi level. • The PF is enhanced by increased σ and maintained α. • The PF and κ are simultaneously improved by a synergistic effect via Bi doping. • Bi substitution on Sb-site is different from conventional substitution on cations. Recently, extensive research has been done to explore the potential thermoelectric performance of p-Type Zintl compounds AB 2 Sb 2 (A = Ca, Yb, Eu, Sr, Mg; B = Zn, Mn, Cd, Mg), mainly focus on A-site substitution and/or B-site substitution effect. Herein, we report that both power factors and thermal conductivities are simultaneously optimized to increase ZT values via substitution of Sb atoms with the isoelectronic Bi atoms in YbZn 2 Sb 2− x Bi x compounds. We found that the power factor could be enhanced by 27%, as a result of improved electrical conductivities and the maintained Seebeck coefficients. The former is obtained from an increase of carrier density through a shift of Fermi level via Bi doping, which is supported by XPS analysis. The Seebeck coefficients are maintained due to the increased effective mass. Moreover, the lowest lattice thermal conductivity (0.47 Wm−1 K−1 at 723K) is below the lattice thermal conductivity limit due to enhanced phonon scattering via Bi-doping, which is analyzed by the Callaway model. Benefiting from the synergistic effect, the ZT of Bi-doping samples are significantly enhanced compared with that of the pristine one. These results probably offer a synergistic strategy to enhance ZT for p-Type Zintl compounds AB 2 Sb 2 and other high-efficiency thermoelectric materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ge-Ti codoping synergisticly suppresses bulk and surface charge in the Fe 2 O 3 photoanodes. • AlOOH modification elevates the flat-band potential and enhances charge separation. • Secondary growth layer and NiFeO x cocatalyst effectively reduce onset potential. • Photocurrent density of 3.46 mA cm−2 at 1.23 V RHE and ABPE of 0.51% were achieved. • The Cat/Al/SG/Ge-Ti shows long-term stability of less than 10% decay after 20 h. The poor charge separation efficiency is the main limiting factor of the α-Fe 2 O 3 photoanode for photoelectrochemical water splitting. In this study, we have discovered that the incorporation of Ge-Ti codoping and AlOOH modification strategies can greatly enhance the charge separation efficiency of the α-Fe 2 O 3 photoanode. By introducing the Ti element, which possesses high conductivity, and further enhancing the charge transfer through Ge doping, we have achieved a synergistic inhibition of charge recombination in the Ge-Ti codoped α-Fe 2 O 3. Additionally, the introduction of AlOOH through modification has led to an increase in the interface band bending, thereby enhancing charge separation by elevating the Fermi band level. Furthermore, through the secondary growth (shorted as SG) of undoped α-Fe 2 O 3 and the incorporation of a NiFeO x cocatalyst, we have successfully adjusted the surface states and reduced the onset potential. Through the collaborative efforts of Ge-Ti codoping, SG, AlOOH modification, and NiFeO x catalysis, we have sequentially optimized the performance of the α-Fe 2 O 3 -based photoanode, resulting in an impressive photocurrent density of 3.46 mA cm−2 at 1.23 V RHE , as well as a low onset potential of 0.65 V RHE. [ABSTRACT FROM AUTHOR]

• Sb 2 S 3 NRs with high carrier transport were prepared by a novel epitaxial growth. • Novel Tm3+ doped strategy weakens the Fermi level pinning effect of Sb 2 S 3. • The enhanced PEC performance is attributed to the S-scheme mechanism. • The injection efficiency of the optimized photocathode was 81.7%. With the advantages of high absorption coefficient, non-toxicity and low cost, Sb 2 S 3 shows great potential as a narrow bandgap photocathode in the field of PEC hydrogen production. However, the separation and transportation of photogenerated carriers in the reported Sb 2 S 3 photocathode are inefficient due to its anisotropy and the Fermi level being pinned by deep-level defects. Therefore, Tm3+ doped Sb 2 S 3 nanorods with the selective carrier transport orientation were epitaxially grown on SnSe 2 film by a simple hydrothermal strategy to modulate the defect property of Sb 2 S 3 , optimize carrier transportation and separation efficiency, and improve the PEC performance of photoelectrodes. Experimental results showed that the doping of Tm3+ weakening the Fermi level pinning while achieving the conversion of Sb 2 S 3 to n-type conducting property. The S-scheme heterojunction formed by Tm3+ doped Sb 2 S 3 nanorods labeled as Sb 2 S 3 : Tm3+ and SnSe 2 nanosheets provided a stronger driving force to optimize carrier interface transportation. The photocurrent density (−0.91 mA cm−2) is increased about 18 times compared to the pristine Sb 2 S 3 photocathode. This work developed an effective doping strategy to weaken the Fermi level pinning and provided a novel idea for the epitaxial growth of Sb 2 S 3 nanorods to optimize the carrier transportation. [ABSTRACT FROM AUTHOR]

• Fe-Mn bimetallic phosphorus trisulfide heterostructure was firstly synthesized. • The frame structure of FeMnP 2 S 6 is conducive to holding and trapping the sulfur. • The strong electrical coupling on Fe 2 P 2 S 6 surface enhances kinetics. • D-band center shifts to Fermi level via introducing Mn 2 P 2 S 6 , promoting catalysis. Monofunctional host materials of lithium-sulfur (Li-S) batteries are inadequate to simultaneously address the complex issues including "shuttle effect" and sluggish redox kinetics. Herein, iron and manganese bimetallic phosphorus trisulfide (Fe-MnP 2 S 6) with heterointerfaces and a semi-open frame structure was synthesized as a multifunctional host material for Li-S batteries. Theoretical calculations suggest that due to the strong electronic coupling effect, electrons migrate from the MnPS 3 layer to the FePS 3 layer, accelerating charge and ion transfer on the surface of FePS 3. The d-band center of metal atoms shifts towards the Fermi level through the introduction of Mn 2 P 2 S 6 , enhancing the interaction with polysulfides. Moreover, the frame exhibits excellent structural stability and physical limiting ability of sulfur. As a result, the cell with Fe-MnP 2 S 6 delivers impressive electrochemical performance and redox kinetics, including a capacity of 1388 mAh/g at 0.2C, a rate performance of 850 mAh/g at 4C and a capacity attenuation rate of 0.028 % per cycle over 1,000 cycles at 1C. Through meticulous structural design and optimal composition adjustments, our work explores the mechanism of metal phosphorus trisulfides (MPS 3) in Li-S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel 2D/2D BiOCl/BiOIO 3 heterojunction with oxygen defects has been fabricated. • The oxygen defect enhanced the charge transfer and visible light absorption capacity. • The enhanced internal electric field accelerated the charge transfer. • Photocatalytic activities for organic pollutants removal have significantly enhanced. It is particularly significant that the enhancement of charge transfer efficiency and visible light absorption ability on the removal of organic pollutants by semiconductor photocatalysts, for which the interfacial electric field modulation and defect engineering are the linchpins. Herein, we first report the introduction of oxygen defects to regulate interfacial electric field assisted by nature-derived reduction method with green tea extracting solution. Interestingly, the continuously adjustable visible light response, oxygen defect content, and internal electric field intensity for the as-designed heterojunctions are achieved by simply tuning the concentration of the extract solution. The extract modification BiOCl/BiOIO 3 heterojunctions exhibit more efficient photogenerated charge transfer, stronger light-harvesting capacity, and superior photocatalytic performance for ciprofloxacin removal compared with the original BiOCl/BiOIO 3 heterojunctions. Deep insights into synergistic promotion of steering charge transfer from the perspectives of oxygen defect introduction and internal electric field modulation are unfolded, exclusively shedding new light on the green bio-inspired tactics for promoting the photoelectrochemical property of semiconductor photocatalysts. [ABSTRACT FROM AUTHOR]

• The wet-chemical method successfully achieved uniform Mg–doping in the bulk phase. • Mg2+ doping further enhanced the cyclic stability of FNCM. • Mg2+ doping suppressed the layer structure collapse and H2–H3 phase transition. • Mg2+ doping enhanced the dynamic migration process of ions and electrons. • The mechanism of Mg2+ doping to improve internal structure stability was explored. Ni-rich layered LiNi x Co y Mn 1− x − y O 2 (x ≥ 0.6) cathodes suffer from the extreme structural instability of their surface and interior owing to high Ni content. Although the structural design of full-concentration-gradient (FCG) better solved their surface instability, the deterioration of internal structure caused by the higher Ni content in the interior of particles became more prominent, and seriously limiting the cycle performance of FCG Ni-rich layered cathode materials. In this study, a strategy for the internal structure regulation by magnesium doping was proposed to overcome the internal structure instability of FCG Ni-rich layered LiNi 0.80 Co 0.05 Mn 0.15 O 2 (FNCM) cathode materials. The experimental results and DFT calculations revealed that Mg2+ doping not only suppresses the layer structure collapse and H2–H3 phase transition but also improves the electronic conductivity by enhancing the free electron number near the Fermi level. The enhancement of the internal structure stability and dynamic migration process of ions and electrons contributed to improving cycle stability. As a result, the 0.02 mol% Mg2+ doped sample delivers an outstanding initial discharge specific capacity of 182.6 mAh g−1 at 1C with a satisfactory capacity retention of 90.7% after 200 cycles, which is higher than that of the original sample (capacity retention of only 81.3%). Most importantly, it still exhibits excellent capacity retention of 82.5% and 83.3% at a high cutoff voltage (4.5 V) and a high temperature (50 °C) after 200 cycles, respectively. These results indicated that magnesium doping is an attractive strategy to further improve the cycle stability of FCG Ni-rich cathode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • W-NiCo 2 O 4 -2 hierarchical porous sheets facilitate mass transport. • W6+ doping optimizes the adsorption of oxygen intermediates. • The optimized electron structure promotes the formation of MOOH (M = Co, W). • W6+ doping enhances the intrinsic conductivity of NiCo 2 O 4. Limited specific surface area, active site amount, and intrinsic conductivity inhibit spinels' electrocatalytic oxygen evolution reaction (OER) activity. Herein, we proposed a high-valence oxyanion exchange strategy for preparing hierarchical sheet-like W-NiCo 2 O 4 -2 spinel OER electrocatalyst, which exhibits favorable activity (306 mV overpotential@10 mA cm−2) and durability in 1.0 M KOH solution, and shows an application prospect in a home-made anion exchange membrane (AEM) electrolyzer. BET results showed that the hierarchical structure increased specific surface area and corresponding edge active sites amount, accelerated mass transport and charge transfer. XPS, ex-situ Raman spectroscopy, and HRTEM characterizations dispicted that W6+ doping optimizes e g orbital electron filling and promotes M−OOH (M = Co, W) active species generation. DFT calculations reveal that W6+ doping modulates the adsorption of oxygen intermediates, improving the reaction kinetics, and increasing the density of electronic states nearby the Fermi level, thus enhancing conductivity. This work provides a universal pathway for modulating spinel-based OER electrocatalysts. [ABSTRACT FROM AUTHOR]

• In situ growth of BiVO 4 nanoparticles on UiO-66-NH 2 octahedral surfaces by hydrothermal synthesis. • The Z-scheme charge transfer pathway of BVO/U6N composite was further demonstrated by in-situ XPS. • The superoxide radical is the key reaction species in photocatalytic system. • Photocatalytic conversion of thioanisole to sulfoxide showed excellent yields and selectivity by BVO/U6N under visible light. The photocatalytic efficiency can be enhanced by constructing Z-scheme heterostructures. However, there is still a lack of comprehensive and direct evidence regarding the charge transfer pathway and mode during the photocatalytic process. A composite photocatalyst BiVO 4 /UiO-66-NH 2 (BVO/U6N) was prepared by in-situ loading BiVO 4 nanoparticles onto the surface of UiO-66-NH 2 using a hydrothermal method. This catalyst effectively promotes the photocatalytic conversion of thioanisole to sulfoxide. The differences between BiVO 4 and UiO-66-NH 2 in band structure and Fermi energy level enable the composite to act according to the Z-scheme charge transfer pattern, which significantly enhances charge separation efficiency. In-situ X-ray photoelectron spectroscopy (in-situ XPS) combined with DFT calculation confirmed the transfer of electrons from UiO-66-NH 2 to BiVO 4 , driven by an internal electric field (IEF) upon hybridization. This demonstrates the formation of a Z-scheme photogenerated charge transfer pathway in the BVO/U6N composite. The direct Z-scheme system significantly enhances the carrier redox, resulting in a sulfoxide yield of 95.21% for the optimized sample in methanol, which is 5 times and 4.1 times higher than that of UiO-66-NH 2 and BiVO 4 , respectively. BVO/U6N exhibits efficient photocatalysis and selectivity towards various substrate sulfides, making it a highly promising heterogeneous photocatalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • The few-layer defective δ-MnO 2 was developed by hydrothermal with CTAB and KMnO 4. • As the current increases by 50-fold, δ-MnO 2 -CTAB shows ultra-high rate-capability. • The kinetics diffusion mechanism of the sample was analyzed by DFT calculations. δ-MnO 2 nanosheets are promising cathode candidates for supercapacitors because of their cost-effective, environmental protection, and high theoretical capacity. Unfortunately, the commercial application of δ-MnO 2 is hindered by the challenging issues of sluggish diffusion kinetic and poor rate-capability. It is urgent to optimize its kinetics behavior to improve the ion diffusion ability and electronic conductivity. Herein, one-step and one-phase synthesis of few-layer defective δ-MnO 2 nanosheets (named δ-MnO 2 -CTAB) has been developed via a redox reaction between cetyltrimethylammonium bromide (CTAB) and KMnO 4 , and the kinetics storage mechanisms are investigated by DFT calculations. The migration barrier energies of Na in the surface or interlayer of δ-MnO 2 (0 0 1) are reduced significantly with the reduction of layer-number (0.32 eV of 3 layers and 0.04 eV of 2 layers), which is conducive to the Na ion diffusion. Moreover, the generation of defects increases the density of states at the Fermi level of δ-MnO 2 , indicating the improvement of electronic conductivity. Therefore, when the current density is increased 50-fold (1 A g−1 to 50 A g−1), the rate-capability of δ-MnO 2 -CTAB is as high as 77%, exhibiting ultra-high rate-capability. This work unveils the kinetics storage mechanisms in few-layer δ-MnO 2 with defects nanosheets for ultra-high rate-capability supercapacitors. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 0.3-AgI/BiVO 4 exhibits excellent photocatalytic performance. • The band structure was revealed via the CASTEP, and valence band XPS. • The simultaneous photocatalytic oxidation and reduction enhancing mechanism was discussed. Abstract Simultaneous combination of photocatalytic oxidation of tetracycline (TC) and reduction of Cr(VI) over the AgI/BiVO 4 p-n junction photocatalysts were studied systematically. The result showed that the pollutant degradation efficiency of the photocatalyst was greatly enhanced when the system contained both TC and Cr(VI) compared to that containing Cr(VI) or TC alone. It is proposed that the co-existence of oxidizable and reducible species, such as TC and Cr(VI), ensured efficient use of the photoinduced electrons and holes, which leaded high efficiencies for both TC oxidation and Cr(VI) reduction. Among these photocatalysts, the 0.3-AgI/BiVO 4 exhibits excellent photocatalytic activity, which is ascribed to the increased lifetime of the charge carriers confirmed by the result of time-resolved fluorescence emission decay spectra. In addition, seven degradation products of TC were found by GC–MS. Moreover, the band structure of the photocatalyst was obtained by the DFT calculation, VB-XPS spectra and the values of the Fermi level obtained by CASTEP. Finally, simultaneous photocatalytic oxidation and reduction enhancing mechanism over the AgI/BiVO 4 photocatalyst was discussed in detail. The strategy of forming novel p-n junction photocatalyst for both the Cr(VI) reduction and TC oxidation will benefit the development of the other new photocatalysts for the purpose of controlling and improving the environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Homo double Ru 2 /Mo 2 CO 2 was derived via activity, stability, and selectivity screening. • Elucidating the correlation between the d-band structure of metal cation constituting the MXene support and the electron density near the Fermi level of single and homo double atom catalyst. • The change in the activity of single and double atoms supported on the MXene surface originated from the difference in overlap ratio between their d orbital and the p orbital of the N atom in NH 2 adsorbate. In this study, we have engineered the MXene supports to boost the single and homo double atoms of Fe, Ru, and Os for efficient NH 3 production via electrochemical nitrogen reduction reaction (N 2 RR) using DFT calculations. We designed the different MXene surfaces which are composed of nine early transition metals [M 2 CO 2 (M = Cr, Hf, Mo, Nb, Ta, Ti, V, W, Zr)] and examined the activity/stability of single and homo double atoms by calculating the free energy diagram of N 2 RR, dissolution potential, and agglomeration energy. First, we found that the NH 2 adsorption energy is the activity descriptor for representing the NH 3 productivity and the density of state near the Fermi level of the single Ru atom is the important factor in determining N 2 RR activity. Next, our DFT calculation on the descriptor-based computational search for the novel MXene-based catalysts showed that among the chemically and electrochemically stable candidate catalysts, the homo double Ru 2 /Mo 2 CO 2 catalyst showed the highest NH 3 productivity with the high N 2 RR selectivity over hydrogen evolution reaction. In addition, the best Ru 2 /Mo 2 CO 2 catalyst exhibited the intermediate density of state near the Fermi level, leading to the optimal descriptor value (NH 2 adsorption strength) for NH 3 production and in turn the reduction of overpotential for the electrochemical NH 3 production. More fundamentally, we identified that the electron density near the Fermi level of these single or double atoms is closely correlated with the electron structure of the cationic metal atoms constituting MXene supports. Our study highlights the rational design of single and homo double atom catalysts by tuning the property of MXene supports, which provides insight into the key factors in enhancing NH 3 production at ambient conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Understand the key factors for broadening the operating voltage of supercapacitors. • The overpotential of MnO 2 can be modulated by tailoring its Fermi energy level. • The ASC exhibits a wide voltage of 2.4 V and a high energy density of 0.89 mWh cm−2. Despite many advantages of supercapacitors based on aqueous electrolytes, the inherently low operating voltage severely limits their energy density and practical applicability to many applications. Thus, it is a key scientific challenge to broaden the potential window of electrode materials for supercapacitors. Here we report our findings in tailoring the Fermi level of MnO 2 -based electrode by doping with a high-valence Mo6+ ion, thus modulating its overpotential in aqueous electrolytes and potential window. For example, the redox potential of Mo-doped MnO 2 is effectively increased, resulting in a wider potential window. When grown on a carbon support, the specific capacitance of Mo-doped MnO 2 @CC with a mass loading of 15.1 mg cm−2 reaches 3.22 F cm−2 in a wide potential window of 1.2 V. The enhanced performance is attributed to the additional redox behavior induced by the Mo dopant, as confirmed by in situ Raman and ex-situ XPS analyses. When coupled with a C-Ti 3 C 2 T x /WO 3 @CC negative electrode to construct an ASC with a total mass loading of 35.8 mg cm−2, the ASC exhibits a wide voltage window of 2.4 V, demonstrating a remarkable energy density of 0.89 mWh cm−2 at a power density of 2.56 mW cm−2. In addition, the device is operational in a wide operating temperature range of −10 to 50 °C, and a voltage of ∼ 58% is retained after self-discharge for 48 h. This work provides some new insights into the development of aqueous ASC devices of commercial-grade mass loadings with high output voltage, high energy density, and slow self-discharge rates. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2D van der Waals SnS 1−x Se x alloys with tunable Se content are synthesized via the ion-exchanged method. • The cause-and-effect of the energy level with response value for p-type SnS 1−x Se x van der Waals alloys is revealed. • Increasing the gap between E f of alloys and molecular orbital of NO 2 contributes to improving the response value. Understanding the relationship between sensing behavior and energy level is an important prerequisite for providing rational guidance to predict advanced gas-sensing materials and develop design principles. A tunably compositional van der Waals (vdW) alloy SnS 1−x Se x (x = 0.2, 0.4, 0.6, 0.8) that reveals the trend of response value with Fermi level is first reported here, which is prepared by the isoelectronic Se atoms substituting the S atoms of SnS via an ion exchange method. The cause-and-effect of the energy level with response value is disclosed by Kelvin probe force microscopy, which reveals that increasing the gap between the Fermi level of alloys and the molecular orbital of NO 2 by tuning Se content can enhance the response value for NO 2. Compared to a no response to NO 2 for pristine SnS crystals at room temperature, the as-prepared SnS 1−x Se x vdW alloys show a sensitive p-type response, in which the response value reaches 400.3% for SnS 0.6 Se 0.4 alloys toward 20 ppm NO 2 with a short response/recovery time (80 s/140 s). The SnS 0.6 Se 0.4 alloys also have excellent selectivity and good stability. As a basic and crucial step, this work could pave the way to develop the gas sensors of vdW layered crystals with a p-type high-sensitive response, and also could be extended to electronics, sensing, and catalysis fields. [ABSTRACT FROM AUTHOR]

Thermochemical energy storage (TCES) is a promising technology to overcome solar intermittency and volatility. However, weak solar absorption, poor cyclic stability for calcium carbonates, and cost issues for metal oxides hinder the applicability of these materials for thermochemical energy storage. Herein, an advanced, affordable, and effective TCES system is proposed, and the corresponding calcium carbonate-metal oxide synergistic material is designed with improved solar absorption and cyclic stability. The optimum molar ratio is Ca:Co:Mn:Mg = 100:20:7.5:5 for the synergistic material fabricated by the modified sol–gel method, where Ca element plays the primary role in heat storage, Co element serves as the primary optical performance enhancer and secondary heat storage component, and Mn/Mg elements act as the secondary performance modifiers. The solar absorptivity is boosted to ∼ 79.3%, and the heat storage density is 1295 kJ/kg after 30 high-temperature cycles, which are 6 times and 2.2 times higher than those of commercial calcium carbonate, respectively. Homogeneous mixing of modifiers at the microscale and stable, well-developed pore structure are critical factors for cyclic stability enhancement. The change of electronic structure on the Fermi level caused by Co/Mn ion doping is the key to optical absorption improvement, and the promoting amplitude exhibits wavelength dependence. This work expands the limited list of currently available TCES materials and the comprehensive description of optical properties offers guidance for future implementation of TCES materials with high solar absorption in specific wavelengths. [Display omitted] • Cobalt is the principal optical enhancer and auxiliary energy storage element. • Co/Mn/Mg co-doped CaO maintains a porous structure in multiple high-temperature reactions. • Solar absorptivity and thermal capacity of the novel material rise by 6 and 2.2 times, respectively. • The optical absorption as a function of electronic structure is discussed to pave the way for designing TCES composite. [ABSTRACT FROM AUTHOR]

[Display omitted] • The difference in Fermi level between Ru and M x O y results in electron transfer. • The BEF created by the charge transfer facilitates the transfer of the charge. • The electronic structure of Ru was regulated by M x O y. • The interaction between Ru and M x O y improves the stability and activity of Ru. • The porous structure of the catalysts promotes the diffusion of electrolyte. The differences in Fermi levels (E f) can drive the electrons flow across the metal/semiconductor interfaces, resulting in a built-in electric field (BEF) to enhance charge migration. Meanwhile, the induced electron-rich/deficient counterparts can modulate the active sites and reaction steps. In this work, a three-dimensionally ordered macroporous (3DOM) heterostructure with oxygen vacancy (O v) supported by carbon (Ru/M x O y @C, M = V, Nb, Ta) was fabricated. Since the E f of M x O y is higher than that of Ru, an adjustable BEF directed by M x O y towards Ru is generated at the interface. The electron-deficient M x O y can dissociate H 2 O effectively, and the electron-rich Ru favors the desorption of hydrogen intermediates. Both experimental and theoretical results confirm the above conclusions. The Ru/Ta 2 O 5 @C demonstrates superior activity than Pt/C. This work provides new design principles toward efficient electrocatalysts for hydrogen evolution reaction (HER). [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic CoFe@N-GC was designed, prepared and coupled with PMS to degrade BSM efficiently. • CoFe-alloy can improve degradation performance by tuning Fermi energy level density of states. • Synergy between Co and Fe, and N doped in graphitized carbon provide superior catalytic property. • CoFe@N-GC can be reused 15 times due to stable phrase and structure and multi-element synergistic effect. • Possible degradation pathway and catalytic mechanism of CoFe@N-GC/PMS system were proposed. Magnetic CoFe alloy@N-doped graphitized carbon nano-catalyst (CoFe@N-GC) was synthesized by hydrothermal method and chemical deposition method, which could couple with peroxymonosulfate (PMS) to degrade herbicide bensulfuron-methyl (BSM). CoFe alloy nanoparticles were encapsulated in N-doped graphitized carbon yarn-like material, providing strong stability and high corrosion resistance properties of them. Furthermore, CoFe alloy can make great improvement of degradation performance via tuning metal site's intrinsic performance of the Fermi energy level density of states. CoFe@N-GC (k = 0.4 min−1) displayed better catalytic performance than CoFe 2 O 4 (k = 0.14 min−1) because of the intrinsic strengths of each component, synergy between cobalt and iron, doping of nitrogen atoms and graphitized carbon and unique electronic properties. 10 mg·L−1 bensulfuron-methyl was degraded completely by the combination of CoFe@N-GC and PMS within 10 min at pH 7. Magnetic CoFe@N-GC could be separated from solution by an external magnet, thus making convenience to collect catalyst and avoiding second pollution. After 15 recycling use of CoFe@N-GC, the BSM degradation efficiency could still be maintained at 95%. CoFe@N-GC/PMS system exhibited stable degradation ability over a wide pH range (3–8) and displayed strong tolerance to real water samples. The main active species, possible BSM degradation pathways and potential reaction mechanism of CoFe@N-GC/PMS were systematically explored. Thus, our finding can provide an environmental friendly, efficient and easy recycle catalyst to degrade refractory organic matters by PMS activation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A strong built-in electric field was constructed in the NH 2 -MIL-125(Ti)/WO 3-x S-scheme heterojunction. • The oxygen vacancy content of the WO 3-x was manipulated to adjust built-in electric field. • Simultaneous generation of CO and H 2 O 2 from CO 2 and H 2 O was realized. Manipulating the built-in electric field (BEF) is a crucial challenge in the development of efficient photocatalysts, especially for S-scheme heterojunction. Herein, a precisely regulation of the BEF intensity of an S-scheme heterojunction was realized by adjusting the oxygen vacancy (OV) content of the composed oxidation semiconductor (WO 3-x nanosheets). When a moderate OV content was created in WO 3-x , its Fermi level migrated down to the lowest position, resulting in the largest difference in Fermi level with the reduction semiconductor of NH 2 -MIL-125(Ti)(NM), and thus, the strongest BEF-driven NM/WO 3-x S-scheme heterojunction was formed. The augmented BEF improved charge separation and transfer, and the S-scheme mode retained high redox ability. As a result, an efficient simultaneous production of CO (12.57 μmol⋅g−1⋅h−1) and H 2 O 2 (8.41 μmol⋅g−1⋅h−1) from CO 2 and H 2 O in the absence of any electron/hole sacrificial agent was achieved, which was 8.01 and 6.62 times higher compared to that of NM, respectively. This work throws inspiration for regulating BEF to enhance the carrier separation and achieve the simultaneous production from photocatalytic CO 2 reduction. [ABSTRACT FROM AUTHOR]

The metal–metal oxide-support interaction stabilized MoO 4 2- is realized in a mesoporous carbon supported heterogenous Ni 4 Mo/NiMoO 4 structure (NiMoO x @CMK-3) for boosting hydrogen evolution. [Display omitted] • A novel NiMoO x @CMK-3 electrocatalyst is synthesized for promoted HER process and outstanding AEMWE performance. • The ex/in-situ characterization evidence the strong heterointerface inhibits the MoO 4 2- loss. • DFT calculations reveal the optimized heterogeneous NiMoO x possesses a moderate Mo-H* binding energy for HER. Constructing low-cost, high-active and robust heterogeneous hydrogen evolution reaction (HER) electrocatalysts with strong metal–metal oxide-support interaction (SMMOSI) is still an urgent challenge for the development of anion exchange membrane water electrolysis (AEMWE), especially under high current density (e.g., 1 A cm−2). Herein, a hierarchical composite of heterogenous Ni 4 Mo/NiMoO 4 (NiMoO x) nanoparticles (NPs) anchored on a mesoporous carbon CMK-3 (NiMoO x @CMK-3) is designed as a superior electrocatalyst for HER. Significantly, the strong interaction between heterogeneous NiMoO x NPs and CMK-3 supporting matrix effectively stabilize the catalytic active Ni 4 Mo/NiMoO 4 heterostructure by altering the local geometric and electronic structures, leading to maximumly exposure of active sites and promoted electron transfer ability. The optimized electrocatalyst exhibits outstanding HER activity with an extremely low overpotential and Tafel slope of 7 mV@10 mA cm−2 and 27.7 mV dec-1, respectively, and can steadily operate at 100 mA cm−2 for 800 h. More significantly, owing to these HER merits, the AEMWE configuration with NiMoO x @CMK-3 (−) is also designed, resulting in low cell voltage of 1.965 V@1 A cm−2 and negligible degradation over 400 h@1 A cm−2. Further ex/in-situ electrochemical spectra evidence that both the partial combined MoO 4 2- from NiMoO 4 and the newly formed MoO 4 2- originating from dissolved Mo in NiMoO x @CMK-3 could boost the fast generation of polymerized Mo 2 O 7 2- that could effectively accelerate the HER process in alkaline conditions by facilitating the formation of active Mo-H* intermediates. Moreover, theoretical calculation results demonstrate the upshifting of d-band center of Mo toward Fermi level for the heterogeneous NiMoO x and the strong charge distribution between the heterointerface could optimize adsorption free energies of H* (ΔG H*) on the surface of Mo atoms. [ABSTRACT FROM AUTHOR]

A band gap of ∼2.1 eV was obtained through the hybridization of reduced graphene oxide (rGO) with insulating hexagonal boron nitride (h-BN). The h-BN/rGO superlattice behaved like n type semiconductor due to the enriched electron density at the conduction band and allowed charge transfer depending on the redox potential of the electrolyte. The band gap energy was further minimized to ∼1.79 eV through fluorine (F) doping within the h-BN/rGO. F doping created population density near the valance band and the Fermi level shifted towards the lower energy level. F doped superlattice behaved like p type semiconductor where F was adsorbed mostly at the N site. It is noticed that the contribution of the redox charge transfer to the overall capacitance was increased in comparison to the electrochemical double layer capacitance with increasing F doping. The formation of defects and disorder due to doping provided facile diffusion path enhancing the charge storage contribution from the interior site of the electrode materials. The specific capacitance of the F doped h-BN/rGO superlattice was determined as 1250 F g −1 which is 130% of un-doped sample. An asymmetric supercapacitor (ASC) cell was fabricated with F doped h-BN/rGO superlattice, which showed almost zero IR drop, high stability (∼77% retention of capacitance after 10,000 charge–discharge cycles) and large energy and power density of 87.5 W h kg −1 and 6300 W kg −1 , respectively. Furthermore, the ASC also exhibited very low relaxation time constant of ∼0.39 ms ensuring effective power delivery and quick charge–discharge capacity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu 1 N 3 -linked Mo 1 S 2 adjacent diatomic entities decorated CN was prepared. • The adjacent diatomic metal Cu and Mo efficiently modulate electronic structure of CN. • The catalyst shows excellent photocatalysis with 85 times higher than bulk CN. • This is ascribed to the closer conduction band to the Fermi level and promoted charge transfer. • This work provides a new avenue for the design of diverse adjacent diatomic catalysts. The regulation of the electronic structure of graphitic carbon nitride (CN) has been considered as one of the most promising methods to improve its photocatalytic efficiency. However, how to adjust effectively the electronic structure remains a great challenge. Herein, we pioneered a microwave-assisted solvothermal sulphidation strategy for the preparation of Cu 1 N 3 -linked Mo 1 S 2 adjacent diatomic entities decorated CN (Cu 1 N 3 /Mo 1 S 2 /CN) through the enabled sulphidation around single Cu atom by the super hot spots owing to the localized surface plasmon resonance effect. The electronic structure of CN is regulated by the synergistic effect of the adjacent diatomic metal Cu and Mo, which not only makes the conduction band of the catalyst closer to the Fermi level, but also improves the charge transfer of CN. As a result, Under visible light irradiation and atmosphere conditions, the H 2 generation rate (HER) of the Cu 1 N 3 /Mo 1 S 2 /CN catalyst reaches as high as 6.14 mmol g-1h−1, which is 85 times higher than that onbulk CN. It was highlighted that the introduced Cu 1 N 3 -linked Mo 1 S 2 adjacent diatomic entities act as modulator to efficiently tune the electronic structure of the CN semiconductor, rather than as active sites, and for all samples, the deposited Pt is requested to act as active sites for H 2 production. This work not only provides enlightenment for the development of an outstanding non-precious metals modified CN-based photocatalyst for solar hydrogen production, but also provides a new avenue for the design of diverse adjacent diatomic catalysts towards various transformations. [ABSTRACT FROM AUTHOR]

[Display omitted] • N and O co-coordination of Fe single atom is realized by pre-oxidation strategy. • The coordination of axial O to Fe optimizes the adsorption energy of oxygen species. • This work reveals that Fe nanoparticles can induce more Fe single atoms to de-anchor. • SA-FeN 4 O 1 -C catalyst shows excellent performance in GDE half-cell and ZABs. Single-atom catalysts have recently emerged as a promising replacement for noble metal catalysts in the oxygen reduction reaction (ORR) on the cathode side of fuel cells and metal-air batteries. However, regulating the precise coordination environment of central atoms remains challenging. In particular, constructing co-coordination active site with N and O atom is rarely investigated. Here, an unreported pre-oxidation strategy is proposed to establish the Fe-O bond for the synthesis of the Fe-N 4 O 1 single-atom structure. The obtained SA-FeN 4 O 1 -C catalyst exhibits remarkable ORR performance, possessing a half-wave potential 30 mV higher than that of the commercial Pt/C and a kinetic current density 7.4 times that of Pt/C at 0.8 V (vs. RHE). More significantly, when employed as an air cathode, the overpotential is 340 mV lower than that of Pt/C when operating at a high current density of 350 mA cm−2 in a GDE half-cell, and a maximum power density of 205.8 mW cm−2 and a high energy density of 1024.9 w h kg−1 can be achieved in a zinc-air battery. According to the DFT, axial oxygen coordination can lower the energy barrier for ORR by driving the d-band center of the Fe atom to shift away from the Fermi level and generate a moderate oxygen adsorption energy. Importantly, the essence of the formation of the Fe-N 4 O 1 structure and single-atomic active sites was revealed. This work opens up an innovative strategy for constructing single-atom sites with axial oxygen coordination and provides valuable insight into the synthesis of atomically dispersed materials. [ABSTRACT FROM AUTHOR]

• A favorable preparation strategy toward FeP/Fe 2 P heterostructure is proposed by regulating the calcination temperature of phosphating process. • Deciphering the role of energy gap between cation 3d and anion 2p band in regulating the adsorption and catalysis of polysulfides. • The charge migration and an internal electric field of FeP and Fe 2 P are induced after reaching a thermodynamic equilibrium state. Exploring advanced electrocatalysts and understanding their mechanism in regulating polysulfides-transformation is of great importance but a challenging task for lithium-sulfur batteries (LSBs). Herein, FeP/Fe 2 P heterostructure nanoparticles with an internal electric field, prepared by a temperature-controlled phosphating process, can effectively improve the electrocatalytic activities of the bidirectional Li 2 S deposition/dissolution. This improvement can be attributed to the modulating absorptivity of lithium polysulfides (LiPSs) and propelling charge transfer. The reduced d-p band center between bonding and antibonding orbitals of the Fe 3d and P 2p band in the heterostructure enables bonding with LiPSs to achieve a higher electronic concentration at the Fermi level. This regulates the adsorption-diffusion-conversion process, reduces the activation energy, and improves the Li+ diffusion. Benefiting from the boosted kinetics of the FeP/Fe 2 P heterostructure, the cells exhibit a high reversible capacity of 1412 mAh g−1 at 0.1 C and outstanding energy efficiency of ∼ 90% from 0.1 C to 2 C. Furthermore, the cell with high sulfur loading of 4 mg cm−2 demonstrates a high capacity of 786 mAh g−1 after 100 cycles at 0.5 C. This work presents an effective method and favorable guidance for developing advanced heterostructures in LSBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnO-Mo 2 C heterogeneous particles supported on porous carbon are designed using chitosan. • MnO-Mo 2 C/C accelerate the catalytic conversion of polysulfides and improve sulfur utilization. • The in situ XRD and Raman reveals mixed mechanisms of polysulfide conversion on MnO-Mo 2 C/C. • The MnO-Mo 2 C/C delivers a high specific capacity and long-cycle stability in Li–S batteries. • The MnO-Mo 2 C/C@S cathodes exhibit excellent electrochemical performances at a high loading. Poor conversion between sulfur and sulfur-related species and the dissolution of intermediates result in slow commercialization development. Herein, MnO-Mo 2 C heterogeneous particles supported on porous carbon (MnO-Mo 2 C/C) are synthesized using chitosan as a sulfur host for Li–S batteries. MnO-Mo 2 C heterogeneous particles possess superior calculated binding energies for sulfur redox and Fermi energy levels compared with single MnO and Mo 2 C, which suggests that MnO-Mo 2 C leads to a fast conversion of polysulfides and accelerates electron transport. In addition, in situ X-ray diffraction and Raman spectra measurements reveal mixed mechanisms of polysulfide conversion on MnO-Mo 2 C/C, wherein Li 2 S 6 undergoes LiS 3 and Li 2 S 4 reduction reaction paths. The MnO-Mo 2 C/C@S cathode exhibits a high discharge specific capacity (929.6 mAh/g) and ultra-low decay rate of 0.019 % at 2C for 1200 cycles. Even at a sulfur loading of 8.0 mg cm−2, the MnO-Mo 2 C/C@S cathode exhibits a high reversible area capacity of 5.10 mAh cm−2. [ABSTRACT FROM AUTHOR]

The electron mediator plays an important role in charge transfer in an artificial all-solid-state Z-scheme system. According to the energy band theory, a visible light photocatalytic system was designed by using reduced graphene oxide (RGO) as the electron mediator. The as-prepared g -C 3 N 4 /RGO/Bi 2 MoO 6 composite was synthesized by hydrothermal process, and it was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen sorption, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS) and diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the g -C 3 N 4 /RGO/Bi 2 MoO 6 composite was evaluated by analyzing the degradation of Rhodamine B (Rh B) under visible light irradiation. The photocatalytic degradation rate of Rh B for the g -C 3 N 4 /RGO/Bi 2 MoO 6 composite was 8.73 and 5.19 times for the Bi 2 MoO 6 and g -C 3 N 4 /Bi 2 MoO 6 composite, respectively. The matched Fermi level structure provided the favorable interfacial charge transfer from the Bi 2 MoO 6 Photosystem II (PS II) to the g -C 3 N 4 Photosystem I (PS I) to promote the photocatalytic degradation of Rh B, suggesting that RGO was a suitable electron mediator in the Z-scheme system. The present study can provide a scientific basis for the rational design and realization of the Z-scheme system in environmental application. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoS 2 (30)/NaNbO 3 piezocatalytic heterojunction achieved 82.8% metronidazole removal. • COMSOL simulations revealed the role of NaNbO 3 as parallel plate capacitor. • NaNbO 3 provided internal bias to MoS 2 which formed electrocatalytic system. • Piezopotential improved redox potential of holes at MoS 2 -water and MoS 2 -NaNbO 3 interface. • Electrocatalytic formation of H 2 O 2 at MoS 2 cathode and oxidation at MoS 2 anode produced.OH. Piezocatalytic heterojunction was synthesized using sodium niobate (NaNbO 3 , NBO) and molybdenum disulfide sheets (MoS 2 , MS), and characterized via SEM, XRD, XPS, UPS, EPR, PFM, and EIS. Metronidazole (MET) removal using MS(x)/NBO heterojunction was tested via batch experiments in an ultrasonicator (40 kHz and 150 W) for 160 min. MET removal obtained under optimized MS(30)/NBO (30 wt% of MS) was 82.8%, and the removal mechanism was governed by .OH formed due to reduction of H 2 O 2 , electrocatalytic oxidation at MS anode, and oxidation by holes in depletion region at MS-water and MS-NBO interface. Scavenging and quantification studies confirmed the formation of H 2 O 2 (∼27 µM) due to piezoelectric effect induced electrocatalysis. In the absence of piezoelectric effect, MET removal and .OH formation were insignificant. Moreover, COMSOL simulation revealed the role of orthorhombic NBO as parallel plate capacitor in the heterojunction that created electrocatalysis and formation of depletion and accumulation regions at MS-NBO and MS-water interface. Finally, effects of pH (2–12), competitive anions (Cl−, NO 3 –, SO 4 2−, CO 3 2–, and PO 4 3−) and working temperature (28–63 ℃) on piezocatalytic MET removal were investigated through experiments and theoretical understanding. The increase in temperature due to ultrasonication improved efficiency of MET removal due to improvement in interfacial charge transfer, and increase in thermodynamic feasibility of .OH generation. Overall, MS(30)/NBO activity could be attributed to generation of charge carriers due to mechanical excitation and formation of piezoelectric effect due to cavitation under ultrasonic waves. [ABSTRACT FROM AUTHOR]

[Display omitted] • {1 2 ¯ 3} faceted NiWO 4 -Ni 3 S 2 @NiO/NF electrodes with tunable S vacancies were devised. • The facets and S vacancies on Ni 3 S 2 determined the overpotential (η) and TOF in HER. • A η 10 of 89 mV and a TOF of 1.5 × 10−3 s−1 were attained on NiWO 4 -Ni 3 S 2 @NiO/NF-3. • DFT calculations revealed the manipulation mechanism of facets and S vacancies. • An overall-water-splitting current density of 10 mA cm−2 at 1.64 V was achieved. Designing nonprecious electrocatalysts with outstanding performances in hydrogen evolution reaction (HER) via water splitting is attractive for renewable energy conversion. Here, a free-standing and binder-free electrode by in-situ growing a multi-level layered electrocatalyst consisted of NiWO 4 -coupled Ni 3 S 2 nanofibers with secondary NiO layer on Ni foam (NiWO 4 -Ni 3 S 2 @NiO/NF) is devised, in which NiWO 4 was recognized to boost the exposure of high-index {1 2 ¯ 3} facets on Ni 3 S 2 and NiO was identified to increase the electron density of Ni 3 S 2 via accumulating S vacancies. Such an integration of high‑index‑facet exposure and electron-density optimization endowed the resultant NiWO 4 -Ni 3 S 2 @NiO/NF-3 (3 represents the nominal Ni: S molar ratio in fabricating Ni 3 S 2) electrode with a more suitable H adsorption energy on the active Ni sites and a positive shift of the d-band center of Ni 3 S 2 toward the Fermi level, resulting in a strengthened Ni–H interaction. As a consequence, a low overpotential of 89 mV to deliver a current density of 10 mA cm−2 and a high turnover frequency of H 2 generation of 1.5 × 10−3 s−1 for HER in 1 mol l−1 KOH were acquired on NiWO 4 -Ni 3 S 2 @NiO/NF-3, both outperforming the Ni 3 S 2 /NF-1, NiWO 4 -Ni 3 S 2 /NF-1, and NiWO 4 -Ni 3 S 2 @NiO/NF-1 electrocatalysts. Remarkably, an electrolytic cell assembled by using NiWO 4 -Ni 3 S 2 @NiO/NF-3 as both anode and cathode delivered an overall-water-splitting current density of 10 mA cm−2 at 1.64 V, evidencing its robust bifunctional catalytic ability in water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Fe3Se4/FeSe@MXene is synthesized by in situ growth and selenization. • The built-in electric field is established at the interface of the heterojunction. • Fe3Se4/FeSe@MXene is responsible for the capture-adsorption-catalytic of LiPS. • In situ Raman demonstrated that the catalyst inhibited the shuttle effect. Developing advanced catalysts with high chemisorption toward promoting the conversion of lithium polysulfide (LiPS) is the key to the commercial application of Lithium-sulfur (Li-S) batteries. Here, a novel catalyst consisting of Fe 3 Se 4 /FeSe heterojunctions encapsulated in two-dimensional (2D) MXene nanosheets is prepared by in situ growth and selenization of Fe-MOFs. The MXene skeleton captures polysulfides effectively and the Fe 3 Se 4 /FeSe heterojunction plays a catalytic role as well as their strong synergistic effect achieves "capture-adsorption-catalysis" of LiPS. A Li-S battery with Fe 3 Se 4 /FeSe@MXene-PP separator delivers a high specific capacity (1104.2 mAh/g at 0.2C) and outstanding rate capacity (758.8 mA h g−1 at 4C). Even with sulfur loading as high as 5.8 mg cm−2, the Li-S battery has a high specific capacity of 862.6 mAh/g at 0.2C and cycle stability (92.3 % retention after 120 cycles). The involved mechanisms of performance improvement were discussed and demonstrated by density function theory (DFT) calculations and in situ Raman analysis. Interface engineering of the Fe 3 Se 4 /FeSe increases the density of states at the Fermi level, reduces the activation energy of Li 2 S decomposition, and the establishment of an internal electric field accelerates charge transfer. This work provides an effective approach to the design of high-performance catalysts for improved Li-S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Inhibit undesirable iodide-rich perovskite intermediate phases by LiAc doping. • Tune the Fermi level of CsPbI 2 Br to enhance interfacial charge extraction. • Passivate uncoordinated Pb2+ defects to reduce trap density. • A remarkable PCE of 16.05% is achieved in LiAc-doped CsPbI 2 Br PSCs. Additive engineering is an efficient approach to improve the photovoltaic performance of all-inorganic CsPbI 2 Br perovskite. However, rare attention has been paid to the CsBr intermediate, which has a significant effect on the perovskite crystallization process and thus the quality of final perovskite films. Herein, we find that the intermediate CsBr is formed during spin-coating of the CsPbI 2 Br precursor solution, which leads to the generation of iodide-rich perovskite (CsPbI 2+ x Br 1- x) phases in the precursor film. This finally results in low-quality perovskite film after thermal annealing. To suppress the CsBr formation, lithium acetate (LiAc) was added into the CsPbI 2 Br precursor solution. We find that the intermediate CsBr is significantly suppressed after doping of LiAc, which results in less phase segregations in the precursor film and thus high-quality CsPbI 2 Br film after thermal annealing. The LiAc-doped perovskite film shows higher crystallinity, larger grain size and more preferential orientation than the pristine perovskite film. Furthermore, Ac‾ coordinates with Pb2+ to passivate uncoordinated Pb2+ defects, and Li+ aggregates at the perovskite surface to upwardly shift the Fermi level of CsPbI 2 Br closer to the conduction band edge, which leads to the suppressed trap-assisted recombination losses and the enhanced interfacial charge extraction in the LiAc-doped perovskite solar cells (PSCs). As a result, a remarkable power conversion efficiency (PCE) of 16.05% is achieved in LiAc-doped CsPbI 2 Br PSCs. Moreover, the devices exhibit superior thermal stability with almost no PCE degradation after 300 h of thermal aging at 85 °C. Our results provide deep insights into the doping effect of additive, especially on perovskite crystallization kinetics, which are important for the future optimization of high-performance all-inorganic PSCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The tunnel-type Ti-substituted Na 0.44 MnO 2 was investigated as cathode for aqueous zinc batteries. • The Ti-substitution can efficiently improve the electrochemical kinetics with superior high-rate capability and cycling stability. • The facilitated reaction mechanism with stepwise Zn2+ and H+ insertions was versified. • The optimal Na 0.44 Mn 0.78 Ti 0.22 O 2 material exhibits a high reversible capacity and a cycling life record for 2400 cycles. The tunnel-type sodium manganese oxide (Na 0.44 MnO 2) materials are considered as promising cathode candidates for rechargeable batteries due to their low cost and sustainability. However, the direct implementation in aqueous batteries, as an emerging energy storage technology, was not fully realized in terms of the reversibility and long-cycling stability. Herein, the tunnel-type Ti-substituted Na 0.44 MnO 2 (NMTO) is investigated as a cathode material for aqueous zinc-metal batteries. It is identified that the Ti-substitution has a significant effect on improving its rate capability and cycling stability. As a result, the optimal Na 0.44 Mn 0.78 Ti 0.22 O 2 (NMTO-0.22) material exhibits a reversible capacity of 109.6 mAh/g at 1.0 A g−1, and 71% of the initial capacity can be retained after 2400 cycles. Such performance can be attributed to the enhanced insertion mechanisms in the tunnel structure, as verified by the post-mortem spectroscopic and microscopic techniques. Density functional theory (DFT) calculations enclose that the average charge density in Mn 3d orbits near the Fermi level and Mn participation in redox reaction are improved after Ti-substitution, supporting the facilitated electrochemical kinetics of NMTO. This work demonstrates that the Ti-substituted Na 0.44 MnO 2 is a promising cathode material for aqueous zinc-metal batteries, and provides a fundamental understanding on the charge storage mechanisms. [ABSTRACT FROM AUTHOR]

• K+ and CeO 2 promote photocatalytic toluene oxidation of CeO 2 /K-OMS-2 (Ce/KM). • K+ changing the Fermi level generates Z-scheme heterojunction and promotes Mn3+ for generating OH and absorbing toluene. • More active radicals, oxygen species, Ce3+/4+ and absorption of O 2 lead to better stability of Ce/KM. • Benzyl alcohol intermediates deposit and poison only K-OMS-2, not Ce/KM. For photocatalytic toluene oxidation, available photo-generated charges and active oxygen species are of great importance. Due to the advantages of K+ and CeO 2 , CeO 2 /K-OMS-2 (Ce/KM) were prepared for photocatalytic toluene oxidation, which exhibited better activity and stability than that of Ce/0M (no K+) and K-OMS-2. The band structures and DFT calculations revealed that K+ in the K-OMS-2 tunnels changing Fermi levels led to Z-scheme heterojunction formation, and acting as charge modulation kinetically promoted photo-charge transfer. Meanwhile, the charge balance of K+ increased the proportion of Mn3+, leading to the generation of hydroxyl groups for toluene adsorption via strong OH-π interactions. In addition, oxygen adsorbed on Ce3+ and □-Ce3+-O-Ce4+, and enhanced oxygen migration were observed on Ce/KM, which further interacted with photo-generated charges to generate radicals. In situ DRIFTS and GC–MS suggested the degradation pathway, i.e. , the oxidizing radicals on Ce/KM attacked methyl of toluene, formed benzaldehyde, benzoic acid intermediates, opened benzene ring and finally mineralized into carbon dioxide and water. Notably, benzyl alcohol intermediate deposited and poisoned only K-OMS-2, not Ce/KM, confirming the excellent stability of Ce/KM. Furthermore, the effects of the humidity on reaction process were revealed. [ABSTRACT FROM AUTHOR]

• A self-powered PEC sensor was designed by constructing stepped energy band structure. • The mechanism of electrons transfer driven by the Fermi level gap was proved by DFT. • The self-powered sensor exhibited superior performances for the detection of CQP. Fabricating a self-powered photoelectrochemical (PEC) sensor with superior performances and cost-effective design is highly desirable but still remains challenges. Herein, we develop a self-powered PEC molecular imprinted (MIP) sensor integrating WO 3 /TiO 2 photoanode and gold nanoparticles modified carbon intercalated MoS 2 photocathode for highly sensitive and specific detection of chloroquine phosphate (CQP). By constructing a reasonable stepped energy band structure, the electrons are efficiently transferred driven by the Fermi energy level gap between photoanode and photocathode, which amplifies the cathodic photocurrent. Furthermore, the mechanism of electron transfer driven by the Fermi energy level gap in the self-powered sensor was demonstrated for the first time by density functional theory (DFT). The Molecular imprinted polymer was modified on the photocathode as recognition element, which avoids the interference of reducing substances in the samples and complex biometric reactions. Under optimal conditions, the proposed MIP sensor for CQP presents the detection limit of 0.11 μM with a broad linear range from 10−6 M to 10−3 M. This work presented an innovative design strategy for constructing self-powered sensor. [ABSTRACT FROM AUTHOR]

[Display omitted] • Energy density of 19.3 J cm−3 and efficiency of 61 % are achieved at 549.2 kV mm−1. • Lamellar-structured BiFeO 3 @TiO 2 fillers possess BFO/TO/BFO triple-layered structure. • Breakdown strength is significantly enhanced by BiFeO 3 @TiO 2 fillers. • Opposite double heterojunction electric field forms between BiFeO 3 and TiO 2 layers. • Opposite double heterojunction electric field offsets most applied electric field. Polymer-based dielectric capacitors are well recognized for high energy density and efficiency. However, the energy density is restricted by the deterioration of breakdown strength with excessive addition of inorganic fillers. Herein, an innovative design of the lamellar-structured BiFeO 3 @TiO 2 (BFO@TO) fillers is proposed and a small amount of BFO@TO is added into P(VDF-HFP)/PMMA blended polymer to fabricate BFO@TO-P(VDF-HFP)/PMMA composites, which delivers an outstanding energy density of 19.3 J cm−3 at 549.2 kV mm−1. The filler possesses a BFO/TO/BFO triple-layered structure. Due to the different Fermi level, electrons are injected from TO into BFO to form electron accumulation layer and construct the heterojunction electric fields between TO and BFO layers. Heterojunction electric fields at two interfaces produced by the triple-layered structure are opposite. The opposite double heterojunction can withstand larger external electric field and improve the breakdown strength. Besides, BFO, as a narrow bandgap semiconductor, is easier for electrons and holes to separate, which further widens the width of the built-in electric field and reduces the dielectric breakdown. Electric field distribution simulations intuitively confirm the enhancement of the breakdown strength. The results provide an effective strategy to address the critical issue of improving the breakdown strength for high energy storage capability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel BiVO 4 /BiOBr-Ov Z-scheme heterojunction has been prepared. • The existence of oxygen vacancies leads to altering the photogenerated carrier transfer path from type-II to Z-scheme. • The internal electric field and band edge bending are explained based on the results of DFT calculations. • The mechanism of Z-scheme photocatalysis is discussed. • •O 2 − and h+ were the prominent radicals for OTC degradation. Constructing oxygen vacancies (Ov) has been widely used to enhance photocatalytic activity as a conventional and efficient approach, but its influence on the interfacial charge transfer pathway remains ambiguous. Herein, we synthesized BiVO 4 /BiOBr-Ov (BVB-Ov) photocatalysts through a facile method. Subsequently, various characterization results verified the successful preparation of BVB-Ov composites via combining BiVO 4 with BiOBr containing oxygen vacancies (BiOBr-Ov). The results of photocatalytic degradation experiments illustrated that 20% BVB-Ov exhibited the highest degradation rate (91%) for Oxytetracycline (OTC), which was much higher than that of 20% BiVO 4 /BiOBr (71%). In addition, three possible degradation pathways were deduced from liquid chromatography-mass spectrometry (LC-MS) analysis. Photoelectrochemical, photoluminescence (PL) and time-resolved PL (TRPL) investigation revealed that 20% BVB-Ov possessed the fastest photogenerated carrier separation and transportation rate. Kelvin probe force microscopy (KPFM) technology and Density functional theory (DFT) calculations have shown that the introduction of oxygen vacancies modulated the relative positions of the Fermi levels between BiVO 4 and BiOBr. We have finally combined DFT calculations, energy band analysis, trapping experiments and electron paramagnetic resonance (EPR) results, confirming that the existence of oxygen vacancies led to altering the photogenerated carrier transfer path from type-II to Z-scheme. This work provided insights and guidelines for oxygen vacancies to coordinate interfacial charge transfer pathways. [ABSTRACT FROM AUTHOR]

Ti 3 C 2 T x MXene was doped into Cs 2 AgBiBr 6 perovskite layer based on D149 indoline dye-sensitized TiO 2 to enhance its crystallinity, absorption intensity and carrier mobility, leading to high power conversion efficiencies of 4.47 % under 1 sun illumination and 7.23 % under 200 lx indoor light illumination with better stability for Cs 2 AgBiBr 6 double perovskite solar cells. [Display omitted] • Ti 3 C 2 T x enhances the crystallization of Cs 2 AgBiBr 6 and offers better mobility. • Ti 3 C 2 T x can adjust the valence band of Cs 2 AgBiBr 6 through the Fermi level. • High PCE of 4.47% under 1 sun illumination with enhanced stability was achieved. • High PCE of 7.23 % under 200 lx indoor light illumination was achieved. Cs 2 AgBiBr 6 is considered an emerging candidate for lead-free inorganic double perovskite solar cells (PSCs). However, the photovoltaic performance of Cs 2 AgBiBr 6 is restricted while the reported power conversion efficiencies (PCEs) are almost lower than 3%. Here, we employed D149 indoline dye to sensitize the TiO 2 electron transport layer (ETL) and introduced Ti 3 C 2 T x MXene nanosheets into Cs 2 AgBiBr 6 to enhance its crystallization. Both Cs 2 AgBiBr 6 and D149 indoline dye could contribute to the photocurrent. Moreover, the calculations of the interface properties and electron structure were carried out based on density functional theory. Weak van der Waals forces between the interfaces of Cs 2 AgBiBr 6 and Ti 3 C 2 T x allow the perovskite to retain its semiconductor properties, while effectively weaken the Fermi level pinning (FLP). The high work function of Ti 3 C 2 T x adjusts the valence band of Cs 2 AgBiBr 6 through the Fermi level to improve carrier mobility. As a result, PCEs of 4.47 % under 1 sun illumination and 7.23 % under 200 lx indoor light illumination with enhanced long-term stability were achieved. Hence, this work demonstrates the great potential of Ti 3 C 2 T x for double PSCs and predicts other MXenes with higher work function for further applications. [ABSTRACT FROM AUTHOR]