Homologous CoP/NiCoP Heterostructure on N‐Doped Carbon for Highly Efficient and pH‐Universal Hydrogen Evolution Electrocatalysis

Hydrogen evolution electrocatalysts can achieve sustainable hydrogen production via electrocatalytic water splitting; however, designing highly active and stable noble‐metal‐free hydrogen evolution electrocatalysts that perform as efficiently as Pt catalysts over a wide pH range is a challenging task. Herein, a new 2D cobalt phosphide/nickelcobalt phosphide (CoP/NiCoP) hybrid nanosheet network is proposed, supported on an N‐doped carbon (NC) matrix as a highly efficient and durable pH‐universal hydrogen evolution reaction (HER) electrocatalyst. It is derived from topological transformation of corresponding layer double hydroxides and graphitic carbon nitride. This 2D CoP/NiCoP/NC catalyst exhibits versatile HER electroactivity with very low overpotentials of 75, 60, and 123 mV in 1 m KOH, 0.5 m H₂SO₄, and 1 m PBS electrolytes, respectively, delivering a current density of 10 mA cm^?2 for HER. Such impressive HER performance of the hybrid electrocatalyst is mainly attributed to the collective effects of electronic structure engineering, strong interfacial coupling between CoP and NiCoP in heterojunction, an enlarged surface area/exposed catalytic active sites due to the 2D morphology, and conductive NC support. This method is believed to provide a basis for the development of efficient 2D electrode materials with various electrochemical applications.     

Spatially Separated CdS Shells Exposed with Reduction Surfaces for Enhancing Photocatalytic Hydrogen Evolution

To the photocatalytic H₂ evolution, the exposure of a reduction surface over a catalyst plays an important role for the reduction of hydrogen protons. Here, this study demonstrates the design of a noble‐metal‐free spatially separated photocatalytic system exposed with reduction surfaces (MnO_x @CdS/CoP) for highly solar‐light‐driven H₂ evolution activity. CoP and MnO_x nanoparticles are employed as the electron and hole collectors, which are selectively anchored on the outer and inner surface of CdS shells, respectively. Under solar light irradiation, the photogenerated holes and electrons can directionally move to the MnO_x and CoP, respectively, leading to the exposure of a reduction surface. As a result, the H₂ evolution increases from 32.0 to 238.4 µmol h^?1, which is even higher than the activity of platinum‐loaded photocatalyst (MnO_x @CdS/Pt). Compared to the pure CdS with serious photocorrosion, the MnO_x @CdS/CoP maintains a changeless activity for the H₂ evolution and rhodamine B degradation, even after four cycles. The research provides a new strategy for the preparation of spatially separated photocatalysts with a selective reduction surface.     

Localized Surface Plasmon Resonance Enhanced Photocatalytic Hydrogen Evolution via Pt@Au NRs/C3N4 Nanotubes under Visible‐Light Irradiation

Au nanorods (NRs) decorated carbon nitride nanotubes (Au NRs/CNNTs) photocatalysts have been designed and prepared by impregnation–annealing approach. Localized surface plasmon resonance (LSPR) peaks of Au NRs can be adjusted by changing the aspect ratios, and the light absorption range of Au NRs/CNNTs is extended to longer wavelength even near‐infrared light. Optimal composition of Pt@Au NR₇₆₉/CNNT₆₅₀ has been achieved by adjusting the LSPR peaks of Au NRs and further depositing Pt nanoparticles (NPs), and the photocatalytic H₂ evolution rate is 207.0 µmol h^?1 (20 mg catalyst). Preliminary LSPR enhancement photocatalytic mechanism is suggested. On one hand, LSPR of Au NRs is beneficial for visible‐light utilization. On the other hand, Pt NPs and Au NRs have a synergetic enhancement effect on photocatalytic H₂ evolution of CNNTs, in which the local electromagnetic field can improve the photogenerated carrier separation and direct electron transfer increases the hot electron concentration while Au NRs as the electron channel can well restrain charge recombination, finally Pt as co‐catalyst can boost H⁺ reduction rate. This work provides a new way to develop efficient photocatalysts for splitting water, which can simultaneously extend light absorption range and facilitate carrier generation, transportation and reduce carrier recombination.     

Unique PCoN Surface Bonding States Constructed on g‐C3N4 Nanosheets for Drastically Enhanced Photocatalytic Activity of H2 Evolution

Developing high‐efficiency and low‐cost photocatalysts by avoiding expensive noble metals, yet remarkably improving H₂ evolution performance, is a great challenge. Noble‐metal‐free catalysts containing Co(Fe)?N?C moieties have been widely reported in recent years for electrochemical oxygen reduction reaction and have also gained noticeable interest for organic transformation. However, to date, no prior studies are available in the literature about the activity of N‐coordinated metal centers for photocatalytic H₂ evolution. Herein, a new photocatalyst containing g‐C₃N₄ decorated with CoP nanodots constructed from low‐cost precursors is reported. It is for the first time revealed that the unique P(δ^?)?Co(δ⁺)?N(δ^?) surface bonding states lead to much superior H₂ evolution activity (96.2 µmol h^?1) compared to noble metal (Pt)‐decorated g‐C₃N₄ photocatalyst (32.3 µmol h^?1). The quantum efficiency of 12.4% at 420 nm is also much higher than the record values (≈2%) of other transition metal cocatalysts‐loaded g‐C₃N₄. It is believed that this work marks an important step toward developing high‐performance and low‐cost photocatalytic materials for H₂ evolution.     

Unique P?Co?N Surface Bonding States Constructed on g‐C3N4 Nanosheets for Drastically Enhanced Photocatalytic Activity of H2 Evolution

Developing high‐efficiency and low‐cost photocatalysts by avoiding expensive noble metals, yet remarkably improving H₂ evolution performance, is a great challenge. Noble‐metal‐free catalysts containing Co(Fe)? N? C moieties have been widely reported in recent years for electrochemical oxygen reduction reaction and have also gained noticeable interest for organic transformation. However, to date, no prior studies are available in the literature about the activity of N‐coordinated metal centers for photocatalytic H₂ evolution. Herein, a new photocatalyst containing g‐C₃N₄ decorated with CoP nanodots constructed from low‐cost precursors is reported. It is for the first time revealed that the unique P(δ^?)? Co(δ⁺)? N(δ^?) surface bonding states lead to much superior H₂ evolution activity (96.2 µmol h^?1) compared to noble metal (Pt)‐decorated g‐C₃N₄ photocatalyst (32.3 µmol h^?1). The quantum efficiency of 12.4% at 420 nm is also much higher than the record values (≈2%) of other transition metal cocatalysts‐loaded g‐C₃N₄. It is believed that this work marks an important step toward developing high‐performance and low‐cost photocatalytic materials for H₂ evolution.     

In Situ Grown Pristine Cobalt Sulfide as Bifunctional Photocatalyst for Hydrogen and Oxygen Evolution

Herein, transition metal chalcogenides of pristine cobalt sulfides are rationally designed to act as robust bifunctional photocatalysts for visible‐light‐driven water splitting for the first time. Through moderate solvothermal route, cobalt sulfides are synthesized in situ growth and observed by scanning electron microscope image analysis. Noteworthily, 3D hierarchical cobalt sulfides acting as bifunctional photocatalysts are implemented to catalyze the visible‐light‐driven oxygen evolution reaction and hydrogen evolution reaction. This efficient, earth‐abundant, and nonnoble water splitting catalyst for artificial photosynthesis is thoroughly analyzed by various spectroscopic techniques with the aim of investigating its photocatalytic mechanism under visible‐light illumination. The main catalyst of CoS‐2 exhibits considerable H₂ evolution rate of 1196 µmol h^?1 g^?1 and O₂ yield of 63.5%. The efficient activity is attributed to the effective electron transfer between the photosensitizer and catalyst, which is verified by transient absorption experiments. The effective electron transfer between the photosensitizer and catalyst during water oxidation is verified by the dramatic decline of [Ru(bpy)₃]³⁺ concentration in the presence of the catalyst CoS‐2. At the same time, transient absorption experiments support a rapid electron transfers from ³EY* (excited photosensitizer eosin‐Y) to the catalyst CoS‐2 for efficient hydrogen evolution.     

Bifunctional Hydrogen Production and Storage on 0D–1D Heterojunction of Cd0.5Zn0.5S@Halloysites

Development of efficient solar‐driven hydrogen (H₂) evolution and H₂ storage materials is challenging. Sulfide nanocatalysts show large potential for H₂ production, but suffer from the drawbacks of inefficient charge separation, serious photocorrosion, and easy agglomeration. Herein, a 0D–1D satellite‐core ethylenediaminetetraacetic acid (EDTA)‐bridged Cd_0.5Zn_0.5S@halloysite nanotubes tertiary structure is designed via facile in situ assembly, which settles all the above‐mentioned issues and achieves exceptional and stable photocatalytic H₂ evolution and storage. Significantly, EDTA grafted on halloysites as the hole (h⁺) traps steers the photogenerated h⁺ and electrons (e^?) from Cd_0.5Zn_0.5S separately to halloysites and outer surface Pt sites, achieving efficient directional separation between h⁺ and e^? and inhibiting the h⁺‐dominated photocorrosion occurring on Cd_0.5Zn_0.5S. Benefiting from these advantages, the hierarchy shows an unprecedented photocatalytic H₂ evolution rate of 25.67 mmol g^?1 h^?1 with a recording apparent quantum efficiency of 32.29% at λ = 420 nm, which is seven‐fold that of Cd_0.5Zn_0.5S. Meanwhile, an H₂ adsorption capacity of 0.042% is achieved with the room temperature of 25 °C and pressure of 2.65 MPa. This work provides a new perspective into designing hierarchical structure for H₂ evolution, and proposes an integration concept for H₂ evolution and storage.     

Ice‐Assisted Synthesis of Black Phosphorus Nanosheets as a Metal‐Free Photocatalyst: 2D/2D Heterostructure for Broadband H2 Evolution

A 2D/2D heterojunction of black phosphorous (BP)/graphitic carbon nitride (g‐C₃N₄) is designed and synthesized for photocatalytic H₂ evolution. The ice‐assisted exfoliation method developed herein for preparing BP nanosheets from bulk BP, leads to high yield of few‐layer BP nanosheets (≈6 layers on average) with large lateral size at reduced duration and power for liquid exfoliation. The combination of BP with g‐C₃N₄ protects BP from oxidation and contributes to enhanced activity both under λ > 420 nm and λ > 475 nm light irradiation and to long‐term stability. The H₂ production rate of BP/g‐C₃N₄ (384.17 µmol g^?1 h^?1) is comparable to, and even surpasses that of the previously reported, precious metal‐loaded photocatalyst under λ > 420 nm light. The efficient charge transfer between BP and g‐C₃N₄ (likely due to formed N? P bonds) and broadened photon absorption (supported both experimentally and theoretically) contribute to the excellent photocatalytic performance. The possible mechanisms of H₂ evolution under various forms of light irradiation is unveiled. This work presents a novel, facile method to prepare 2D nanomaterials and provides a successful paradigm for the design of metal‐free photocatalysts with improved charge‐carrier dynamics for renewable energy conversion.     

Mo-Modified ZnIn2S4@NiTiO3 S-Scheme Heterojunction with Enhanced Interfacial Electric Field for Efficient Visible-Light-Driven Hydrogen Evolution

Designing and developing visible-light-responsive materials for solar to chemical energy is an efficient and promising approach to green and sustainable carbon-neutral energy systems. Herein, a facile in situ growth hydrothermal strategy using Mo-modified ZnIn₂S₄ (Mo-ZIS) nanosheets coupled with NiTiO₃ (NTO) microrods to synthesize multifunctional Mo-modified ZIS wrapped NTO microrods (Mo-ZIS@NTO) photocatalyst with enhanced interfacial electric field (IEF) effect and typical S-scheme heterojunction is reported. Mo-ZIS@NTO catalyst possesses wide-spectrum light absorption properties, excellent visible light-to-thermal energy effect, electron mobility, charges transfer, and strong IEF and exhibits excellent solar-to-chemical energy conversion for efficient visible-light-driven photocatalytic hydrogen evolution. Notably, the engineered Mo_1.4-ZIS@NTO catalyst exhibits superior performance with H₂ evolution rate of up to 14.06 mmol g⁻¹ h^{− 1} and the apparent quantum efficiency of 44.1% at 420 nm. The scientific explorations provide an in-depth understanding of microstructure, S-scheme heterojunction, enhanced IEF, Mo-dopant facilitation effect. Moreover, the theoretical simulations verify the critical role of Mo element in promoting the adsorption and activation of H₂O molecules, modulating the H adsorption behavior on active S sites, and thus accelerating the overall catalytic efficiency. The photocatalytic hydrogen evolution mechanism via S-scheme heterojunction with adjustable IEF regulation over Mo_1.4-ZIS@NTO is also demonstrated.     

Atomically Dispersed Silver-Cobalt Dual-Metal Sites Synergistically Promoting Photocatalytic Hydrogen Evolution

Regulating the coordination environment of single-atom sites is of high necessity to promote the catalytic performances of the photocatalysts. Herein, the preparation of atomically dispersed Co-Ag dual-metal sites anchored on P-doped carbon nitride (Co₁Ag₁-PCN) via supramolecular and solvothermal approaches is reported, which demonstrates desirable performance for photocatalytic H₂ evolution from water splitting. The optimal Co₁Ag₁-PCN catalyst achieves a remarkable hydrogen production rate of 1190 µmol g⁻¹ h⁻¹ with an apparent quantum yield (AQY) of 1.49% at 365 nm, superior to most of the newly reported metal-N-coordinated photocatalysts. Systematic experimental characterizations and density functional theoretic studies attribute the enhanced photocatalytic activity to the synergistic effect of Co-Ag dual sites with exclusive coordination configuration of Co-N₆ and Ag-N₂C₂, which enhances the charge density and promotes oriented electrons transport to the metal centers with reduced free energy barriers by facilitating the formation of H* intermediates as the key step in hydrogen evolution. This study reveals a versatile strategy to tailor the electronic structures of dual-metal sites with synergies by engineering the neighboring coordination environment.     

Targeted Exfoliation and Reassembly of Polymeric Carbon Nitride for Efficient Photocatalysis

Switching the properties of photocatalytic materials targetedly and exerting these advantages fully in different photoredox reactions are crucial for the sufficient utilization of solar energy but still presents a significant challenge. This study presents a facile, green, and reversible exfoliation–reassembly strategy to switch the features of polymeric carbon nitride (CN) favorably for different photoredox reactions. The giant expansion effect of in situ‐generated H₂O molecules confined to the interlayer results in the mass production of ultrathin polymeric CN nanosheets, giving a high yield, i.e., up to 48%, of ultrathin nanosheets in a mild solution (pH ≈1.3). Interestingly, the exfoliation–reassembly process as well as the properties of CN are largely reversible via alternating the interlayer groups. Moreover, the exfoliated and reassembled CN achieve a superior photocatalytic activity for isopropanol degradation (acetone: 345 µmol h^?1; CO₂: 23 µmol h^?1) and H₂ evolution (1370 µmol h^?1), resulting in a high apparent quantum yield of 27% and 46%, respectively, at ≈420 nm.     

Delocalized Electron Accumulation at Nanorod Tips: Origin of Efficient H2 Generation

Photocatalytic hydrogen (H₂) evolution requires efficient electron transfer to catalytically active sites in competition with charge recombination. Thus, controlling charge‐carrier dynamics in the photocatalytic H₂ evolution process is essential for optimized photocatalyst nanostructures. Here, the efficient delocalization of electrons is demonstrated in a heterostructure consisting of optimized MoS₂ tips and CdS nanorods (M‐t‐CdS Nrs) synthesized by amine‐assisted oriented attachment. The heterostructure achieves photocatalytic H₂ activity of 8.44 mmol h^?1 g^?1 with excellent long‐term durability (>23 h) without additional passivation under simulated solar light (AM 1.5, 100 mW cm^?2). This activity is nearly two orders of magnitude higher than that of pure CdS Nrs. The impressive photocatalytic H₂ activity of M‐t‐CdS Nrs reflects favorable charge‐carrier dynamics, as determined by steady‐state PL and time‐correlated single photon counting correlation analysis at low temperature. The MoS₂ cocatalysts precisely located at the end of the CdS Nrs exhibit ultrafast charge transfer and slow charge recombination via spatially localized deeper energy states, resulting in a highly efficient H₂ evolution reaction in lactic acid containing an electrolyte.     

Cuprous iodide dose dependent passivation of MAPbI3 perovskite solar cells

MAPbI₃ has been considered as a candidate for the active layer of perovskite solar cells in recent years. We proposed a device model to investigate the contribution of cuprous iodide (CuI) to MAPbI₃ perovskite thin films to power conversion efficiency (PCE) and demonstrated that the dosage of CuI affects the grain size of thin films and the PCE. Through the results of the SEM analysis, we found that the grain boundaries of MAPbI₃ perovskite films decreased with increases in the dosage of CuI and the grain size increased significantly from 164 nm ± 49 nm–299 nm ± 127 nm. In addition, the results of the PL measurement showed that the PL intensity decreased after addition of CuI to the MAPbI₃ perovskite thin films, suggesting a reduction in the charge recombination. The XRD patterns indicated that the addition of CuI did not influence the main structure of the MAPbI₃ perovskite. Interestingly, CuI plays a key role in the passivation of defects in MAPbI₃ perovskite thin films, which can reduce non-radiative recombination and increase the fill factor and open-circuit voltage of the device. In this study, we adjusted the grain size and passivated the MAPbI₃ thin film by controlling the dosage of CuI. We also increased the power conversion efficiency from 10% to 13%. This type of perovskite solar cell provided a simple, low cost preparation process for practical applications.     

Molybdenum and Phosphorous Dual Doping in Cobalt Monolayer Interfacial Assembled Cobalt Nanowires for Efficient Overall Water Splitting

The necessity for better water splitting requires speedy development of efficient catalysts with high activity, long‐term stability, and cost effectiveness. In this work, a bifunctional catalyst originating from the interfacial assembly of a thin Mo,P‐codoped Co layer (≈50 nm) shelled Co nanowire (Co‐Mo‐P/CoNWs) network is fabricated via a facile approach. The catalyst exhibits low overpotentials of 0.08 and 0.27 V to reach a current response of 20 mA cm^?2 for the hydrogen evolution reaction and oxygen evolution reaction, respectively, together with long‐term stability in 1.0 m KOH medium. The outstanding performance is further demonstrated by a Co‐Mo‐P/CoNWs‐based electrolyzer, which enables a cell voltage of only 1.495 V to reach 10 mA cm^?2, superior to one derived from commercial (Pt/C + RuO₂/C) as well as to various reports recently published elsewhere. It is recognized that the formation of multiactive centers together with the increased active site number caused by Mo and P dual doping synergistically promote both hydrogen and oxygen evolution performance. Such a hybrid material opens a new approach for developing efficient and cost‐effective catalysts for water splitting application.     

Simultaneously Tuning Band Structure and Oxygen Reduction Pathway toward High-Efficient Photocatalytic Hydrogen Peroxide Production Using Cyano-Rich Graphitic Carbon Nitride

The demands for green production of hydrogen peroxide have triggered extensive studies in the photocatalytic synthesis, but most photocatalysts suffer from rapid charge recombination and poor 2e⁻ oxygen reduction reaction (ORR) selectivity. Here, a novel composite photocatalyst of cyano-rich graphitic carbon nitride g-C₃N₄ is fabricated in a facile manner by sodium chloride-assisted calcination on dicyandiamide. The obtained photocatalysts exhibit superior activity (7.01 mm  h⁻¹ under λ  ≥  420 nm, 16.05 mm  h⁻¹ under simulated sun conditions) for H₂O₂ production and 93% selectivity for 2e⁻ ORR, much higher than that of the state-of-the-art photocatalyst. The porous g-C₃N₄ with Na dopants and cyano groups simultaneously optimize two limiting steps of the photocatalytic 2e⁻ ORR: photoactivity, and selectivity. The cyano groups can adjust the band structure of g-C₃N₄ to achieve high activity. They also serve as oxygen adsorption sites, in which local charge polarization facilitates O₂ adsorption and protonation. With the aid of Na⁺, the O₂ is reduced to produce more superoxide radicals as the intermediate products for H₂O₂ synthesis. This work provides a facile approach to simultaneously tune photocatalytic activity and 2e⁻ ORR selectivity for boosting H₂O₂ production, and then paves the way for the practical application of g-C₃N₄ in environmental remediation and energy supply.     

Atomistic Structural Engineering of Conjugated Microporous Polymers Promotes Photocatalytic Biomass Valorization

Polymer photocatalysts have great promise for solar fuel production due to their flexible structural and functional designability. However, their photocatalytic efficiencies are still unsatisfactory, limited by their intrinsically large exciton binding energy and fast charge recombination. Herein, the atomistic structural engineering of donor–acceptor (D−A) polymer photocatalysts for enhanced charge separation and photocatalytic hydrogen production is proposed. By changing the electron affinity of the acceptor units, the electron delocalization and exciton binding energy of the polymeric networks can be readily tuned, resulting in enhanced charge separation efficiency and photocatalytic activity. The optimal sample shows the highest H₂ production rate of 3207 µmol g⁻¹ h⁻¹ in the presence of ascorbic acid as the sacrificial agent. Moreover, the photocatalytic H₂ production can be coupled with almost stoichiometrical conversion of 5-hydroxymethyl furfural to 2,5-diformylfuran.     

Synthesis of Leaf‐Vein‐Like g‐C3N4 with Tunable Band Structures and Charge Transfer Properties for Selective Photocatalytic H2O2 Evolution

Photocatalytic H₂O₂ evolution through two‐electron oxygen reduction has attracted wide attention as an environmentally friendly strategy compared with the traditional anthraquinone or electrocatalytic method. Herein, a biomimetic leaf‐vein‐like g‐C₃N₄ as an efficient photocatalyst for H₂O₂ evolution is reported, which owns tenable band structure, optimized charge transfer, and selective two‐electron O₂ reduction. The mechanism for the regulation of band structure and charge transfer is well studied by combining experiments and theoretical calculations. The H₂O₂ yield of CN4 (287 µmol h^?1) is about 3.3 times higher than that of pristine CN (87 µmol h^?1), and the apparent quantum yield for H₂O₂ evolution over CN4 reaches 27.8% at 420 nm, which is much higher than that for many other current photocatalysts. This work not only provides a novel strategy for the design of photocatalyst with excellent H₂O₂ evolution efficiency, but also promotes deep understanding for the role of defect and doping sites on photocatalytic activity.     

Pushing the Envelope: Achieving an Open‐Circuit Voltage of 1.18 V for Unalloyed MAPbI3 Perovskite Solar Cells of a Planar Architecture

After an overwhelmingly fast increase during the period from 2009 to 2016, the power conversion efficiency of hybrid perovskite solar cells levels at ≈22% during the past two years. Every small advance to theoretical limits of the photovoltaic metrics will significantly deepen the understanding of internal processes inside the perovskite solar cells. Here, by introducing chloroform as the antisolvent, the one‐step deposition method to fabricate methylammonium lead tri‐iodide (MAPbI₃) perovskite films under ambient air condition is optimized. With MAPbI₃ solar cells of a planar architecture, a record high V_oc of 1.18 V is obtained under simulated AM1.5 sunlight. The achievement helps pure MAPbI₃ to reestablish its potential as a model compound for research in hybrid perovskite solar cells. After systematic comparison on different electron transport layers (SnO₂ and TiO₂) and fluorine doped tin oxide (FTO) substrates of different roughness for photon trapping inside MAPbI₃ solar cells, the remaining 0.14 V V_oc loss is elucidated to be due to the poor luminescent property of the MAPbI₃ films.     

Oxygen Vacancy-Mediated Exciton Effect in Hierarchical BiOBr Enables Dichotomy of Energy Transfer and Electron Transfer in Photocatalysis

Using solar energy through green and simple artificial photosynthesis systems are considered as a promising way to solve the energy and environmental crisis. However, one of the important primary steps of photosynthesis, i.e., energy transfer, is long being ignored especially in inorganic semiconducting systems due to the small exciton binding energies. Herein, the simultaneous interrogation of the charge transfer and energy transfer steps in a photoexcitation process is proposed by utilizing few-layered nanosheet-assembled hierarchical BiOBr nanotubes with rich oxygen vacancies (OVs) as efficient multifunctional photocatalysts. Benefiting from the integrated 1D/2D structure and abundant OV defects, the excitonic effect strikes a delicate balance in the optimized BiOBr photocatalyst, showing not only improved charge carrier separation and transfer but also enhanced exciton generation. As a result, the hierarchical BiOBr nanotubes exhibit high efficiency toward photocatalytic CO₂ reduction with an impressive CO evolution rate of 135.6 µmol g⁻¹ h⁻¹ without cocatalyst or photosensitizer. The dominant reactive oxygen species of singlet oxygen (¹O₂) are discriminated for the first time, which originated from an energy transfer process, with electrophilic character, whereas the minor effect of superoxide anion radical (^•O₂⁻) with a nucleophilic rate-determining step in the photocatalytic aerobic oxidation of sulfides.     

Regulating the Metallic Cu–Ga Bond by S Vacancy for Improved Photocatalytic CO2 Reduction to C2H4

Artificial photosynthesis, which converts carbon dioxide into hydrocarbon fuels, is a promising strategy to overcome both global warming and energy crisis. Herein, the geometric position of Cu and Ga on ultra-thin CuGaS₂/Ga₂S₃ is oriented via a sulfur defect engineering, and the unprecedented C₂H₄ yield selectivity is ≈93.87% and yield is ≈335.67 µmol g⁻¹ h⁻¹. A highly delocalized electron distribution intensity induced by S vacancy indicates that Cu and Ga adjacent to S vacancy form Cu–Ga metallic bond, which accelerates the photocatalytic reduction of CO₂ to C₂H₄. The stability of the crucial intermediates (*CHOHCO) is attributed to the upshift of the d-band center of ultra-thin CGS/GS. The C–C coupling barrier is intrinsically reduced by the dominant exposed Cu atoms on the 2D ultra-thin CuGaS₂/Ga₂S₃ in the process of photocatalytic CO₂ reduction, which captures *CO molecules effectively. This study proposes a new strategy to design photocatalyst through defect engineering to adjust the selectivity of photocatalytic CO₂ reduction.