Search

Constructing heterostructural photoanodes is attractive for elevating the photoelectrochemical (PEC) performance, however, it is a long‐standing challenge to achieve highly efficient interfacial charge transfer. Herein, a CoFe metal‐thiolate framework (CoFe MTF)/Fe2O3 photoanode connected by an interfacial Fe─O─N/S bond is designed to modulate the behavior of charge carriers and improve water oxidation performance. It is disclosed that this interfacial bond functions as a direct charge transfer bridge between shallow trap states of Fe2O3 and CoFe MTF, leading to prolonged carrier recombination lifetimes (85 ns for CoFe MTF/Fe2O3 compared to 37 ns for Fe2O3) and enhanced charge transfer efficiency. Alternatively, a robust interfacial electric field is established in the CoFe MTF/Fe2O3 p–n heterojunction, facilitating efficient charge transfer. As expected, the CoFe MTF/Fe2O3 photoanode exhibits significant enhancement in water oxidation, resulting in a three‐fold increase in photocurrent density compared to pristine Fe2O3. This study highlights the significance of designing interfacially bonded heterostructural photoelectrodes to regulate the transfer characters of charge carriers. [ABSTRACT FROM AUTHOR]

Phenolic compounds are ubiquitous in nature because of their unique physical and chemical properties and wide applications, which have received extensive research attention. Phenolic compounds represented by tannic acid (TA) play an important role at the nanoscale. TA with a polyphenol hydroxyl structure can chemically react with organic or inorganic materials, among which metal–phenolic networks (MPNs) formed by coordination with metal ions and polyphenol derivatives formed by interactions with organic matter, exhibit specific properties and functions, and play key roles in photo(electro)catalysis. In this paper, we first introduce the fundamental properties of TA, then summarize the factors influencing the properties of MPNs and structural transformation of polyphenol-derived materials. Subsequently, the functions of MPNs and polyphenol derivatives in photo(electro)catalysis reactions are summarized, encompassing improving interfacial charge carrier separation, accelerating surface reaction kinetics, and enhancing light absorption. Finally, this article provides a comprehensive overview of the challenges and outlook associated with MPNs. Additionally, it presents novel insights into their stability, mechanistic analysis, synthesis, and applications in photo(electro)catalysis. [ABSTRACT FROM AUTHOR]

Cooperatively coupling efficient photocatalytic hydrogen (H2) evolution with simultaneous organic transformations into value-added chemicals is a promising strategy for addressing global energy and environmental challenges. Herein, a nitrogen-vacancy-rich Ti3C2Tx/g-C3N4 (TC/CN) Schottky junction is developed as an efficient photocatalyst for the simultaneous reduction of water to H2 and oxidation of furfuryl alcohol to furfural by utilizing photogenerated electrons and holes. Experimental results and density functional theory calculations demonstrate that the Schottky junctions created by interfacial N–Ti bonding between CN and TC facilitate efficient directional transfer of carriers while preventing electron backflow, thereby boosting separation of photogenerated electron–hole pairs. Further, the incorporation of nitrogen vacancies into TC/CN can provide active sites to enhance reactant adsorption and activation, thereby facilitating hole-mediated photooxidation activity towards furfuryl alcohol on the valence band of CN. As expected, the optimized TC/CN heterostructure exhibits a highly stable photocatalytic activity for H2 coupled furfural, with rates of 1.17 and 1.22 mmol g−1 h−1, respectively, which are 3.7 and 3.8 times higher than pure g-C3N4. The photocatalytic oxidation mechanism of the carbon-centered radical pathway was confirmed through control experiments, in situ EPR spectra, and theoretical studies. This ingenious work provides insightful guidance for the rational design of a dual-functional photocatalyst that can efficiently reduce water while selectively synthesizing organic compounds. [ABSTRACT FROM AUTHOR]

Incorporating metal nanodots (NDs) into heterostructures for high charge separation and transfer capacities is one of the most effective strategies for improving their photocatalytic activities. However, controlling the space distribution of metal NDs for optimizing charge transport pathways remains a significant challenge, particularly in two-dimensional (2D) face-to-face heterostructures. Herein, we develop a simple targeted self-reduction strategy for selectively loading Ru NDs onto the Ti3−xC2Ty (TC) surface of 2D TC/g-C3N4 (CN) heterojunction based on the reductive Ti vacancy defects creatively increased during the preparation of TC/CN by reducing calcination. Notably, the optimized Ru/TC/CN photocatalyst exhibits an outstanding H2 evolution rate of 3.21 mmol·g−1h−1 and a high apparent quantum efficiency of 30.9% at 380 nm, which is contributed by the unidirectional transfer of the photogenerated electrons from CN to Ru active sites (CN → TC → Ru) and the suppressed backflow of electrons from Ru sites to CN, as revealed by comprehensive characterizations and density functional theory (DFT) calculations. This work provides a novel strategy for synthesizing the highly efficient photocatalysts with a controllable charge transfer paths, which will boost the development of photocatalysis. [ABSTRACT FROM AUTHOR]

Rational design hybrid nanostructure photocatalysts with efficient charge separation and transfer, and good solar light harvesting ability have critical significance for achieving high solar‐to‐chemical conversion efficiency. Here a highly active and stable composite photocatalyst is reported by integrating ultrathin ZnIn2S4 nanosheets on surface of hollow CdS cube to form the cube‐in‐cube structure. Experimental results combined with density functional theory calculations confirm that the Z‐scheme ZnIn2S4/CdS heterojunction is formed, which highly boosts the charge separation and transfer under the local‐electric‐field at semiconductor/semiconductor interface, and thus prolongs their lifetimes. Moreover, such a structure affords the highly enhanced light‐harvesting property. The optimized ZnIn2S4/CdS nanohybrids exhibit superior H2 generation rate under visible‐light irradiation (λ ≥ 420 nm) with excellent photochemical stability during 20 h continuous operation. [ABSTRACT FROM AUTHOR]

Designing an architecture with the ability to temporarily capture one kind of charge carrier has a critical role to play in enhancing the performance of photocatalytic reactions. Here, we report that SrTiO3 nanofibers that have been treated with a brief method of H2 calcination in an H2/N2 atmosphere (denoted as STO-NH) form oxygen vacancies (OVs) and achieve significant improvement in performance in photocatalytic H2 production without the presence of cocatalysts. These OVs can trap photogenerated electrons, which inhibits the recombination of electrons and holes in both the surface and the bulk, thus improving the photocatalytic decomposition of water. Moreover, the concentration of surface OVs in STO-NH presents volcanic characteristics: the increase with rise in hydrogenation temperature, with a consequent increase in catalytic activity, indicates well-controlled formation of OVs. The existence and concentration of the OVs in STO-NH photocatalysts are investigated qualitatively through electron paramagnetic resonance, high-resolution transmission electron microscope and photoluminescence emission spectra. A reasonable photocatalytic mechanism is proposed that we expect to be able to provide significant guidance for future study. [ABSTRACT FROM AUTHOR]

The construction of integrated heterojunction system photoelectrodes for solar energy conversion is indubitably an efficient alternative due to their effectiveness in charge separation and optimizing the ability for reduction and oxidation reactions. Here, an integrated photoanode constructed with carbon quantum dot (CQD) sensitized Ti:Fe2O3@GCNN (where GCNNs are graphitic carbon nitride nanosheets) core–shell nanoarrays is demonstrated, showing an excellent photocurrent density as high as 3.38 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (VRHE), 2-fold higher than that of pristine Ti:Fe2O3, which is superior over that of recently reported promising photoanodes. In this ternary system (Ti:Fe2O3@GCNN-CQDs), each component plays a specific role in the process towards superior PEC water oxidation: (i) the vectorial hole transfer of Ti:Fe2O3→ g-C3N4→ CQDs; (ii) the introduction of CQDs leads to high catalytic activity for H2O2 decomposition contributing a high rate activity for water oxidation via a two-step-two-electron water-splitting process; (iii) the favorable electron transport behavior of CQDs. This controlled structure design represents one scalable alternative toward the development of photoanodes for high-efficiency water splitting. [ABSTRACT FROM AUTHOR]

Sunlight-driven water splitting using light-absorbing semiconductor-based materials is an ongoing strategy to overcome the world-wide environmental pollution and energy crisis. The construction of core–shell-type nanostructures by coupling of the earth-abundant hydrogen generation catalyst Mo2C to the good photoabsorber CdS may be the best combination for photocatalytic hydrogen generation reaction. Thus, in this work, core–shell nanorods consisting of a CdS core and a Mo2C–C shell have been designed and synthesized for the first time. The as-prepared CdS@Mo2C–C nanorods display an excellent hydrogen generation rate of 17.24 mmol h−1 g−1 relative to pure CdS, which may result from the unique one-dimensional nanostructure, the strong interfacial interaction between the core and shell materials, as well as the broadened visible-light absorption range. What's more, the existence of C layers in the core–shell nanorods can facilitate transfer of the photogenerated holes to the outer shell of Mo2C–C, and thus protect the inner CdS from photocorrosion to finally achieve high photostability of the catalyst. [ABSTRACT FROM AUTHOR]

Hematite (α‐Fe2O3) as a photoanode material for photoelectrochemical (PEC) water splitting suffers from the two problems of poor charge separation and slow water oxidation kinetics. The construction of p–n junction nanostructures by coupling of highly stable Co3O4 in aqueous alkaline environment to Fe2O3 nanorod arrays with delicate energy band positions may be a challenging strategy for efficient PEC water oxidation. It is demonstrated that the designed p‐Co3O4/n‐Fe2O3 junction exhibits superior photocurrent density, fast water oxidation kinetics, and remarkable charge injection and bulk separation efficiency (ηinj and ηsep), attributing to the high catalytic behavior of Co3O4 for the oxygen evolution reaction as well as the induced interfacial electric field that facilitates separation and transportation of charge carriers. In addition, a cocatalyst of cobalt phosphate (Co‐Pi) is introduced, which brings the PEC performance to a high level. The resultant Co‐Pi/Co3O4/Ti:Fe2O3 photoanode shows a photocurrent density of 2.7 mA cm−2 at 1.23 VRHE (V vs reversible hydrogen electrode), 125% higher than that of the Ti:Fe2O3 photoanode. The optimized ηinj and ηsep of 91.6 and 23.0% at 1.23 VRHE are achieved on Co‐Pi/Co3O4/Ti:Fe2O3, respectively, corresponding to the 70 and 43% improvements compared with those of Ti:Fe2O3. Furthermore, Co‐Pi/Co3O4/Ti:Fe2O3 shows a low onset potential of 0.64 VRHE and long‐time PEC stability. A well‐designed Co‐Pi/Co3O4/Ti:Fe2O3 photoanode displays efficient charge separation and transportation efficiency due to the induced interfacial electric field in the Co3O4/Ti:Fe2O3 p–n junction, as well as the fast water oxidation kinetics deriving from the high catalytic behavior of Co3O4 and Co‐Pi. [ABSTRACT FROM AUTHOR]

Doping transition metal oxide spinels with metal ions represents a significant strategy for optimizing the electronic structure of electrocatalysts. Herein, a bimetallic Fe and Ru doping strategy to fine-tune the crystal structure of CoV 2 O 4 spinel for highly enhanced oxygen evolution reaction (OER) is presented performance. The incorporation of Fe and Ru is observed at octahedral sites within the CoV 2 O 4 structure, effectively modulating the electronic configuration of Co. Density functional theory calculations have confirmed that Fe acts as a novel reactive site, replacing V. Additionally, the synergistic effect of Fe, Co, and Ru effectively optimizes the Gibbs free energy of the intermediate species, reduces the reaction energy barrier, and accelerates the kinetics toward OER. As expected, the best-performing CoVFe 0.5 Ru 0.5 O 4 displays a low overpotential of 240 mV (@10 mA cm -2 ) and a remarkably low Tafel slope of 38.9 mV dec -1 , surpassing that of commercial RuO 2 . Moreover, it demonstrates outstanding long-term durability lasting for 72 h. This study provides valuable insights for the design of highly active polymetallic spinel electrocatalysts for energy conversion applications., (© 2024 Wiley‐VCH GmbH.)

Objective: To observe the meridian-acupoint reactions of foot three yin meridians in primary dysmenorrhea(PD) and secondary dysmenorrhea(SD) patients, so as to summarize the rules of meridian-acupoint reaction and acupoints selection., Methods: Thirty-five patients with PD (PD group), 34 patients with SD (SD group) and 35 healthy subjects (healthy group) were recruited. The compression method was used to examine the lower leg segment of the foot three yin meridians. Positive reactions(palpable skin changes, including cords, nodules, depressions) and tenderness of meridians and acupoints were recorded. The visual analogue scale (VAS) was used to evaluate the tenderness severity of acupoints., Results: Compared with the healthy group, the probability of positive reactions and tenderness in foot three yin meridians were higher in PD and SD groups ( P <0.01, P <0.05). Compared with the PD group, the probability of positive reactions in Spleen and Liver Meridians were higher in the SD group, with higher probability of tenderness in Liver Meridian( P <0.05). The probability of positive reactions and tenderness in the Spleen Meridian of PD and SD groups was significantly higher than that in the Kidney Meridian ( P <0.01), while the probability of tenderness in the Spleen Meridian of the PD group was significantly higher than that in the Liver Meridian ( P <0.05). Positive reactions and tenderness were concentrated at Yinlingquan (SP9), Diji (SP8) and Sanyinjiao (SP6) of Spleen Meridian and Xiguan (LR7) and Ligou (LR5) in Liver Meridian of PD and SD groups. In comparison with the PD group, the probability of positive reactions, tenderness and VAS score of SP8 and LR5 of the SD group were higher ( P <0.05, P <0.01)., Conclusion: The positive reaction occurs most frequently in the Spleen Meridian, followed by the Liver Meridian, and least frequently in the Kidney Meridian. The acupoints with positive reaction are different between PD and SD, which suggests that the Spleen Meridian acupoints should be the main acupoints when treating the two kinds of dysmenorrhea, and acupoints should also be selected according to the meridian and acupoint examination results.

Boosting charge separation and transfer of photoanodes is crucial for providing high viability of photoelectrochemical hydrogen (H 2 ) generation. Here, a structural engineering strategy is designed and synthesized for uniformly coating an ultrathin CoFe bimetal-organic framework (CoFe MOF) layer over a BiVO 4 photoanode for boosted charge separation and transfer. The photocurrent density of the optimized BiVO 4 /CoFe MOF(NA) photoanode reaches a value of 3.92 mA cm -2 at 1.23 V versus reversible hydrogen electrode (RHE), up to 6.03 times that of pristine BiVO 4 , due to the greatly increased efficiency of charge transfer and separation. In addition, this photoanode records one onset potential that is considerably shifted negatively when compared to BiVO 4 . Transient absorption spectroscopy reveals that the CoFe MOF(NA) prolongs charge recombination lifetime by blocking the hole-transfer pathway from the BiVO 4 to its surface trap states. This work sheds light on boosting charge separation and transfer through structural engineering to enhance the photocurrent of photoanodes for solar H 2 production., (© 2022 Wiley-VCH GmbH.)

The design on synthesizing a sturdy, low-cost, clean, and sustainable electrocatalyst, as well as achieving high performance with low overpotential and good durability toward water splitting, is fairly vital in environmental and energy-related subject. Herein, for the first time the growth of sulfur (S) defect engineered self-supporting array electrode composed of metallic Re and ReS 2 nanosheets on carbon cloth (referred as Re/ReS 2 /CC) via a facile hydrothermal method and the following thermal treatment with H 2 /N 2 flow is reported. It is expected that, for example, the as-prepared Re/ReS 2 -7H/CC for the electrocatalytic hydrogen evolution reaction (HER) under acidic medium affords a quite low overpotential of 42 mV to achieve a current density of 10 mA cm -2 and a very small Tafel slope of 36 mV decade -1 , which are comparable to some of the promising HER catalysts. Furthermore, in the two-electrode system, a small cell voltage of 1.30 V is recorded under alkaline condition. Characterizations and density functional theory results expound that the introduced S defects in Re/ReS 2 -7H/CC can offer abundant active sites to advantageously capture electron, enhance the electron transport capacity, and weaken the adsorption free energy of H* at the active sites, being responsible for its superior electrocatalytic performance., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)