Efficient Photocatalytic Hydrogen Evolution Research Articles

In Situ Construction of Hollow Coral-Like Porous S-Doped g-C3N4/ZnIn2S4 S-Scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution.

The rational design of visible-light-responsive catalysts is crucial for converting solar energy into hydrogen energy to promote sustainable energy development. In this work, a C─S─C bond is introduced into g-C3N4 (CN) through S doping. With the help of the flexible C─S─C bond under specific stimuli, a hollow coral-like porous structure of S-doped g-C3N4 (S-CN) is synthesized for the first time. And an S-doped g-C3N4/ZnIn2S4 (S-CN/ZIS) heterojunction catalyst is in situ synthesized based on S-CN. S0.5-CN/ZIS exhibits excellent photocatalytic hydrogen evolution (PHE) efficiency (19.25mmol g-1 h-1), which is 2.7 times higher than that of the g-C3N4/ZnIn2S4 (CN/ZIS) catalyst (8.46mmol g-1 h-1), with a high surface quantum efficiency (AQE) of 34.43% at 420nm. Experiments and theoretical calculations demonstrate that the excellent photocatalytic performance is attributed to the larger specific surface area and porosity, enhanced interfacial electric field (IEF) effect, and appropriate hydrogen adsorption Gibbs free energy (ΔGH*). The synergistic effect of S doping and S-scheme heterojunction contributes to the above advancement. This study provides new insights and theoretical basis for the design of CN-based photocatalysts.

Oxidative and selective C–C cleavage of glycerol to glycolaldehyde with atom-like Cu on Cu-TiO2: Photocatalytic water reduction with concurrent glycerol oxidation in sunlight

Concurrent consumption of electrons and holes for the conversion of a biomass component to value added products represents a highly efficient and sustainable approach towards utilizing renewable energy, but difficult to achieve. The integration of hydrogen production with glycerol oxidation presents a novel and sustainable approach towards achieving a circular economy. In the current study, integration of atom-like Cu-clusters onto TiO2 substrate has been achieved using a facile photo-deposition technique (TC-PDO). Also, novel synthetic approaches have been employed to augment the surface coverage of Cu on TiO2 with atom-like clusters of Cu, either by borohydride treatment on TiO2 followed by Cu-deposition (TC-200) or oxygen-vacancy creation by UV illumination followed by Cu-deposition (TC-PDO). Increased dispersion and enhanced electronic integration of Cu with TiO2 lead to a corresponding increase in the efficiency of photocatalytic hydrogen evolution (13.8 mmol/h.g for TC-PDO at pH 9). Several atom-like Cu integrated with each TiO2 particle acts as photocatalytic reactor, and the same enhances electron-hole separation as well as activity. Sustainable aspect was also studied for TC-PDO up to 25 h at pH 9. Concurrently, glycerol oxidation displays the highest selectivity to C2 product (glycolaldehyde with 70 %) with a C–C cleavage. The investigation of this process holds significant potential for the extensive and simultaneous exploitation of electrons and holes in order to achieve water splitting and glycerol oxidation towards selective value-added products formation.

Modulation of catalyst interfacial electric field and charge transfer promotes NiS-modified CoWO4/ZnIn2S4 S-scheme heterojunction for efficient photocatalytic hydrogen evolution

The strategic post-synthetic modification of engineered S-scheme heterojunctions represents a potent and manipulable approach to significantly enhance photocatalytic activity. This study details the synthesis of innovative photocatalysts via the deposition of NiS nanoparticles onto S-scheme heterojunctions of CoWO4/ZnIn2S4 (CWO/ZIS-NiS), facilitated by solvothermal and photochemical methodologies. Under visible light irradiation, the hydrogen production rate of CWO/ZIS-NiS was 22.304 mmol g−1 h−1, which 14.7 times higher than that of the ZnIn2S4. XPS, EPR, SPV and DFT calculations were used to analyze the charge transfer path and the reasons for the performance improvement of the catalyst. The construction of the S-scheme CoWO4/ZnIn2S4 heterojunction, along with NiS modification to enhance the interfacial electric field (IEF) and act as a reaction center, was identified as the primary reason for the enhanced hydrogen production activity. This work provides guidance for the design of efficient photocatalytic systems using the synergistic effect between cocatalysts and S-scheme heterojunctions.

Facile Synthesis of Organic–Inorganic Hybrid Heterojunctions of Glycolated Conjugated Polymer‐TiO2−X for Efficient Photocatalytic Hydrogen Evolution

AbstractThe utilization of the organic–inorganic hybrid photocatalysts for water splitting has gained significant attention due to their ability to combine the advantages of both materials and generate synergistic effects. However, they are still far from practical application due to the limited understanding of the interactions between these two components and the complexity of their preparation process. Herein, a facial approach by combining a glycolated conjugated polymer with a TiO2−X mesoporous sphere to prepare high‐efficiency hybrid photocatalysts is presented. The functionalization of conjugated polymers with hydrophilic oligo (ethylene glycol) side chains can not only facilitate the dispersion of conjugated polymers in water but also promote the interaction with TiO2−X forming stable heterojunction nanoparticles. An apparent quantum yield of 53.3% at 365 nm and a hydrogen evolution rate of 35.7 mmol h−1 g−1 is achieved by the photocatalyst in the presence of Pt co‐catalyst. Advanced photophysical studies based on femtosecond transient absorption spectroscopy and in situ, XPS analyses reveal the charge transfer mechanism at type II heterojunction interfaces. This work shows the promising prospect of glycolated polymers in the construction of hybrid heterojunctions for photocatalytic hydrogen production and offers a deep understanding of high photocatalytic performance by such heterojunction photocatalysts.

2D Porphyrin-Based Covalent Organic Framework/PEG Composites: A Rational Strategy for Photocatalytic Hydrogen Evolution.

Two-dimensional porphyrin-based covalent organic frameworks (2D-por-COFs) have gained significant attention as attractive platforms for efficient solar light conversion into hydrogen production. Herein, we found that introducing transition metal zinc and polyethylene glycol (PEG) into 2D-por-COFs can effectively improve the photocatalytic hydrogen evolution performance. The photocatalytic hydrogen evolution rate of ZnPor-COF is 2.82 times higher than that of H2Por-COF. Moreover, ZnPor-COF@PEG has the highest photocatalytic hydrogen evolution efficiency, which is 1.31 times and 3.7 times that of pristine ZnPor-COF and H2Por-COF, respectively. The filling of PEG makes the layered structure of COFs more stable. PEG reduced the distortion and deformation of the carbon skeleton after the experiment of photocatalytic hydrogen evolution. The layered stacking and crystallization of 2D-por-COFs are also enhanced. Meanwhile, the presence of PEG also accelerates the transfer of excited electrons and enhances the photocatalytic hydrogen evolution activity. This strategy would provide valuable insights into the design of 2D-por-COFs as efficient solid photocatalysts for solar-driven hydrogen production. This article is protected by copyright. All rights reserved.

Single−atom Co anchored on covalent organic framework for remarkable photocatalytic hydrogen evolution efficiency

Single-atom catalysts (SACs) have attracted extensive attention because of their high atomic utilization and superior catalytic activity. Herein, single-atom Co has anchored on the β-ketoenamine-linked covalent organic framework (Tp-Tta COF) pores and used for remarkable photocatalytic hydrogen(H2) production under Ultraviolet–Visible light (UV–Vis light) irradiation. The single-atom Co is visualized by the aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC HAADF-STEM), and the C3–Co–N1 coordination structure is demonstrated by X-ray absorption fine structure (XAFS) measurements. The modified Co0.4-SAC/Tp-Tta COF shows a high photocatalytic H2 production of 1798.5 μmol g−1 h−1 and the Apparent quantum yield(AQY) is 3.02% at 420 nm. The improvement of the activity and stability of the photocatalyst is mainly attributed to the incorporation of Co single-atom that boosts the separation efficiency of photogenerated electron-hole pair and provides well-dispersed active sites. This study provides valuable insights into the development of UV–Vis light-responsive photocatalysts at the atomic level.

Rod-like Mn0.2Cd0.8S wrapped in foliated CeO2 promote efficient photocatalytic hydrogen evolution

The Mn0.2Cd0.8S/CeO2 heterojunction is synthesized by means of hydrothermal coupling. Short rod-like Mn0.2Cd0.8S is wrapped in leaf like CeO2 to construct a tight heterointerface, which stimulated the photocatalytic activity to the great extent. Due to the remarkable catalytic and electrochemical properties of Mn0.2Cd0.8S, the CeO2 surface active site is driven. CeO2 has excellent specific surface area, suitable pore volume aperture and Mn0.2Cd0.8S match to optimize the internal interface charge transfer path. At the same time, the heterointerface can coordinate the interface electron flow and promote the H2 reduction ability. The results show that the optimal hydrogen production of Mn0.2Cd0.8S/CeO2 with S-type heterostructure is 291.8 μmol, and the internal lattice and surface morphology of Mn0.2Cd0.8S/CeO2 are not easily damaged due to good catalytic stability. The photocatalytic mechanism of Mn0.2Cd0.8S/CeO2 is studied by finding the short distance interfacial charge transfer path and enriching the photogenerated electrons required for hydrogen evolution.

CdS-based Schottky junctions for efficient visible light photocatalytic hydrogen evolution

Heterojunctions photocatalysts play a crucial role in achieving high solar-hydrogen conversion efficiency. In this work, we mainly focus on the charge transfer dynamics and pathways for sulfides-based Schottky junctions in the photocatalytic water splitting process to clarify the mechanism of heterostructures photocatalysis. Sulfides-based Schottky junctions (CdS/CoP and CdS/1T-MoS2) were successfully constructed for photocatalytic water splitting. Because of the higher work function of CdS than that of CoP and 1T-MoS2, the direction of the built-in electric field is from CoP or 1T-MoS2 to semiconductor. Therefore, CoP and 1T-MoS2 can act as electrons acceptors to accelerate the transfer of photo-generated electron on the surface of CdS, thus improving the charge utilization efficiency. Meanwhile, CoP and 1T-MoS2 as active sites can also promote the water dissociation and lower the H+ reduction overpotential, thus contributing to the excellent photocatalytic hydrogen production activity (23.59 mmol·h−1·g−1 and 1195.8 mol·h−1·g−1 for CdS/CoP and CdS/1T-MoS2)

Enhanced visible light-driven hydrogen evolution in non-precious metal Ni2P/CdIn2S4 S-type heterojunction via rapid interfacial charge transfer

Strong light absorption capacity and effective separation of photogenerated charge are the keys to photocatalytic water decomposition, which is usually solved by constructing heterojunction methods. In this work, a novel n-n interwoven Ni2P/CdIn2S4 S-type heterojunction photocatalyst was prepared by hydrothermal method for efficient photocatalytic hydrogen evolution. After a series of characterization and performance tests, under simulated sunlight irradiation at 6 °C (λ > 420 nm), the hydrogen production of Ni2P/CdIn2S4 composite with the best performance can reach 6 mmol/g/h, which is not only 48 times that of pure CdIn2S4, but also 17.2 times that of the expensive metal Pt (CIS–1Pt). By changing the temperature, the hydrogen production of Ni2P/CdIn2S4 reached 8.7 mmol/g/h at 27.5 °C, while its AQY reached 7.7 % and 6.6 % at 420 nm and 475 nm, respectively. In addition, the possible photocatalytic mechanism was analyzed by band structure and XPS diagram, and it was confirmed that the internal electric field of the S-type heterojunction accelerated the photogenerated charge transition and enhanced the hydrogen evolution ability. This effectively compensated for the limitations of severe carrier recombination and low active sites in CdIn2S4 photocatalysts. Therefore, this work provides some help for the construction of non-precious metal S-type heterojunctions for photocatalytic hydrogen production.

Facile synthesis of CuOx-decorated TiO2 nanoparticles via oxygen-limited pyrolysis of Cu(II) complex for efficient photocatalytic hydrogen evolution

CuOx-decorated TiO2 (CuOx/TiO2) nanoparticles have been prepared by the pyrolysis of Cu(II) complex on TiO2 in an oxygen-limited atmosphere. A solution phase deposition method combined with freeze drying was employed for depositing the 2-methylimidazole-Cu(II) complex onto TiO2 nanoparticles. The effect of decoration of CuOx on TiO2 nanoparticles in terms of the crystal phase, morphology, chemical compositions, surface area, surface elemental states, optical absorption and emission properties, was investigated using a series of characterization tools. The oxygen-limited pyrolysis of 2-methylimidazole resulted in the reduction of partial Ti4+ and Cu2+ ions into Ti3+, Cu+ and Cu0 species, respectively. The surface decoration of CuOx was found to improve the separation and migration of photogenerated electron-hole pairs and increase the life time of excitons. Furthermore, the photocatalytic performance of CuOx/TiO2 nanoparticles was evaluated for hydrogen evolution in aqueous methanol solution under UV–visible light irradiation. The CuOx/TiO2 photocatalyst with the optimal cocatalyst loading achieved hydrogen evolution rate of 4.34 mmol h−1 g−1, with 71- and 5.5-fold enhancement in activity over neat TiO2 and CuOx/P25, respectively. It is expected that the combination of deposition and pyrolysis of 2-methylimidazole-Cu(II) complex could be an effective approach for the decoration of Cu and its oxides on other supports.

C3N5 nanosheets decorated with Cu–Pt alloy nanoparticles toward efficient photocatalytic hydrogen evolution

The construction of highly efficient photocatalysts for generating high-purity hydrogen (H2) through a sustainable water decomposition system is a feasible option to replace conventional non-renewable energy resources. Here, we report a simple chemical reduction approach to embed Cu–Pt alloy nanocrystals on the C3N5 (CN) matrix, creating a Schottky heterojunction. The structural morphology, crystal phase, light-harvesting capacity, and photo-electrochemical properties of as-prepared heterostructures were investigated. The uniformly anchored Cu–Pt alloy nanocrystals improve the photocatalytic H2 evolution (PHE) activity by promoting the separation and transfer of photogenerated carriers and inhibiting recombination. Meanwhile, the alloyed nanocrystals strengthen the absorption of incident light energy, inducing photothermal energy. This improves the charge carrier separation and promotes the surface reaction kinetics. The PHE performance of as-developed catalysts could be adjusted by optimizing the molar ratio of Cu/Pt ions. Among them, the optimal Cu1Pt3/CN photocatalyst yields a higher PHE performance (672.85 μmol g−1 h−1). Notably, the Cu1Pt3/CN catalyst also reveals an enhanced photocatalytic activity for H2 evolution in natural seawater. The possible PHE mechanism in CuPt/CN heterostructures is discussed toward the role of CuPt alloy deposition in boosting photocatalytic efficiency.

Coal-based carbon quantum dots modified Ni-MOF and Co/Zr-MOF heterojunctions for efficient photocatalytic hydrogen evolution

NS-CQDs were synthesized by a hydrothermal method using high-sulfur lignite as the carbon source. Modification of Ni-MOF and Co/Zr-MOF using NS-CQDs to explore the performance of composite photocatalysts for hydrogen production. It was found that NS-CQDs significantly enhanced the hydrogen precipitation performance of the composite photocatalysts compared with the MOFs catalysts alone, and the highest hydrogen precipitation rate of the novel composite photocatalyst 5%NS-CQDs/NCZ2 reached 3662.68 μmol g−1 h−1. It can be inferred from the conduction band and valence band positions of Ni-MOF, Co/Zr-MOF and NS-CQDs that a double S-type heterojunction is formed. The presence of thiophene and pyrrole nitrogen in NS-CQDs can promote electron transport, reduce the rate of electron-hole pair complexation, and improve the hydrogen evolution activity of the 5%NS-CQDs/NCZ2.

Linkage-Mediated Electronic Structure Modulation in Multicomponent Covalent Organic Frameworks for Dramatically Promoted Photocatalytic Hydrogen Evolution.

Linkage chemistry is an essential aspect to covalent organic framework (COF) applications; it is highly desirable to precisely modulate electronic structure mediated directly by linkage for efficient COF-based photocatalytic hydrogen evolution, which however, remains substantially challenging. Herein, as a proof of concept, a collection of robust multicomponent pyrene-based COFs with abundant donor-acceptor (D-A) interactions has been judiciously designed and synthesized through molecularly engineering linkage for photogeneration of hydrogen. Controlled locking and conversion of linkage critically contribute to continuously regulating COFs' electronic structures further to optimize photocatalytic activities. Remarkably, the well-modulated optoelectronic properties turn on the average hydrogen evolution rate from zero to 15.67 mmol g-1 h-1 by the protonated quinoline-linked COF decorated with the trifluoromethyl group (TT-PQCOF-CF3). Using diversified spectroscopy and theoretical calculations, we show that multiple modifications toward linkage synergistically lead to the redistribution of charge on COFs with extended π-conjugation and reinforced D-A effect, making TT-PQCOF-CF3 a promising material with significantly boosted carrier separation and migration. This study provides important guidance for the design of high-performance COF photocatalysts based on the strategy of linkage-mediated electronic structure modulation in COFs.

Microwave-Assisted Synthesis of SnO2@ZnIn2S4 Composites for Highly Efficient Photocatalytic Hydrogen Evolution.

This research successfully synthesized SnO2@ZnIn2S4 composites for photocatalytic tap water splitting using a rapid two-step microwave-assisted synthesis method. This study investigated the impact of incorporating a fixed quantity of SnO2 nanoparticles and combining them with various materials to form composites, aiming to enhance photocatalytic hydrogen production. Additionally, different weights of SnO2 nanoparticles were added to the ZnIn2S4 reaction precursor to prepare SnO2@ZnIn2S4 composites for photocatalytic hydrogen production. Notably, the photocatalytic efficiency of SnO2@ZnIn2S4 composites is substantially higher than that of pure SnO2 nanoparticles and ZnIn2S4 nanosheets: 17.9-fold and 6.3-fold, respectively. The enhancement is credited to the successful use of visible light and the facilitation of electron transfer across the heterojunction, leading to the efficient dissociation of electron-hole pairs. Additionally, evaluations of recyclability demonstrated the remarkable longevity of SnO2@ZnIn2S4 composites, maintaining high levels of photocatalytic hydrogen production over eight cycles without significant efficiency loss, indicating their impressive durability. This investigation presents a promising strategy for crafting and producing environmentally sustainable SnO2@ZnIn2S4 composites with prospective implementations in photocatalytic hydrogen generation.

Ohmic junction ZnIn2S4/MoP for efficient photocatalytic hydrogen evolution

In this paper, coupling MoP onto ZIS surface using solvothermal method to form ohmic heterojunction. The photocatalytic performance of ZIS/MoP is significantly better than that of ZIS and MoP monomers, and the hydrogen evolution efficiency of the composite material reaches 2.031 mmol g−1 h−1, 50 and 18 times the hydrogen production efficiency of MoP and ZIS. The quantum apparent efficiency (AQE) reaches 10.5 %. The improvement of the photocatalytic performance of ZIS/MoP is attributed to the generation of Ohmic heterojunctions. An Ohmic heterojunction is formed when MoP attaches to the surface of ZIS as an electron acceptor, In one aspect, the electron transfer path of Ohmic heterojunctions improves the separation efficiency of electrons and holes, enhances the charge transfer efficiency. ln the other aspect, ZIS greatly improves the visible light absorption of ZIS/MoP. To confirm the photocatalytic mechanism and Ohmic heterojunction structure, characterization methods such as X-ray photoelectron spectroscopy (XPS), ultraviolet electron spectroscopy (UPS), and band structure were used. This study aims to improve photocatalytic performance by designing and constructing ohmic heterojunctions, and provides a new design approach for improving photocatalytic performance.

Amorphous nitrogen-doped carbon layers forming the interfacial channel for rapid charge transfer in ZnIn2S4/BiVO4 Z-scheme photocatalyst for enhancing organic pollutants degradation with simultaneous hydrogen evolution

Efficient photocatalytic hydrogen evolution from the organic wastewater represents an ideal solution for simultaneously addressing energy shortages and environmental pollution. However, the sluggish transport of photogenerated carriers at contact interface poses a key obstacle to enhancing photocatalytic activity. Here, ZnIn2S4/BiVO4@N-C (ZIS/BVO@N-C) Z-scheme photocatalysts were successfully constructed by a simple hydrothermal-impregnation method. ZIS/BVO@N-C-10% demonstrated outstanding photocatalytic performance, achieving a hydrogen evolution rate of 2695.68 μmol·g−1·h−1 and a degradation rate of 492.96 mmol·g−1·h−1 under visible light, surpassing those of ZIS (851.52 μmol·g−1·h−1 and 174.83 mmol·g−1·h−1) and ZIS/BVO-10% (1228.98 μmol·g−1·h−1 and 277.78 mmol·g−1·h−1). Characterization results and density functional theory (DFT) calculations revealed that the introduction of the N-C layer reduced interfacial impedance and enhanced the strength of interfacial electric field, overcoming the interfacial barrier and improving the photogenerated separation and migration efficiency at the interface, and ultimately enhancing the photocatalytic activity of ZIS/BVO@N-C. Based on experimental and characterization results, the photocatalytic mechanism of ZIS/BVO@N-C Z-scheme has been proposed. Furthermore, ZIS/BVO@N-C exhibited excellent stability, highlighting its potential for practical applications. This work also presents a new strategy for designing highly active Z-scheme photocatalysts for organic wastewater treatment and simultaneous hydrogen energy recovery.

Surface vacancy engineering powered reverse cation exchange in preparing CuZnS hollow nanoboxs for efficient photocatalytic hydrogen evolution

The cation exchange technology plays a significant role in designing high-performance photocatalysts at atomic scale. However, the chemical kinetic energy barrier greatly limits the application of cation exchange strategies. Herein, an effective surface vacancy engineering powered reverse cation exchange strategy was exploited to realize energy-unfavored cation exchange reactions. Cu vacancies are created on the surface of Cu2-xS nanoboxs (Cu2-xS NBs), which are subsequently occupied by Zn2+ ions. A hollow CuZnS nanoboxs (CuZnS NBs) were successfully prepared for photocatalytic hydrogen evolution. The prepared CuZnS NBs has abundant interfacial Zn-S bonds, which promote interfacial charge transfer (IFCT) as a rapidly electron bridge. In particular, the photocatalytic hydrogen evolution rate of CuZnS NBs under visible light is 2.06 mmol·g−1·h−1, which is 5.9 times higher than that of Cu2-xS. The synthetic mechanism and photocatalytic mechanism of the CuZnS was investigated from experiment and theoretical calculations. The surface vacancy powered reverse cation exchange strategy offers a new opportunity for the rational tailoring new-generation photocatalysts at the atomic scale.

Acid etching-induced nanocutting of LaNiO3 transplanting self-assembled photodiode array-like LaNiO3/N,P-RGO nanoreactor for efficient photocatalytic hydrogen evolution

Nanoscale graphene-semiconductor composite photocatalysts with fascinating properties in the photocatalytic hydrogen evolution have inspired numerous interests in broad research fields. The architectures with efficient light response and promoting charge separation at the interface between reduced graphene oxide (RGO) and semiconductor are critical, yet synthesizing them remains a formidable challenge. Herein, the photodiode array-like LaNiO3/N,P-RGO (LNO/N,P-RGO) nanoreactor was constructed using an innovative strategy of acid etching-induced nanocutting self-assembly. Ammonium dihydrogen phosphate working as both a nitrogen phosphorus co-dopant and an acid etching reagent, cuts perovskite LaNiO3 (LNO) nanoparticles into nanorods, which are bonded evenly on the nitrogen phosphorus co-doped reduced graphene oxide (N,P-RGO) to form an n-n semiconductor heterojunction LNO/N,P-RGO as a photodiode array-like nanoreactor via hydrothermal treatment. The photodiode array-like nanostructure exposes more active sites that are conducive to light absorption. The robust Ni-C and P-O bonds promote the narrowing of space-charge region at the interface by UV irradiation, thereby improving the transport of photogenerated carriers by visible light irradiation. The LNO/N,P-RGO nanoreactor exhibits excellent photocatalytic hydrogen evolution performance with a yield of up to 354 μmol g−1 h−1 under UV–visible light, which is 50 times higher than that of pure perovskite LNO, and it also displays favorable recycling stability.

Active Sites Formed on InVO4/Co3O4 S‐Scheme Heterostructure for Photocatalytic Hydrogen Production

AbstractThe reasonable design of S‐scheme heterojunction to avoid unwanted charge transfer paths in hybrid semiconductors is considered to be an attractive method to obtain efficient photocatalytic hydrogen evolution activity. The photocatalytic hydrogen evolution performance of the system was improved by loading ultra‐thin InVO4 nanosheets on the surface of hollow cube Co3O4 to form an S‐scheme heterojunction. Benefiting from the unique nano‐cage structure derived from the zeolitic imidazolate frameworks (ZIF) series, it not only provides a good carrier for activating and stabilizing InVO4 nanosheets but also effectively avoids the masking of active sites caused by self‐agglomeration, which is more conducive to the exposure of more active sites. In the presence of sensitizer and sacrificial reagent, the optimized InVO4/Co3O4 has a more competitive H2 production, which is undoubtedly due to the construction of S‐scheme heterojunctions and unique spatial structure that facilitates the spatial separation of photoexcited charges. It is further confirmed that the photogenerated carrier transfer follows the S‐scheme mechanism by in‐situ irradiation XPS test.

Acceleration of the electron transfer for efficient photocatalytic hydrogen evolution via regulating the surfactant around the active center in 2D MOFs

Although surfactants have been proved to be effective in controlling the size and morphology to prepare high-quality two-dimensional (2D) MOF nanosheets, the impact of surfactants remaining on the 2D MOF nanosheets on their microenvironment is rarely reported. In this paper, polyvinylpyrrolidone (PVP) was used as surfactant to synthesize Co-TCPP(Pd) (abbreviated as Co-Pd) nanosheets, and the content of PVP attached to Co-Pd nanosheets was controlled by ethanol treatment, to regulate the microenvironment around Co-Pd nanosheets. The XRD, FT-IR, XPS, TEM, and TG were used to confirm that after ethanol ultrasonic treatment, the PVP content on Co-Pd nanosheets was gradually reduced without damaging the original structure and morphology of Co-Pd nanosheets. PVP attached to Co-Pd nanosheets will slow down the electron migration rate, affecting the microenvironment around co-catalyst Pd, which has been confirmed by EIS, PL and DFT etc. The results exhibited that the Co-Pd-6 obtained by ethanol ultrasonic treatment 6 times showed the more excellent photocatalytic hydrogen evolution activity (8284.25 umol·g−1·h−1), which was 4.02 times as that of Co-Pd-0 (2059.59 umol·g−1·h−1) without ethanol ultrasonic treatment), indicating that PVP will have a negative impact on the microenvironment around the co-catalyst, thereby affecting the photocatalytic hydrogen evolution performance. This study indicates that efficient photocatalytic hydrogen evolution can be achieved via adjusting the microenvironment around the co-catalyst to promote electron transfer.