Photocatalytic Hydrogen Production Performance Research Articles

Constructing CdIn2S4/ZnS type-I band alignment heterojunctions by decorating CdIn2S4 on ZnS microspheres for efficient photocatalytic H2 evolution

In this study, a series of promising binary hybrid heterojunction CdIn2S4/ZnS (CIS/ZnS) were constructed via a facile hydrothermal method. Credible characterization methods including powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–vis diffuse reflectance spectra (DRS) were carried out to investigate the physicochemical properties the as-obtained photocatalysts. Photocatalytic water splitting for hydrogen evolution was performed to evaluate the photocatalytic activity of the photocatalyst. The results indicate that the light-harvesting ability could be markedly enhanced by decorating CdIn2S4 on ZnS microspheres. Compared with the pristine CdIn2S4 and ZnS, the hybrid photocatalysts present more efficient photocatalytic hydrogen production performance. Among composite photocatalysts, the 5% CIS/ZnS sample manifests the highest photocatalytic hydrogen production rate of 10.80 mmol g−1 h−1, which is 2.6 and 5.4 times higher than that of ZnS and CdIn2S4, respectively. Moreover, a type-I band alignment mechanism was prudently put forward to interpret the photocatalytic hydrogen generation activity. The boosted photocatalytic hydrogen evolution activities of CIS/ZnS can be attributed to the enhanced light-harvesting ability, efficient separation and transfer of the photo-induced charge carriers, and inhibition of electrons and holes recombination of binary hybrid CIS/ZnS photocatalysts.

Synergism of 1D CdS/2D Modified Ti3C2Tx MXene Heterojunctions for Boosted Photocatalytic Hydrogen Production

Rational design and controllable synthesis of visible-light-responsive photocatalysts that exhibit both good hydrogen-producing efficiency and stability in the water splitting reaction are undoubtedly a challenge. Here we report an integrated CdS nanorod/oxygen-terminated Ti3C2Tx MXene nanosheet heterojunction with a high catalytic hydrogen evolution reaction (HER) activity. By incorporating one-dimensional (1D) CdS nanorods onto annealed ultrathin two-dimensional (2D) MXene nanosheets, the mixed-dimensional 1D/2D heterojunction achieved a hydrogen-evolving rate of 8.87 mmol·g−1·h−1, much higher than that of bulk CdS and CdS/unmodified MXene hybrid catalysts. The enhanced HER activity and stability of the designed heterojunction catalyst are attributed to the presence of oxygen-containing terminal groups on the surface of thermally treated Ti3C2Tx MXene, extended light absorption spectra as well as the precisely constructed intimate Schottky contact, implying an accelerated interfacial charge transfer and efficient, long-term photocatalytic hydrogen production performance. The results demonstrate that oxygen-terminated 2D MXene can be well utilized as a functional platform for the development of novel heterojunction photocatalysts.

Facile Synthesis of P-Doped ZnIn2S4 with Enhanced Visible-Light-Driven Photocatalytic Hydrogen Production.

ZnIn2S4 (ZIS) is widely used in the field of photocatalytic hydrogen production due to its unique photoelectric properties. Nonetheless, the photocatalytic performance of ZIS usually faces problems of poor conductivity and rapid recombination of charge carriers. Heteroatom doping is often regarded as one of the effective strategies for improving the catalytic activity of photocatalysts. Herein, phosphorus (P)-doped ZIS was prepared by hydrothermal method, whose photocatalytic hydrogen production performance and energy band structure were fully studied. The band gap of P-doped ZIS is about 2.51 eV, which is slightly smaller than that of pure ZIS. Moreover, due to the upward shift of its energy band, the reduction ability of P-doped ZIS is enhanced, and P-doped ZIS also exhibits stronger catalytic activity than pure ZIS. The optimized P-doped ZIS exhibits a hydrogen production rate of 1566.6 μmol g-1 h-1, which is 3.8 times that of the pristine ZIS (411.1 μmol g-1 h-1). This work provides a broad platform for the design and synthesis of phosphorus-doped sulfide-based photocatalysts for hydrogen evolution.

Using the femtosecond technique to study charge transfer dynamics

Transient absorption spectroscopy was used to directly observe the exciton relaxation process of an S-scheme heterojunction. Rapid interfacial charge transfer leads to high photocatalytic hydrogen production and organic transformation performance.

Hollow Cd0.9In0.1Se/Cu2MoS4 nanocube S-scheme heterojunction towards high photocatalytic hydrogen production

The solar-driven hydrogen production from water splitting using the composite photocatalyst is a potentially efficient strategy to achieve a stable supply of renewable hydrogen energy. Herein, hollow Cd0.9In0.1Se/Cu2MoS4 nanocubes were prepared through hydrothermal and thermal deposition methods. And the optimized Cd0.9In0.1Se/Cu2MoS4 photocatalyst displayed a high hydrogen production rate of 6358.42 μmol g−1 h−1 and great long-term recyclability. The hollow structure of Cu2MoS4 efficiently improved the utilization ratio of visible light. When Cd0.9In0.1Se nanoparticles was modified on the surface of hollow Cu2MoS4 nanocubes, the S-scheme heterojunction was formed and the built-in electric field at the interface was produced. It effectively facilitated the charge separation and transfer and reduced the recombination of photo-generated electrons and holes, thus enhancing the photocatalytic hydrogen production activity. This work provides a new insight for improving photocatalytic hydrogen production performance from the point of view of the hollow structure composite photocatalyst.

Preparation and Photocatalytic Performance of MoS2/MoO2 Composite Catalyst.

Solar energy is an inexhaustible clean energy providing a key solution to the dual challenges of energy and environmental crises. Graphite-like layered molybdenum disulfide (MoS2) is a promising photocatalytic material with three different crystal structures, 1T, 2H and 3R, each with distinct photoelectric properties. In this paper, 1T-MoS2 and 2H-MoS2, which are widely used in photocatalytic hydrogen evolution, were combined with MoO2 to form composite catalysts using a bottom-up one-step hydrothermal method. The microstructure and morphology of the composite catalysts were studied by XRD, SEM, BET, XPS and EIS. The prepared catalysts were used in the photocatalytic hydrogen evolution of formic acid. The results show that MoS2/MoO2 composite catalysts have an excellent catalytic effect on hydrogen evolution from formic acid. By analyzing the photocatalytic hydrogen production performance of composite catalysts, it suggests that the properties of MoS2 composite catalysts with different polymorphs are distinct, and different content of MoO2 also bring differences. Among the composite catalysts, 2H-MoS2/MoO2 composite catalysts with 48% MoO2 content show the best performance. The hydrogen yield is 960 µmol/h, which is 1.2 times pure 2H-MoS2 and two times pure MoO2. The hydrogen selectivity reaches 75%, which is 22% times higher than that of pure 2H-MoS2 and 30% higher than that of MoO2. The excellent performance of the 2H-MoS2/MoO2 composite catalyst is mainly due to the formation of the heterogeneous structure between MoS2 and MoO2, which improves the migration of photogenerated carriers and reduces the possibilities of recombination through the internal electric field. MoS2/MoO2 composite catalyst provides a cheap and efficient solution for photocatalytic hydrogen production from formic acid.

Photocatalytic hydrogen production of copolymers containing diiron model compounds in the presence of benzonitrile dye

In this paper, a kind of azapropylene [FeFe]-hydrogenases model (1) containing styrene structure was synthesized by classical ammonia condensation reaction. Then, a series of new metallopolymers (2a/2b/2c) were synthesized by copolymerization of styrene group and 2-(Dimethylamino)ethyl methacrylate (DMAEMA) with different proportions. The precursor (1) and metallopolymers (2a/2b/2c) were characterized by NMR, GPC, XPS, FT-IR, ICP-MS and TG-DTA, and the contents of metal model substance in the metallopolymers (2a/2b/2c) were accurately determined. Subsequently, the photocatalytic hydrogen production performance of the catalysts were studied. The photocatalytic system consists of photosensitizer (2,4,5,6-Tetrakis (diphenylamino)-isophthalonitrile), solvent (DMF/H2O) and electron donor (NEt3). Under the optimized conditions, the maximum hydrogen production of the catalytic system can reach 0.704 mmol (1, 0.34 mg) and 0.812 mmol (2a, 10 mg) within 1 h. The catalysts still have certain catalytic activity after 30 h of photocatalytic reaction. During a catalytic time of up to 30 h, 2c had the highest TON, with a value of 24530. In addition, the effect of the polymerization ratio of precursor 1 to DMAEMA monomer in the metallopolymers (2a/2b/2c) on the catalytic efficiency was also studied.

Pt quantum dots-coupled AgVO3/g-C3N4 Z-scheme photocatalyst for efficient sunlight-driven hydrogen production

Hydrogen production is regarded as an ideal approach to settle the worldwide energy and environmental issues. Here, a plasmonic Pt quantum dots (QDs) coupled Z-scheme 1D/0D/2D AgVO3/Pt/CN heterojunction (AvPtCN) was prepared in this work, indicating remarkable solar-light-driven photocatalytic activity. The obtained composites were characterized using a variety of structural spectroscopic methods, displaying a porous surface with more reactive sites, and improved visible-light harvesting, favorable for hydrogen production. Meaningfully, the ternary composite of AvPtCN demonstrated a significantly higher photogenerated charge separation efficiency and a substantially lower onset potential for hydrogen production. Moreover, the plasmonic Pt quantum dots could provide additional electron transfer routes between two component-photocatalysts, leading to improved carrier separation efficiency and enhanced lifetime of photoinduced charges, in comparison with the pristine CN and AgVO3, along with binary PtCN and AvCN composite. Consequently, the AvPtCN heterojunction exhibited much enhanced photocatalytic hydrogen production performance, up to 10,444 μmol/g/h. This work would be precious in developing novel Z-scheme photocatalysts and significant in meeting environmental needs.

The in-situ construction of 2D electronic channel for C/TiO2 via Ti3C2 and its H2-production performance

The extending of electronic transmission channel is very beneficial to accelerating the electronic transmission efficiency. Herein, the two-dimensional C/TiO2 composites with an extended electron transmission space were constructed by boric acid-induced hydrothermal method with Ti3C2 as template. The electron microscope shows that the C layer in C/TiO2 retains the original layered structure of Ti3C2. Heterogeneous interface formed between the titanium dioxide particles and the C layer, which is confirmed by HRTEM and XRD. The EPR proves that massive oxygen vacancies formed on the appearance of the heterogeneous. The results of PL spectrum, EIS and I-t transient photocurrent show that the C layer acted as electron transport path to improve the transmission efficiency of electrons. The cooperative effect of the conductive layer (C layer) and the electron trap (oxygen vacancy) accelerated the migration of photo-generated electrons, boosting an enhanced photocatalytic hydrogen production performance with about 3622.7 ( ± 108.2) μmol·g−1·h−1 on the BCT sample. As a result, the designed structure showed an enhanced photocatalytic hydrogen production performance with about 3622.7 ( ± 108.2) μmol·g−1·h−1 on the BCT sample compared with 0 μmol g−1 h−1 on the Ti3C2 sample. The BCT sample displayed a stable photocatalytic performance during the experimental process. It is wish that this research can supply a valuable idea for the application of the two-dimensional substances in photocatalysis.

Transition-Metal Single Atom Anchored on MoS2 for Enhancing Photocatalytic Hydrogen Production of g-C3N4 Photocatalysts.

Single-atom catalyst technology with near-100% atomic utilization and a well-defined coordination structure has provided new ideas for designing high-performance photocatalysts, which is also beneficial for reducing the usage of noble metal cocatalysts. Herein, a series of single-atomic MoS2-based cocatalysts where monoatomic Ru, Co, or Ni modify MoS2 (SA-MoS2) for enhancing the photocatalytic hydrogen production performance of g-C3N4 nanosheets (NSs) are rationally designed and synthesized. The 2D SA-MoS2/g-C3N4 photocatalysts with Ru, Co, or Ni single atoms show similar enhanced photocatalytic activity, and the optimized Ru1-MoS2/g-C3N4 photocatalyst has the highest hydrogen production rate of 11115 μmol/h/g, which is about 37 and 5 times higher than that of pure g-C3N4 and MoS2/g-C3N4 photocatalysts, respectively. Experimental and density functional theory calculation results reveal that the enhanced photocatalytic performance is mainly attributed to the synergistic effect and intimate interface between SA-MoS2 with well-defined coordination single-atomic structures and g-C3N4 NSs, which is conducive to the rapid interfacial charge transport, and the unique single-atomic structure of SA-MoS2 with modified electronic structure and appropriate hydrogen adsorption performance offers abundant reactive sites for enhancing the photocatalytic hydrogen production performance. This work provides new insight into improving the cocatalytic hydrogen production performance of MoS2 by a single-atomic strategy.

Metal-Free 2D/2D van der Waals Heterojunction Based on Covalent Organic Frameworks for Highly Efficient Solar Energy Catalysis

HighlightsIt is the first attempt to combine covalent organic frameworks with hexagonal boron nitride (h-BN) to construct efficient metal-free photocatalyst.The composite displays superior photocatalytic hydrogen production performance in metal-free systems.The integrated porous h-BN can suppress electron backflow to optimize the composite photocatalytic activity.

Synthesis of copper-doped indium zinc sulfide nanosheets for high efficiency photocatalytic hydrogen production

The excessive use of fossil energy has caused a series of environmental problems. Hydrogen is a green energy substitute for fossil energy, and photocatalytic hydrogen production is an effective means of hydrogen production. Indium zinc sulfide catalyst has great application prospect in the field of photocatalysis due to its advantages of high stability and visible light absorption. Based on this, Cu doped indium zinc sulfide nanosheets were prepared in this paper. Compared with pure indium zinc sulfide nanosheets, copper doped indium zinc sulfide nanosheets have better photocatalytic hydrogen production performance. The design and synthesis of photocatalytic hydrogen-producing catalyst has important guiding significance.

Boosting photocatalytic hydrogen production based on amino acid derived Zn-MOF/CdS composite photocatalysts

The utilization of solar energy to decompose water and produce hydrogen is one of the important strategies to solve the problems of ecological environment and energy crisis. Herein, a series of CdS-modified Metal-Organic Frameworks (MOFs) composites Zn(LFor)-MOF/CdS were successfully prepared through the reaction of N-(4-pyridine-methyl)-l-valine·HCOONa (NaLFor), Zn acetates, and CdS nanoparticles. The composite Zn(LFor)-MOF/CdS exhibit a very high photocatalytic performance for hydrogen production from water cracking under visible light irradiation, which is superior to the pristine MOF and cadmium sulfide materials. The hydrogen production based on different proportions of Zn(LFor)-MOF/CdS materials were investigated, and the prepared Zn(LFor)-MOF/CdS (4:1) material showed excellent hydrogen evolution performance with the hydrogen yield reaching 267.6 μmol/h. Zn(LFor)-MOF/CdS (4:1) has a high photocurrent intensity, which can effectively inhibit the photoelectron-hole recombination, improve the electron-hole transport ability at the interface, accelerate the electron migration, which makes this material a high hydrogen production photocatalytic activity.

Novel interfacial lateral electron migration pathway formed by constructing metallized CoP2/CdS interface for excellent photocatalytic hydrogen production

Promoting photo-induced electron transfer is one of the most efficient approaches for improving photocatalytic hydrogen production performance. Herein, we construct a novel interfacial lateral electron migration path by introducing CoP2 into CdS photocatalytic system as cocatalyst for the first time. This peculiar migration path can be attributed to two aspects: 1) the built-in electric field between CoP2 and CdS could drive carrier separation effectively; 2) the “metallized” interface serves as a special electron trap to accumulate electrons and promote them transfer along it instead of diffusion into cocatalyst. The energy-efficient interface shortens the electron migration distance and make more hot electrons participate in the reaction at the active sites with lower activation energy. As expected, the optimal hydrogen production rate of CoP2/CdS reaches up to 1071 mmol h−1 g−1, which is one of the most robust photocatalytic hydrogen production systems.

Construction of ZnIn2S4/Bi2MoO6 heterojunction enhancement photocatalytic hydrogen evolution performance under visible light

One of the major challenges in photocatalytic hydrogen production is to improve the separation efficiency of photo-generated carriers. Therefore, we prepared ZIS/BMO heterojunctions by hydrothermal method to promote the directional separation of photogenerated carriers. A series of characterization results show that the successful preparation of heterojunctions substantially increases the separation and transfer rate of photogenerated carriers. 11% ZIS/BMO had the highest photocatalytic hydrogen production performance reached 1502.6 μmol/g/h, which is 2.78 times than ZIS monomer. Simple construction of heterojunctions but dramatic improvement of photocatalytic hydrogen production performance opens up new horizons for photocatalyst modification.

Nitrogen doping mediated oxygen vacancy and Ti valence regulation to enhance photocatalytic H2 generation

The band gap width has always been the main reason for the low photocatalytic performance of TiO2 semiconductors. “Band gap engineering” is often used to change the band gap width of TiO2. On this basis, the impurity band gap was induced below the TiO2 conduction band by regulating N element. What's interesting was that N element adjusted the valence state of adjacent Ti element and caused the generation of oxygen vacancy. This is due to the extraction of neutral oxygen atoms, resulting in electron transfer to the Ti cation band structure. The 300-N-T catalyst exhibited the best photocatalytic hydrogen production performance under visible light, which was 307.65 μmol/(g·h) and was 61.53 times higher than that of anatase. And the concentration of Ti3+ defects and oxygen vacancy reduced with decreasing of N content in TiO2. According to Kubelke Munk formula, the band gap of 300-N-T photocatalyst was narrowed to 2.73 eV, which indicated that there are impurity energy levels near the CB and VB of TiO2 material. The Ti3+ ions as the active site of the photocatalytic reaction was confirmed by instantaneous photocurrent response and EIS characteristic. This study revealed the structure-activity relationship between the content of N element, Ti3+ ions and oxygen vacancy in TiO2 materials, as well as the decisive process of defect induced visible light catalysis.

Growing one-dimensional Cd0.9Zn0.1S nanorods on two-dimensional Ti3C2 MXene nanosheets for superior photocatalytic hydrogen production performance

Ti3C2 MXene as a high electrical conductivity with a large surface area, is widely used as a co-catalyst. In this work, 1D Cd0.9Zn0.1S nanorods (NRs) are grown on the surface of 2D Ti3C2 MXene nanosheets (NSs) to construct 1D/2D Cd0.9Zn0.1S/Ti3C2 nanocomposites, which reduce the stacking of Ti3C2 MXene and increase the layer spacing. Cd0.9Zn0.1S/Ti3C2 nanocomposite with 5 wt% Ti3C2 MXene adding amount achieves the hydrogen production rate of 4.50 mmol·h−1·g−1, which is 1.7 times than that of pure Cd0.9Zn0.1S (2.65 mmol·h−1·g−1). The remarkable enhancement of its photocatalytic activity is mostly attributed to three factors. Firstly, the electron-hole separation and charge transfer on the heterojunction between 1D Cd0.9Zn0.1S NRs and Ti3C2 MXene. Secondly, the 1D Cd0.9Zn0.1S nanorod structure can shorten the carrier transfer distance. Thirdly, the good electrical conductivity and large surface area of Ti3C2 MXene nanosheets are advantageous to the separation and transfer of photogenerated electron-hole pairs and increase the reaction sites.

Lanthanum modified Ni2P/CdS ohmic contact for significantly enhanced photocatalytic hydrogen production performance

Lanthanum modified Ni2P/CdS ohmic contact for significantly enhanced photocatalytic hydrogen production performance

One-pot fabrication CoS2 modified MoS2-g-C3N4 ternary heterostructure composites with enhanced photocatalytic hydrogen production from water

In this work, we prepared several CoS2-MoS2-g-C3N4 ternary heterojunction photocatalysts in-situ synthesized at one-pot high temperature processing. The spectroscopic and optoelectronic properties of the samples were analyzed by fluorescence and electrochemical methods, while the photocatalytic hydrogen production activity and stability of the different samples were investigated under visible light conditions (λ ≥ 420 nm). The results showed that the 0.02-CoS2-MoS2-g-C3N4 sample exhibited excellent photocatalytic production performance. It's because of the improved separation and transport capacity of photogenerated electrons and holes, which based on the effect of heterojunction between MoS2 and g-C3N4. The introduction of CoS2 could be further enhance the photocatalytic hydrogen production performance due to the increased active center and reducing the reaction energy barrier. This study can provide a new insight in the practical applications for photocatalytic hydrogen production.

Highly efficient visible-light photocatalytic hydrogen production using ZIF-derived Co9S8/N, S-CNTs-ZnIn2S4 composite

A hierarchical Co9S8/N, S-CNTs-ZnIn2S4 (CSCNs-ZIS) composite was reasonably constructed by grafting ZnIn2S4 nanosheets on the ZIF (67) derived Co9S8/N, S-doped carbon nanotubes for effective photocatalytic hydrogen production. The aggregated ZnIn2S4 nanosheets were uniformly wrapped on the surface of CSCNs, forming a hierarchical core–shell configuration, which effective inhibition of charge-carrier recombination. The CSCNs was adopted as an effective multi-component co-catalyst and further promoted photocatalytic hydrogen production performance. The H2 production rate of optimized CSCNs-ZIS composite reached 2409.2 μmol·h−1·g−1 and has high stability after three cycles. This work may inspire the design of a new noble-metal-free multi-component co-catalyst for sustainable H2 production.