Hydrogen Production Rate Research Articles

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.

Broad Light Absorption and Multichannel Charge Transfer Mediated by Topological Surface State in CdS/ZnS/Bi2Se3 Nanotubes for Improved Photocatalytic Hydrogen Production

AbstractSemiconductor heterojunctions have garnered extensive interest in photocatalytic hydrogen generation, yet the limited light absorption and charge transfer efficiencies still restrict the photocatalytic performance. The topological insulator has unique surface states and high‐mobility electrons, demonstrating the significant potential for enhancing photocatalysis. Herein, a ternary photocatalyst based on a topological insulator, in which CdS and ZnS nanoparticles are grown on Bi2Se3 nanotube, is prepared for efficient photocatalysis driven by topological surface state for the first time. Under simulated solar light irradiation, the CdS/ZnS/Bi2Se3 nanotubes display a robust photocatalytic hydrogen production rate of 7.13 mmol h−1 g−1, which is 69.2 times of CdS and comparable to many CdS‐based photocatalysts. The unique hollow structure, topological surface state of Bi2Se3, and cooperative bandgap excitations of the three components endow the hybrids with wide light response to harvest solar energy. Meanwhile, the multichannel charge transfer facilitated by topological surface state and internal electric fields within the hybrids effectively suppresses the recombination of the photogenerated charge carriers. This mechanism maintains a high concentration of stable electrons on Bi2Se3, resulting in highly efficient hydrogen production. This work provides a new inspiration for designing heterojunction photocatalysts based on topological insulators for high‐efficiency solar‐driven energy conversion.

The Influence of Catalyst Loading on Electrocatalytic Activity and Hydrogen Production in PEM Water Electrolysis

The climate change caused by the widespread and continuous use of fossil fuels is a problem that needs to be addressed urgently. One of the solutions offered is through an energy transition towards the use of new or renewable and low-carbon fuels. Hydrogen gas as a carrier of energy is an alternative solution that has attracted the attention of researchers, due to its high combustion energy and environmental friendliness. The production of hydrogen gas using the Proton Exchange Membrane Water Electrolysis (PEMWE) method is considered effective for large-scale production. This study investigates the impact of catalyst loading and various current densities on hydrogen production in the PEM water electrolysis process, utilizing the Cu2O/C catalyst. This study investigates the impact of catalyst loading and different current densities on hydrogen production in the PEM water electrolysis process, utilizing the Cu2O/C catalyst. The electrode catalytic properties were evaluated using the Cyclic Voltammetry (CV) method to determine the Electrochemical Surface Area (ECSA) and the Electrochemical Impedance Spectroscopy (EIS) method to determine the electrical conductivity. The ECSA and EIS measurements demonstrated that the best results were obtained at a higher catalyst loading of 2 mg/cm2 with an ECSA value of 0.21 m2/g and electrical conductivity of 3.04 × 10−6 S/cm. The production of hydrogen results showed that the highest hydrogen production rate was 3.75 mL/s with a catalyst loading of 2.5 mg/cm2, indicating that increasing the load could lead to a higher rate of hydrogen gas production, but this is highly dependent on the surface area utilized. Additionally, at higher current densities, the cell resistance in the electrolysis process may decrease, leading to reduced electrode efficiency for hydrogen production. Thus, the use of high currents may not always be advantageous in hydrogen production using the PEM water electrolysis method.

Ni-NCDs promoted photocatalytic benzylamine oxidation coupled hydrogen production in Cu-In-Zn-S/WO3·H2O Z-scheme heterojunction

The construction of Z-scheme heterojunction is important for efficient photocatalytic organic oxidation coupled hydrogen production. However, current methods suffer from poor synergy of charge extraction and surface reactions. In this study, we combined Cu-In-Zn-S (CIZS) quantum dots with WO3·H2O (WO) nanosheets to form a Z-scheme heterojunction, which was further modified with bifunctional N-doped carbon dots (NCDs) to improve charge extraction and abundant Ni sites for hydrogen evolution. The unique 0D/2D/0D CIZS/WO/Ni-NCDs heterojunction resulted in a hydrogen production rate of 4.261 mmol g−1 h−1, with ascorbic acid, 8.06 times higher than that of CIZS. In addition, the selectivity of N-benzylidenebenzylamine from benzylamine oxidation reaction has been increased from 31.65 % to 73.34 %. This improvement can be attributed to the efficient charge separation, transfer, and surface reactions accelerated by the multifunctional Ni-NCDs. A series of photoelectrochemical tests and radical scavenging experiments confirmed the Z-scheme photocatalytic process and the important roles of superoxide radicals and holes. Photo-induced electrocatalysis tests further confirmed the accelerated hydrogen evolution reaction in the presence of Ni-NCDs. Furthermore, time-resolved photoluminescence test demonstrated that the synergies of NCDs and Ni significantly extended the charge carrier lifetime. These findings provide valuable insights into efficient hydrogen production through the modulation of Z-scheme heterojunctions using bifunctional metal-carbon dots.

Fabrication of ZnO-carbon dots composite via microcrystalline cellulose for enhanced photocatalytic hydrogen production under simulated sunlight irradiation

The composite ZnO@CDs was prepared via the hydrothermal method. Microcrystalline cellulose (MCC) was used as the source of carbon dots (CDs). X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy, and transmission electron microscopy analyses were used to characterize the structure and morphology of ZnO@CDs. The prepared ZnO showed a flake morphology with the exposed plane of (001). The X-ray photoelectron spectroscopy and photoluminescence spectroscopy (PL) characterization showed that CDs can be produced by decomposition of MCC and then attached on the surface of ZnO. The photocatalytic properties of ZnO@CDs were investigated under simulated sunlight irradiation. The hydrogen production reached 1240 µmol·g-1 in 30 min, which was much higher than the bare ZnO. The mechanism for the enhanced catalytic property of ZnO@CDs was studied. A high hydrogen production rate (2480 µmol·g-1·h-1) in the short term would enable ZnO@CDs to work as an emergency power supply by hydrogen production and use for restoring electricity and wireless communication in complicated situations.

Microwave plasma-assisted hydrogen production via conversion of CO2–CH4 mixture

A method concerning re-use of the main greenhouse gases: CO2 and CH4 at the same time producing value-added chemicals (H2 + CO) is presented in this paper. The method involves the methane dry reforming using an atmospheric pressure operated 915 MHz microwave plasma source with a swirl gas flow. The effect of the CO2 to CH4 flow rates ratio, the total gas flow rate and the absorbed microwave power on the volume concentration of the gaseous plasma component in the outlet gas (%), CO2 and CH4 conversion rate (%), hydrogen production rate (g h−1) and energy yield of hydrogen production (g kWh−1) was investigated experimentally. The recorded results of the CO2 and CH4 conversion rate were about 82% and 88%, respectively. The best results in terms of the hydrogen production rate and energy yield of hydrogen production were equal to 156 g h−1 and 24 g kWh−1, respectively.

Construction of an interface interaction in a g-C3N4/CdS/NiS for photoreforming of plastic and clean hydrogen regeneration

Converting plastics into organic matter by photoreforming is an emerging way to deal with plastic pollution and produce valuable organic matter. Water shortage can be alleviated by using seawater resources. To solve these problems, we synthesize a ternary heterostructure composite g-C3N4/CdS/NiS. Heterojunctions are formed between graphitized carbon nitride (g-C3N4), cadmium sulfide (CdS) and nickel sulfide (NiS), which effectively improve the problem of fast charge recombination of pure g-C3N4 and CdS. The results of the g-C3N4/CdS/NiS photocatalytic tests show that the hydrogen production rates in seawater and pure water for 5 h are 30.44 and 25.79 mmol/g/h, respectively. In stability test, the hydrogen production rate of the g-C3N4/CdS/NiS in seawater and pure water is similar. This suggests that seawater can replace pure water as a source of hydrogen. While H2 is generated, the lactate obtained by polylactic acid (PLA) hydrolysis is oxidized to form small organic compounds such as formate, acetate and pyruvate. Our study shows that g-C3N4/CdS/NiS can not only use seawater as a hydrogen source to produce H2, but also photoreformate plastics dissolved in seawater into valuable small organic molecules. This has a positive impact on the production and use of clean energy, as well as on plastic pollution and water scarcity.

Efficient Photoelectrocatalytic glycerol to dihydroxyacetone synergistic hydrogen production on Co-LDH nanowires modified TiO2 nanorod arrays

The highly selective conversion of glycerol into high value-added products, accompanied by hydrogen generation, through photoelectrocatalytic technology represents an upcycling process that enhances resource utilization and sustainability. In this study, we designed a composite photoanode with a Type II heterojunction structure, Co-LDH(6 h)/TiO2, achieving a high glycerol conversion rate (1083.22 mmol·m−2·h−1) and hydrogen production rate (20.35 mmol·m−2·h−1) while maintaining a high level of DHA selectivity (48 %). Characterization revealed that the engineered Type II heterojunction significantly enhanced visible light absorption and charge separation, thereby reducing electron-hole recombination and improving the efficiency of glycerol conversion and hydrogen production. Furthermore, it was confirmed by in-situ Fourier transform infrared that the Co-LDH(6 h)/TiO2 composites exhibited significant affinity for adsorption intermediate hydroxyl group in glycerol and rapid desorption of DHA, which is a critical factor in achieving high selectivity for the oxidation pathway to DHA. Mechanistic analyses and isotopic labelling indicate that the photogenerated holes in the Co-LDH(6 h)/TiO2 photoanode are the primary active species responsible for the oxidation of glycerol, yielding a spectrum of valuable products. This research provides a novel strategy and in-depth understanding for developing efficient photoanodes for selective oxidation in organic reactions.

An innovative electrolytic cation exchange reactor system for cleaner generation of hydrogen gas using ocean water

The study presents a novel integrated three-compartment electrochemical continuous electrodeionization reactor that was constructed in a laboratory environment. In order to extract large amounts of carbon dioxide from naturally occurring oceanwater in the form of bicarbonate and carbonate, it develops a innovative electrolytic cation exchange process. At the same time, it produces hydrogen gas for possible hydrocarbon synthesis. The study employs the Box-Behnken experimental design approach implemented through the Design Expert software to investigate and optimize the performance of electrochemical hydrogen extraction from Ocean water from an integrated reactor. The integrated electrochemical continuous-type electrodeionization reactor comprises two cation-permeable membranes that operate as boundaries between three compartments: a central compartment and electrode compartments that house the cathode and anode, each of which may reverse polarity. These membranes are made of gel polystyrene cross-linked with divinylbenzene, which has acidic properties that allow cation transport while inhibiting anions. The integrated reactor's electrode chambers are enclosed in plexiglass end plates and contain distinct Plexiglass electrode compartments. These compartments have mesh and solid steel anode and cathode electrodes, with an electrode active area of 176.71 cm2. The influence of various factors, such as voltage and electrolyte amount, on the production of hydrogen synthesis is examined. The study results demonstrate a maximum hydrogen production rate of 2.2 mg/min and a hydrogen production efficiency of 7.82%. The lab testing was carried out using experimental equipment to determine viability. The tests included 35-min runs that measured hydrogen generation under various parameters, such as applied voltage, electrolyte concentration, and pH levels. The ocean salt solutions of 0.5M, 1M, and 2M were initially prepared and evaluated for hydrogen generation. Each concentration is assessed at a voltage range of 4–15V, with matching solution pH values ranging from 2 to 7. Optimization studies were conducted to enhance the hydrogen production rate. The results indicate that hydrogen production rises proportionally with applied voltage and electrolyte concentration but falls with pH growth. Within the Design Expert software, the statistical methods for response surface analysis and optimization are utilized accordingly.

Synthesis and characterization of black hydrogenated TiO2-rGO nanocomposites with enhanced photocatalytic activity

In this research, TiO2-GO composites were prepared by combination process included sol-gel for synthesizing TiO2 nanoparticles and afterward loaded GO on TiO2 (NPs) with hydrothermal treatment in ethanol/water medium. The black TiO2–H nanoparticles and TiO2-rGO-H nanocomposites were prepared through simple thermal hydrogen treatment at 600 °C for 3 h. The synthesized nanoparticles and the composite catalysts were characterized by XRD, FESEM, FTIR analyzes and the BET (Brunauer–Emmett–Teller) surface area measurement. The results revealed that synthesized TiO2 nanopowder was almost anatase phase with high crystallinity when coupled with GO leads to a decrease in the size of the crystallites by creation of smaller TiO2 clusters in result of enhanced dispersion of TiO2 on GO sheets. However, adding up GO has slightly improved optical properties of the photocatalyst samples. Compared with TiO2-GO composites, the high temperature (600 °C) hydrogenation produced anatase/rutile black TiO2-rGO nanocomposites enhanced hydrogen production rate 9 orders of magnitude higher than those observed for TiO2 powders, reached values of more than 368 μ mol g− 1 h – 1. A significant reduction in the energy band gap of 2.72 eV (DRS results) and also decreasing the electron-hole recombination according to PL spectra results has been recorded for TiO2-rGO-H nanocomposite. In addition, the black TiO2 nanoparticles and TiO2-rGO nanocomposites possessed much more concentration of oxygen vacancies and carrier concentration according to Raman analysis.

Fabrication and improved photocatalytic performance of 2D/0D structured g-C3N4/WO3 composite materials

In this work, WO3 quantum dots grow in situ on the synthesized ultra-thin g-C3N4 nanosheets, ultimately forming a type of tightly bound 2D/0D Z-type heterojunctions. It was found that WO3 quantum dots were closely combined with g-C3N4 nanosheets through SEM and TEM measurements. XRD, IR, and XPS characterization proved a g-C3N4/WO3 heterojunction material was formed. The construction of g-C3N4/WO3 heterojunctions enhanced visible light absorption, improved carrier separation efficiency, and reduced charge transfer resistance. Photocatalytic hydrogen production tests showed that the hydrogen production rate of 20% g-C3N4/WO3 composite materials was 2.8 times that of the original g-C3N4, and the hydrogen production amount within 3 h was 3.7 times that of the original g-C3N4. Photocatalytic degradation of Rhodamine B and 4-chlorophenol under visible light irradiation showed that compared with g-C3N4, the photocatalytic degradation efficiency of 20% g-C3N4/WO3 composite materials was enhanced. The results reveal that the special structured g-C3N4/WO3 composite materials have excellent photocatalytic activity, which can not only efficiently produce hydrogen but also efficiently degrade organic pollutants, providing an important reference for solving energy crises and environmental problems.

Construction of g-C3N4/Ti3CN MXene Schottky heterojunctions for boosting photocatalytic hydrogen production

Converting solar energy into clean hydrogen (H2) fuel via photocatalytic hydrogen production technology is a promising strategy for sustainable social development. Graphitic carbon nitride (g-C3N4) has attracted much attention due to its unique visible light activity and excellent tunable atomic structure. However, bulk g-C3N4 suffers from challenges such as sluggish charge carrier dynamics and limited active catalytic sites, resulting in lower solar-to-hydrogen conversion efficiency. Herein, we prepare defective ultrathin g-C3N4 nanosheets and subsequently construct 2D g-C3N4/2D Ti3CN MXene heterojunction via electrostatic-driven assembly. The optimized composite CM-2 exhibits the highest hydrogen evolution rate of 7630.5 µmol g−1 h−1. The increase in the hydrogen production rate is attributed to the effective coupling of two materials to form Schottky heterojunctions, which may inhibit the recombination of electron-hole pairs. Additionally, this work explores the pathway of electron transfer in Schottky photocatalyst, and further unveils the synergy of defects and built-in electric field in accelerating photo-induced charge transport as well as enhancing the hydrogen-evolving activity, thereby providing valuable insights for the rational design of highly efficient photocatalytic materials.

Trifunctional phosphorus-doped cobalt molybdate catalyst in self-driven coupling systems for synchronized sulfur recovery and hydrogen evolution

This study introduces a self-driven system that effectively achieves synchronized sulfur recovery and hydrogen production using a Zn-air battery. The system ingeniously integrates the sulfur oxidation reaction (SOR) and the hydrogen evolution reaction (HER) into a single, efficient process. Central to this system is the trifunctional phosphorus-doped cobalt molybdate catalyst (P-CoMoO4/NF), which exhibits superior performance in both HER (ηj = 100 = 0.13 V) and SOR (ηj = 100 = 0.30 V) with remarkable stability (∼360 h), reaching 0.64 V at 100 mA cm−2 for simultaneous sulfur ion degradation and hydrogen production. Through density functional theory simulations and extensive characterizations, it has been shown that phosphorus doping in the cobalt molybdate catalyst facilitates electron redistribution, enhancing the catalyst's conductivity, generating more oxygen vacancies, and promoting improved mass and electron transfer. This modification also lowers the energy barrier for adsorbing reaction intermediates, thus increasing the hydrogen production rate and sulfur oxide conversion in this self-powered system. In summary, this research marks a substantial advancement in the development of trifunctional catalysts and proposes an eco-friendly, cost-effective strategy for integrated reaction systems, paving the way for sustainable energy solutions.

Lab-scale validation and parametric numerical investigation on hydrogen production in a porous media as a byproduct of in-situ combustion

A numerical 1D model was developed and validated using the measured data on a porous tube lab experiment for hydrogen generation as an in-situ combustion (ISC) byproduct, and a detailed parametric numerical study was performed. This work explores the impacts of various water injection parameters on the generation of hydrogen, the oil recovery factor (ORF), and carbon monoxide using a thorough parametric analysis. The methodology included simulating the injection of mutually enriched air and water into the combustion tube, focusing on parameters such as water temperature, quality, and flow rates. Key findings reveal that the oxygen ratio in the oxidizer substantially influences hydrogen production and ORF, with hydrogen generation increasing from 1.65 × 103 cm3 to 3.0 × 103 cm3, which is around 82 % when the oxygen percentage is raised from 50 % to 95 %. The results showed that employing wet combustion instead of dry combustion increased the hydrogen production rate by roughly four times. Variable water temperature has insignificant impacts on the hydrogen production rate and ORF. Increasing the steam quality has an opposed effect on the hydrogen generation rate. Additionally, escalating the injected water flow rate from 3000 cm³/day to 15000 cm³/day boosts hydrogen production from 10000 cm³ to 53400 cm³, respectively.

H3PMo12O40@ZIF-67-derived CoMoC/ZnIn2S4 Schottky heterojunction for enhanced photocatalytic hydrogen evolution

In this work, a novel CMC/ZIS Schottky heterojunction photocatalytic material was synthesized by solvothermal complexation of the H3PMo12O40@ZIF-67 derived precursors with ZnIn2S4. According to the experimental findings, the 5% CMC/ZIS composite photocatalytic material outperformed the pure ZIS catalyst in terms of photoelectric performance and visible light responsiveness. The 5% CMC/ZIS Schottky heterojunction catalyst presents a hydrogen production rate of 2232 μmol g−1 h−1, which is about five times that of the pure ZIS. The high photocatalytic activity of the 5% CMC/ZIS composite can be attributed to the narrowed band gap and the formation of a Schottky heterojunction. The composite exhibits enhanced visible light absorption capability and faster-photogenerated electron separation efficiency. The study highlights the advantages of the integration of MOF derivatives with ZnIn2S4 for the preparation of composite photocatalysts with improved hydrogen production activities.

TiO2/ZnIn2S4 solar absorber: A multi-functional material for enhanced water evaporation, dye degradation, Cr6+ reduction, and hydrogen evolution

The comprehensive utilization of solar energy is a crucial approach to addressing water and energy shortages. In this study, Ⅱ-Scheme heterojunction TiO2/ZnIn2S4 was successfully designed and synthesized, exhibiting excellent performance in photothermal conversion, effective photodegradation of RhB, photoreduction of Cr (VI) and photocatalytic hydrogen production. The constructed TiO2/ZnIn2S4 heterojunction demonstrated significantly improved photo-response capabilities compared to individual TiO2 and ZnIn2S4 components. Photothermal water evaporation rate of the optimized TiO2/ZnIn2S4 heterojunction was 1.275 kg m−2 h−1 and the photothermal water evaporation efficiency reached 79.0 %. In addition, the material has excellent effect on photocatalytic RhB degradation (4.355 × 10−2 min−1) and Cr6+ reduction (0.8623 × 10−2 min−1). Meanwhile, the hydrogen production rate of this material was 3.0 and 1.5 times higher than that of pure TiO2 and ZnIn2S4, respectively. The multifunctional TiO2/ZnIn2S4 composites hold significant potential for applications in wastewater treatment and addressing the energy crisis, offering promising prospects in achieving sustainable and efficient utilization of solar energy.

Insights into the function of metallic 1T phase tungsten disulfide as cocatalyst decorated zinc indium sulfide for enhanced photocatalytic hydrogen production activity

Improving the separation efficiency of carriers is an important part of enhancing photocatalytic activity. Herein, we successfully decorated metallic 1T phase tungsten disulfide (1T-WS2) on the surface of zinc indium sulfide (ZnIn2S4) and investigated the synergistic effect of 1T-WS2 on ZnIn2S4. The characterization results show that 1T-WS2 improves the light absorption capacity and utilization efficiency, increases the catalytic active site, improves the photogenerated charge separation efficiency, and optimizes the reduction potential of ZnIn2S4. Theoretical calculations show that compared with ZnIn2S4, 1T-WS2/ZnIn2S4 has a smaller adsorption Gibbs free energy of the intermediate state H*, which is conducive to the catalytic reaction. Under simulated solar irradiation, the hydrogen (H2) production rate of 1T-WS2/ZnIn2S4 with a loading of 12 wt% reaches 30.90 mmol h−1 g−1, which is 3.38 times higher than that of single ZnIn2S4 (9.13 mmol h−1 g−1). In addition, the apparent quantum efficiency of 1T-WS2/ZnIn2S4 with a loading of 12 wt% reaches 21.14 % under monochromatic light at a wavelength of λ = 370 nm. This work analyzes the light absorption and carrier separation to the catalytic site, and elucidates the mechanism for the enhancement of the photocatalytic hydrogen production performance.

Molecular Regioisomerism of Benzobisthiazole‐Based Conjugated Polymers Promotes Photocatalytic Hydrogen Production

AbstractPolymer semiconductors hold great promise for photocatalytic hydrogen production due to their diverse structures and functions. Nevertheless, their photocatalytic performances are usually compromised by rapid charge recombination. Herein, a molecular regioisomerism strategy of benzobisthiazole (BT)‐based conjugated polymers is proposed for manipulating their optoelectronic properties through varying the conjugation directions of BT units. Despite subtle structural differences, the 4,8‐subsituted sample LCP‐BT‐48 exhibits an remarkably improved charge separation capability and a sixfold increase in the photocatalytic hydrogen production rate in comparison with those of the 2,6‐subsituted counterpart. Theoretical analysis demonstrates that the superior optoelectronic property of LCP‐BT‐48 is attributed to its sp2 carbon‐conjugated skeletons and enhanced local polarization electric field between BT and neighboring π‐units. This work provides a new paradigm for regulating charge‐transfer dynamics in conjugated polymers for efficient photocatalysis.

Cadmium doping induced type-II to Z-scheme switching in CdSe/BiVO4 heterojunction for enhancing photocatalytic hydrogen production

Heterojunction type in composite photocatalysts determines their charge carrier transfer path, which is critical to the redox capacity of their charge carriers and needs careful modulation for their designed photocatalytic reactions. In this work, a transit from the type-II (BVO/CdSe) to Z-scheme (CdSe/BVO) in CdSe/BiVO4 heterojunction happened by changing the deposition sequence of CdSe and BiVO4 layers to introduce Cd-doping into the BiVO4 layer, which fundamentally changed their charge carrier separation and transfer behaviors as demonstrated by both experimental and calculation results. So, the charge carrier separation efficiency in CdSe got largely enhanced, more photogenerated electrons with high reduction potential were allowed to participate in the photocatalytic H2 production, and photogenerated hole accumulation in CdSe reduced. As a result, the CdSe/BVO photoelectrode demonstrated the best photocatalytic hydrogen production rate (2.59 μmol cm−2 h−1), which is about 136.3 and 5.9 times higher than that of BVO/CdSe and pure CdSe, and the stability under visible light irradiation is also greatly improved.

Synthesis of mixed-ligand two-dimensional zeolite imidazole framework (ZIF-L) via water-assisted strategy for enhanced photocatalytic hydrogen evolution

Metal organic frameworks (MOFs) are regarded as the promising potential photocatalytic materials because of its high specific surface area, regular morphology and highly adjustable structure. Herein, introducing different addition percentage of 1-vinylimidazole to two-dimensional zeolite imidazole framework (ZIF-L) with leaf-shaped morphology was successfully prepared via water-assisted strategy and applied in the photocatalytic hydrogen evolution experiments. The results indicate that VZ-12 shows the highest photocatalytic activity with hydrogen production rate of 162.7 μmol g−1 h−1, which is 3 times than that in VZ-0 (pure ZIF-L, 56.33 μmol g−1 h−1) under simulated sunlight. The enhanced performance is ascribed to the increased specific surface area observed via BET, narrow band gap (Eg) explored through UV–vis DRS and decreased recombination of photo-generated charge carriers measured by photoluminescence (PL). In a word, the effort of our study provides a new idea for developing and fabricating efficient hydrogen production photocatalyst via water splitting.