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This study uses first-principles calculations to investigate the asymmetric Zr2CO/VSe2 heterostructure for hydrogen evolution reaction (HER) applications, focusing on its interlayer interactions, electronic structures, and HER performance across six stacking angles. Our findings demonstrate remarkable structural stability, characterized by interlayer distances of 2.1 Å to 2.7 Å and binding energies from −150.521 to −257.939 meV Å−2. Band structure analyses highlight the heterostructures' exceptional conductivity, essential for catalytic efficiency. Additionally, charge density difference calculations reveal significant charge transfer and redistribution at the interface, providing insights into the interlayer interactions and their influence on catalytic activity. Notably, the Gibbs free energy of hydrogen adsorption (ΔGH*) remains within ±0.1 eV across all configurations, indicating superior HER activity. Further analysis shows that the work function (Φ) serves as a critical electronic structure descriptor, influencing HER performance. The relationship between work function and ΔGH* across different interlayer distances underscores the predictive value of the work function for HER activity. These insights provide a theoretical foundation for developing advanced and effective non-noble metal HER catalysts, paving the way for innovations in sustainable energy technologies. [ABSTRACT FROM AUTHOR]

This investigation highlights the significant impact of asymmetric Janus Zr2COT (T = F, Cl, Br, I) monolayers on enhancing the hydrogen evolution reaction (HER) performance. Employing density functional theory (DFT), our research demonstrates that introducing asymmetric functional groups into Zr2COT structures effectively tailors their electronic properties, leading to a marked improvement in HER activity. This structural innovation notably reduces the hydrogen adsorption Gibbs free energy (ΔGH*) from 0.877 eV for the symmetric Zr2CO2 to below 0.2 eV for the Janus Zr2COT configurations, with Zr2COBr and Zr2COI achieving exceptionally low ΔGH* values of 0.045 and −0.042 eV, respectively, at a hydrogen coverage of 1/4. The monolayers also exhibit remarkable thermal stability and superior electrical conductivity, vital for high-efficiency electrocatalysis. Furthermore, strain engineering underscores the durability of these materials, maintaining ΔGH* values within ±0.2 eV under extensive tensile strain and emphasizing their practical application potential. Crucially, this work uncovers the critical role of electronic structure adjustments in optimizing the HER performance, aligning with the Sabatier principle, and offering fresh perspectives for designing effective, cost-efficient electrocatalysts. In a word, Janus Zr2COT monolayers emerge as promising candidates, challenging traditional noble metal catalysts and paving the way for the development of sustainable electrocatalytic materials. [ABSTRACT FROM AUTHOR]

The corrosion, parasitic reactions, and aggravated dendrite growth severely restrict development of aqueous Zn metal batteries. Here, we report a novel strategy to break the hydrogen bond network between water molecules and construct the Zn(TFSI)2‐sulfolane‐H2O deep eutectic solvents. This strategy cuts off the transfer of protons/hydroxides and inhibits the activity of H2O, as reflected in a much lower freezing point (<−80 °C), a significantly larger electrochemical stable window (>3 V), and suppressed evaporative water from electrolytes. Stable Zn plating/stripping for over 9600 h was obtained. Based on experimental characterizations and theoretical simulations, it has been proved that sulfolane can effectively regulate solvation shell and simultaneously build the multifunctional Zn‐electrolyte interface. Moreover, the multi‐layer homemade modular cell and 1.32 Ah pouch cell further confirm its prospect for practical application. [ABSTRACT FROM AUTHOR]

Zn metal at a low cost, high theoretical capacity, and no harm to the environment is considered as the most promising anode for aqueous batteries. However, in the slightly acidic electrolytes, hydrogen evolution and spontaneous Zn corrosion damage the service life of Zn-based batteries and further seriously restrict their large-scale application in energy storage fields. Herein, we first study the corrosion mechanism of Zn in ZnSO4 solution with tetramethylammonium sulfate (TS) additive and report a method for the co-modification of the Zn anode with ZnO@Cu solid solution interface and TS additive. The obtained ZnO@Cu artificial layer and TS additive can not only inhibit Zn corrosion and induce Zn electroplating/peeling on the Zn surface, but also promote uniform deposition of Zn in the battery charge/discharge process. Density functional theory (DFT) calculations and in situ optical microscopy observations reveal the strong zincophilic properties of the ZnO@Cu artificial layer and the distinctive zincophobic mechanism of TS. As a result, this dendrite-free Zn electrode displays low polarization (22.3 mV at 0.25 mA cm−2) and high cycling stability (over 4500 h at 0.25 mA cm−2), which was also confirmed in an NH4V3O8‖ZnO@Cu/Zn-TS full-cell with a capacity retention of 84% after 1500 cycles. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous Zn‐ion batteries (ZIBs) are always regarded as a promising energy storage device owing to their higher safety and durability. However, two problems have become the main trouble for the practical application of ZIBs such as the dendrite growth of Zn metal anode in electrolyte and the freezing of water solvent at low temperature. Herein, to overcome these challenges, a new strategy, multi‐component crosslinked hydrogel electrolyte, is proposed to inhibit Zn dendrites and realize low temperature environmental adaptability for ZIBs. Benefitting from the superior inhibition effect of the polyacrylamide and dimethyl sulfoxide (DMSO) on Zn dendrites, the coulombic efficiency of the symmetric cell of ≈99.5% is achieved during the Zn plating/stripping over 1 300 h, and the assembled full‐cell demonstrates the large specific capacity of 265.2 mAh g‐1 and high cyclic stability with the capacity retention of 95.27% after 3 000 cycles. In addition, the full‐cell delivers stable operation at a wide temperature range, from 60 to −40 °C, due to the introduction of additive DMSO. This work provides an inspired strategy and novel opportunities to realize a dendrite‐free and wide‐temperature rechargeable aqueous Zn‐ion energy storage system. [ABSTRACT FROM AUTHOR]

Improving the sensitivity of MoS2-based photodetectors by constructing semiconductor heterostructures remains a challenge. To address this issue, the effects of interlayer spacing and vertical external electric fields on the interfacial interactions and electronic properties of Zr2CO2/MoS2 heterostructures were investigated systematically by first-principles calculations. The results indicate that a stable interface with van der Waals interactions can form between Zr2CO2 and MoS2, which complies with the type-II mechanism. By applying a vertical external electric field to the Zr2CO2/MoS2 heterostructure or changing the interlayer spacing between the Zr2CO2 and MoS2 monolayers, both the band gap and heterostructure type at the Zr2CO2/MoS2 interface can be modulated efficiently. It is remarkable that the band alignment of the Zr2CO2/MoS2 heterostructure is more sensitive to the external electric field than to the interlayer spacing. When the electric field is from −0.5 to 0.5 V Å−1, the energy band of the Zr2CO2/MoS2 heterostructure changes from 0.2 to 0.3 eV with a 0.1 V Å−1 increase of electric field. The redistribution of charge density with the external electric field and interlayer coupling is revealed to account for the tunable energy bands. Therefore, the Zr2CO2/MoS2 heterostructures with van der Waals interactions possess great potential to be used in high-performance photodetectors. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc ion batteries have attracted increasing attention as a new energy storage system because of the high ionic conductivity and safe aqueous electrolyte. The spontaneous vanadium dissolution in aqueous electrolytes is one major problem because the water with serious polarity would corrode the crystal structure of vanadium‐based cathodes. Here, an in situ artificial cathode electrolyte interphase (CEI) strategy is proposed to kinetically suppress the vanadium dissolution in aqueous zinc ion batteries. The strontium ion is introduced into vanadium oxide layers as a sacrifice guest, which would directly precipitate upon getting out from the vanadium‐based cathode to in situ from a CEI coating layer on the surface. This strategy is proven with the help of various technologies, and the remarkable ability of the CEI layer to suppress cathode dissolution is evaluated by multiple electrochemical and chemical methods. As a result, the cathode after CEI conversion exhibits the best recharge capacity retention after open circuit voltage rest for 3 days in comparison with other cathodes. This work reports a general strategy to construct the electrode‐electrolyte interface for suppressing vanadium‐based cathodes dissolution in aqueous electrolytes and beyond. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc ion batteries (AZIBs) have attracted increasing attention because of high ionic conductivity and non-flammable electrolytes. The spontaneous reaction of vanadium dissolution in aqueous electrolytes is a major problem for vanadium-based cathodes, since the water molecules with strong polarity could easily attack the vanadium-based cathodes crystal structure and directly lead to capacity deterioration. Here, a strategy of guest engineering is used to regulate the interlayer binding energy between vanadium oxide layers, thus thermodynamically suppressing vanadium dissolution. First-principles calculations indicate that a large interlayer binding energy of up to 208.1 meV Å−2 between vanadium oxide layers is obtained with NH4+ and H2O co-intercalation, which is more than tenfold that of V2O5. The as-prepared compound (NH4)2V6O16·1.5H2O (NH–V) restrains the vanadium dissolution effectively as expected. The electrolyte with NH–V immersion remains colorless even after 200 days, and the vanadium concentration of this electrolyte is thirty-seven times less than that of V2O5. Moreover, benefiting from this ultra-good chemical stability, the NH–V cathode shows an impressive recharge capacity retention of 98.5% after the open circuit voltage test for three days, which is 23% higher than that of V2O5. These results demonstrate that the guest engineering strategy could be a feasible way to construct robust layer structures, suppress the cathode dissolution, restrain self-discharge and improve the battery storage time. This work can provide new insights to understand the cathode dissolution behavior and it will be helpful to develop cathode materials with robust structures for suppressing cathode dissolution in aqueous batteries and beyond. [ABSTRACT FROM AUTHOR]

An understanding of the high photocatalytic performance reported for MoS2/BiOI nanocomposite is far from satisfactory. Here, the interfacial interaction and electronic properties of a MoS2/BiOI heterostructure were investigated systematically for the first time by first-principle calculations incorporating a semi-empirical dispersion-correction scheme. Our results confirm the reasonable existence of van der Waals interactions and a favorable Z-scheme mechanism, based on the typical interfacial cohesive energy and the energy level lineup at the interface. Analyzing the charge density differences and work functions, the built-in electric field is formed along the direction from MoS2 to BiOI after the interface equilibrium, and facilitates the separation of photoinduced electron–hole pairs in the interface. Additionally, it can be inferred that the incorporation of MoS2 into BiOI increases the carrier mobility and improves light harvesting, in agreement with the previously reported experimental data. Our work provides an insight into the mechanism of the enhanced visible-light photocatalytic activity of a MoS2/BiOI heterostructure, and helps to design other new heterostructure combinations. [ABSTRACT FROM AUTHOR]

Two dimensional (2D) heterojunction based on g‐C3N4 and CuInS2(CIS) nanosheets has been successfully constructed with the assistance of biomolecules L‐cysteine. We demonstrated that a typical p–n junction charges transfer mode of CIS/PCN (protonated g‐C3N4) can be switched to Z‐scheme transfer mode through the integration of Au by weakening the role of built‐in electric field. The morphology of CIS/Au/PCN can be well adjusted through the formation of Au−S covalent bond and the electrostatic adsorption between Au and PCN during the hydrothermal process. Furthermore, the intimate interface contact inside CIS/Au/PCN heterojunction was indeed constructed, which may promote the charges separation and transfer process at the interface as evidenced by ESR spectra and time‐resolved PL spectra. Under visible light illumination, the CIS/Au/PCN exhibited an enhanced CO (19.46 μmol/g) and CH4 (1.18 μmol/g) yield in CO2 reduction, which was about 5.04 times and 2.03 times higher than pure PCN. The composite heterojunction also showed excellent photocatalytic activity for tetracycline degradation with a 87 % degradation efficiency in 1 hour, which was 2.07 times higher than pure PCN. The experimental and theoretical calculation results demonstrated that an all‐solid‐state Z‐scheme heterojunction was formed in the CIS/Au/PCN system, which was different from the typical p–n junction charges transfer mechanism in CIS/PCN. [ABSTRACT FROM AUTHOR]

Maximizing the activity of materials towards the alkaline hydrogen evolution reaction while maintaining their structural stability under realistic working conditions remains an area of active research. Herein, we report the first controllable surface modification of graphene(G)/V8C7 heterostructures by nitrogen. Because the introduced N atoms couple electronically with V atoms, the V sites can reduce the energy barrier for water adsorption and dissociation. Investigation of the multi‐regional synergistic catalysis on N‐modified G/V8C7 by experimental observations and density‐functional‐theory calculations reveals that the increase of electron density on the epitaxial graphene enable it to become favorable for H* adsorption and the subsequent reaction with another H2O molecule. This work extends the range of surface‐engineering approaches to optimize the intrinsic properties of materials and could be generalized to the surface modification of other transition‐metal carbides. [ABSTRACT FROM AUTHOR]

The surface properties of BiPO4 exert a significant effect on the photocatalytic performance under ultraviolet irradiation, but they have not been well explored, either experimentally or theoretically. Herein, for the first time, we systematically studied the structures and energetics of four low-index stoichiometric surfaces of monazite BiPO4 using density functional theory. A new scheme is proposed to correct the surface energy and compare this with the average surface energy. Both of the two schemes for the surface energies indicate that the order of the surface energies is (100) < (010) < (011) < (001), which is not completely consistent with their surface dangling bond densities. The main reason is incomplete PO4 tetrahedrons, namely, the existence of dangling P–O bonds in the bare (001) plane. However, only dangling Bi–O bonds are found in the other three low-index surfaces. It is obvious that the dangling bond density of the Bi atoms and the intact PO4 tetrahedrons are two crucial factors in the surface stability. Correspondingly, the differences in the planar-averaged electron density and the work function are presented to describe the charge distribution close to the surface. Furthermore, the equilibrium morphology calculated using the Wulff construction suggests that the (001), (010), (011) and (100) facets account for 15%, 33%, 16% and 36%, respectively. The two low-energy (100) and (010) facets dominate in the Wulff shape and make up almost 69% of the total crystal shape area. This work will provide theoretical guidance for the further design of effective BiPO4-based photocatalysts. [ABSTRACT FROM AUTHOR]

Controlling the p-type electrical transport behavior of nanoelectronic devices remains a grand challenge in reducing the Schottky barrier. To address this issue, we systematically investigate the effect of asymmetric Se doping on the interlayer interaction and electronic properties of a MoS2(1−x)Se2x/graphene heterostructure by first-principles calculations incorporating a semiempirical dispersion–correction scheme. The results show that the interfacial binding can be enhanced by Se doping inside the interface, while the effect of Se doping outside the interface is negligible on the interfacial binding. The type and height of the Schottky barrier can be tuned by changing the concentration and sites of the Se dopant at the interface. Further, it is found that by increasing the concentration of the Se dopant inside the interface the transition from an n-type Schottky barrier to a p-type can be realized, and a low p-type Schottky barrier is gained at the interface for highly efficient charge transfer. Lastly, it is confirmed that the redistribution of the interfacial charge leads to a shift of the Fermi level, and thus determines the type and height of the Schottky barrier. These conclusions provide rational evidence for the asymmetric doping concepts to design and fabricate MoS2-based field effect transistors. [ABSTRACT FROM AUTHOR]

Interfacial interactions and electronic properties of graphene/CH 3 NH 3 PbI 3 heterojunctions were investigated by first-principles calculations incorporating semiempirical dispersion-correction scheme to describe van der Waals interactions. Two lattice match configurations between graphene and CH 3 NH 3 PbI 3 (0 0 1) slab were constructed in parallel contact and both of them were verified to form remarkable van der Waals heterojunctions with similar work functions. Our calculated energy band structures show that the Dirac-cone of graphene and the direct band gap of CH 3 NH 3 PbI 3 are still preserved in the heterojunctions, thus graphene can be a promising candidate either as a capping or supporting layer for encapsulating CH 3 NH 3 PbI 3 layer. It is identified that the Schottky barrier of graphene/CH 3 NH 3 PbI 3 heterojunctions can be controlled by the interlayer distance and affected by the stacking pattern of graphene and CH 3 NH 3 PbI 3 . The 3D charge density differences present the build-in internal electric field from graphene to CH 3 NH 3 PbI 3 after interface equilibrium and thus, a low n -type Schottky barrier is needed for high efficient charge transferring in the interface. The possible mechanism of the band edge modulations in the heterojunctions and corresponding photoinduced charge transfer processes are also described. [ABSTRACT FROM AUTHOR]

The manipulation of the constituents of novel hetero-photocatalysts is an effective method for improving photocatalytic efficiency, but a theoretical understanding of the relationship between interlayer interaction and photocatalytic activity is still lacking. Herein, the interfacial interactions and electronic properties of MoS2/graphene oxide (GO) heterojunctions with various O concentrations were explored systematically by first-principles calculations. The results indicate that MoS2 and GO can form a stable van der Waals heterojunction, and enhance the built-in internal electric field from GO to the MoS2 surface with the increase in O concentration after interfacial equilibrium. It is inferred that the photogenerated electrons and holes naturally accumulate in the conduction band of GO and the valence band of MoS2, respectively, under the built-in internal electric field driving, indicating the formation of direct Z-scheme heterojunctions. In addition, a red shift of the light absorption edge and the shift up of the conduction band edge of MoS2/GO heterojunctions are observed with an increase in O concentration. It can be concluded that the O atom plays a crucial role in the energy band alignment of MoS2/GO heterojunctions for the improvement of photocatalytic performance. These results are beneficial to understand and design layered MoS2/GO photocatalytic systems or as cocatalysts with other semiconductors. [ABSTRACT FROM AUTHOR]

• Charge redistribution on the interface formed an interfacial internal electric field. • SnO x decreased work function of Sn-BiOCl and improved its photocatalytic reducibility. • Oxygen vacancies and internal electric field synergistically improved light absorption and charge separation. • Photodegradation activity of Sn-BiOCl increased 14 times higher than that of BiOCl. Solar-to-chemical energy conversion is valuable and sustainable strategy for energy and environmental crisis through photocatalysis. The amorphous SnO x modified BiOCl (Sn-BiOCl) full-spectrum-responsive catalysts were designed and synthesized through solvothermal method. The introduced Sn regulates the growth of BiOCl to form ultrathin nanosheets with surface oxygen vacancies. And the surface modification of SnO x induces interfacial internal electric field via charge redistribution on the interface of BiOCl and SnO x to accelerate the photogenerated charge separation. The modification of SnO x decreased work function of Sn-BiOCl and thus elevated its conduction band and valence band simultaneously, leading enhanced photocatalytic reducibility with the improved generation rate of ·O 2 −. The surface SnO x and oxygen vacancies of Sn-BiOCl broadened light absorption range and enhanced photocatalytic performance synergistically, resulting in 14-fold increased photodegradation rate of phenol compared with pure BiOCl under full spectrum. This method is also able to expand to other metal ions (such as Fe3+, In3+ and Sb3+). This work provides a valuable concept in structure regulating for enhanced photocatalytic performance in the removal of organic pollutants by interfacial internal electric field and surface oxygen vacancies. [ABSTRACT FROM AUTHOR]

Aqueous Mn-ion batteries (MIBs) exhibit a promising development potential due to their cost-effectiveness, high safety, and potential for high energy density. However, the development of MIBs is hindered by the lack of electrode materials capable of storing Mn 2+ ions due to acidic manganese salt electrolytes and large ion radius. Herein, the tunnel-type structure of monoclinic VO 2 nanorods to effectively store Mn 2+ ions via a reversible (de)insertion chemistry for the first time is reported. Utilizing exhaustive in situ/ex situ multi-scale characterization techniques and theoretical calculations, the co-insertion process of Mn 2+ /proton is revealed, elucidating the capacity decay mechanism wherein high proton activity leads to irreversible dissolution loss of vanadium species. Further, the Grotthuss transfer mechanism of protons is broken via a hydrogen bond reconstruction strategy while achieving the modulation of the electric double-layer structure, which effectively suppresses the electrode interface proton activity. Consequently, the VO 2 demonstrates excellent electrochemical performance at both ambient temperatures and -20 °C, especially maintaining a high capacity of 162 mAh g -1 at 5 A g -1 after a record-breaking 20 000 cycles. Notably, the all-vanadium symmetric pouch cells are successfully assembled for the first time based on the "rocking-chair" Mn 2+ /proton hybrid mechanism, demonstrating the practical application potential., (© 2024 Wiley‐VCH GmbH.)

Calcium ion batteries (CIBs) are a promising energy storage device due to the low redox potential of the Ca metal and the abundant reserves of the Ca element. However, the large radius and divalent nature of Ca 2+ lead to its slow ion diffusion kinetics and the lack of suitable electrode materials for Ca storage. Here, a layered structure of Na 2 Ti 3 O 7 (NTO) is presented as an anode material for nonaqueous CIBs. This NTO anode demonstrates a high discharge capacity of 165 mA h g -1 at 100 mA g -1 and a remarkable capacity retention rate of 80%, even after 2000 cycles at 500 mA g -1 , surpassing the performance of all reported intercalation-type anode materials for CIBs. The NTO transfers to layered Ca VII Na IX Ti 3 O 7 (CNTO) with intercalation of Ca 2+ and extraction of Na + during the first discharge process. Then, the CNTO undergoes the reversible insertion/extraction of Ca 2+ during subsequent cycling. Additionally, density functional theory calculations reveal that NTO possesses a rapid two-dimensional diffusion pathway for Ca 2+ . Moreover, the full CIBs based on NTO as the anode further underscore its potential for CIBs. This work presents promising anode materials for CIBs, offering opportunities to promote the development of high-performance CIBs.

Zinc powder (Zn-P) anodes have significant advantages in terms of universality and machinability compared with Zn foil anodes. However, their rough surface, which has a high surface area, intensifies the uncontrollable growth of Zn dendrites and parasitic side reactions. In this study, an anti-corrosive Zn-P-based anode with a functional layer formed from a MXene and Cu-THBQ (MXene/Cu-THBQ) heterostructure is successfully fabricated via microfluidic-assisted 3D printing. The unusual anti-corrosive and strong adsorption of Zn ions using the MXene/Cu-THBQ functional layer can effectively homogenize the Zn ion flux and inhibit the hydrogen evolution reaction (HER) during the repeated process of Zn plating/stripping, thus achieving stable Zn cycling. Consequently, a symmetric cell based on Zn-P with the MXene/Cu-THBQ anode exhibits a highly reversible cycling of 1800 h at 2 mA cm -2 /1 mAh cm -2 . Furthermore, a Zn-organic full battery matched with a 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl organic cathode riveted on graphene delivers a high reversible capacity and maintains a long cycle life., (© 2023 Wiley-VCH GmbH.)

The corrosion, parasitic reactions, and aggravated dendrite growth severely restrict development of aqueous Zn metal batteries. Here, we report a novel strategy to break the hydrogen bond network between water molecules and construct the Zn(TFSI) 2 -sulfolane-H 2 O deep eutectic solvents. This strategy cuts off the transfer of protons/hydroxides and inhibits the activity of H 2 O, as reflected in a much lower freezing point (<-80 °C), a significantly larger electrochemical stable window (>3 V), and suppressed evaporative water from electrolytes. Stable Zn plating/stripping for over 9600 h was obtained. Based on experimental characterizations and theoretical simulations, it has been proved that sulfolane can effectively regulate solvation shell and simultaneously build the multifunctional Zn-electrolyte interface. Moreover, the multi-layer homemade modular cell and 1.32 Ah pouch cell further confirm its prospect for practical application., (© 2022 Wiley-VCH GmbH.)

An understanding of the high photocatalytic performance reported for MoS2/BiOI nanocomposite is far from satisfactory. Here, the interfacial interaction and electronic properties of a MoS2/BiOI heterostructure were investigated systematically for the first time by first-principle calculations incorporating a semi-empirical dispersion-correction scheme. Our results confirm the reasonable existence of van der Waals interactions and a favorable Z-scheme mechanism, based on the typical interfacial cohesive energy and the energy level lineup at the interface. Analyzing the charge density differences and work functions, the built-in electric field is formed along the direction from MoS2 to BiOI after the interface equilibrium, and facilitates the separation of photoinduced electron-hole pairs in the interface. Additionally, it can be inferred that the incorporation of MoS2 into BiOI increases the carrier mobility and improves light harvesting, in agreement with the previously reported experimental data. Our work provides an insight into the mechanism of the enhanced visible-light photocatalytic activity of a MoS2/BiOI heterostructure, and helps to design other new heterostructure combinations.

Magnetic BiOBr/Fe 3 O 4 /RGO composites with remarkable photocatalytic capability were prepared by a simple hydrothermal method to load 3D flower-like microspherical BiOBr onto the surface of Fe 3 O 4 /RGO. Under visible-light irradiation ( λ > 420 nm), the BiOBr/Fe 3 O 4 /RGO composite with 56% mass percentage of Fe 3 O 4 /RGO shows the optimal removal ability for Rhodamine B, and the total removal efficiency is 96%. The coupling of Fe 3 O 4 /RGO and BiOBr elevates the conduction band of BiOBr, which enhances the reduction level of BiOBr/Fe 3 O 4 /RGO composites. Ultimately, based on experiments and theoretical calculations, an n-type Schottky contact formed at the heterojunction interface between RGO doped with Fe 3 O 4 and BiOBr is proposed for photoexcited charge transfer. The RGO with great adsorptivity plays a major role in the photocatalysts composed of BiOBr, RGO and Fe 3 O 4 . Further, BiOBr/Fe 3 O 4 /RGO composites with permanent-magnetism can be recovered and reused easily by external magnetic field and maintain a total removal efficiency of 90% after four cycles., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Maximizing the activity of materials towards the alkaline hydrogen evolution reaction while maintaining their structural stability under realistic working conditions remains an area of active research. Herein, we report the first controllable surface modification of graphene(G)/V 8 C 7 heterostructures by nitrogen. Because the introduced N atoms couple electronically with V atoms, the V sites can reduce the energy barrier for water adsorption and dissociation. Investigation of the multi-regional synergistic catalysis on N-modified G/V 8 C 7 by experimental observations and density-functional-theory calculations reveals that the increase of electron density on the epitaxial graphene enable it to become favorable for H* adsorption and the subsequent reaction with another H 2 O molecule. This work extends the range of surface-engineering approaches to optimize the intrinsic properties of materials and could be generalized to the surface modification of other transition-metal carbides., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The manipulation of the constituents of novel hetero-photocatalysts is an effective method for improving photocatalytic efficiency, but a theoretical understanding of the relationship between interlayer interaction and photocatalytic activity is still lacking. Herein, the interfacial interactions and electronic properties of MoS 2 /graphene oxide (GO) heterojunctions with various O concentrations were explored systematically by first-principles calculations. The results indicate that MoS 2 and GO can form a stable van der Waals heterojunction, and enhance the built-in internal electric field from GO to the MoS 2 surface with the increase in O concentration after interfacial equilibrium. It is inferred that the photogenerated electrons and holes naturally accumulate in the conduction band of GO and the valence band of MoS 2 , respectively, under the built-in internal electric field driving, indicating the formation of direct Z-scheme heterojunctions. In addition, a red shift of the light absorption edge and the shift up of the conduction band edge of MoS 2 /GO heterojunctions are observed with an increase in O concentration. It can be concluded that the O atom plays a crucial role in the energy band alignment of MoS 2 /GO heterojunctions for the improvement of photocatalytic performance. These results are beneficial to understand and design layered MoS 2 /GO photocatalytic systems or as cocatalysts with other semiconductors.