Maximum Hydrogen Evolution Rate Research Articles

Enhanced photocatalytic hydrogen evolution using dual templates of sulfur-doped carbon nitride

The band structure of semiconducting photocatalysts plays a crucial role in determining their charge carrier transport characteristics and photocatalytic activity. In this work, a simple method to modulate the band structures of carbon nitride by infusing dopants and porous materials is experimentally demonstrated. A combination of trithiocyanuric acid and ammonium chloride to calcinate in an air environment, sulfur dopants and a significant amount of porosity are infused into carbon nitride concurrently. The sulfur-doped and porous carbon nitride material shows remarkable performance in photocatalytic hydrogen production, achieving a maximum hydrogen evolution rate of 4516.84 μmol g−1 h−1. Furthermore, infusion of sulfur dopants and abundant porous into carbon nitride allows for substantial and continuous tuning of the conduction and valence band positions. The band structures modulation enhanced the optical absorption in visible light region, making it suitable for efficient solar energy conversion. The findings of this work are feasible to pave a foundation for future clean energy technology.

Regulating the Photoisomerization of Covalent Organic Framework for Enhanced Photocatalytic Hydrogen Evolution†

Comprehensive SummaryCovalent organic framework (COF) is a desirable platform to tailor electronic properties for improving photocatalytic performances. However, the study on excited‐state configurations that determine photogenerated carrier dynamics has long been neglected. Herein, we concentrate on the molecular design of β‐ketoenamine‐linked COFs to drive their photoisomerization via the excited‐state intra‐molecular proton transfer (ESIPT), which can induce the partial keto‐to‐enol tautomerization and accordingly rearrange the photoinduced charge distribution. We demonstrate that the push‐pull electronic effect of functional side groups attached on the framework linkers is directly correlated with the ESIPT process. The phenylene linkers modified with electron‐withdrawing cyano‐groups reinforce the ESIPT‐induced tautomerization, leading to the in situ partial enolization for extended π‐conjugation and rearranged electron‐hole distribution. In contrast, the electron‐rich linkers limit the photoisomerization of COF and suppress the photoinduced electron accumulation. Thus, the maximum hydrogen evolution rate is achieved by the cyano‐modified COF, reaching as high as 162.72 mmol·g–1·h–1 with an apparent quantum efficiency of 13.44% at 475 nm, which is almost 11.5‐fold higher than those of analogous COFs with electron‐rich linkers. Our work opens up an avenue to control over the excited‐state structure transformation for enhanced photochemical applications.

Efficient and stable dehydrogenation of methylcyclohexane over Pt supported on mesoporous alumina with excellent textural properties

Mesoporous alumina (MA) materials with outstanding textural properties have been synthesized by a facile approach, and were evaluated as supports of Pt-based catalyst for methylcyclohexane dehydrogenation. At 300 °C, the resultant catalyst demonstrates a much higher activity with a maximum hydrogen evolution rate of 2081 mmol/gPt/min in comparison with the state-of-the-art alumina supported Pt catalysts. Interestingly, even after a long-time reaction of 100 h or regeneration, more than 80% of original activity was still maintained. The superior catalytic performance of the obtained catalyst is associated with the high specific surface area and large mesoporous size of support MA, thus benefiting the increase in the number of Pt active sites and efficiently inhibiting the formation of coke deposition during the reaction. Our contribution has provided a rational design strategy for highly efficient and stable dehydrogenation catalysts, which is a key for the utilization of methylcyclohexane-toluene system in hydrogen storage technology.

A recyclable ZnIn2S4/PAN photocatalytic nanofiber membrane for boosting visible light hydrogen evolution in seawater without cocatalyst

Using seawater for photocatalytic hydrogen production is always a highly promising direction. However, traditional powdered photocatalysts encounter challenges like ion interference and difficulty in reuse. To address these issues, we have combined the photocatalyst ZnIn2S4 (ZIS) with a polymer (PAN) using electrospinning technology to produce a composite photocatalytic ZIS/PAN nanofiber membrane. In aqueous solution, the ZIS/PAN nanofiber membrane achieves a maximum hydrogen evolution rate of approximately 1836 μmol/g/h, which is 3.37 times that of ZIS particles. Additionally, cyanide groups on PAN fibers can capture a small portion of photogenerated electrons, which then adsorb ions from seawater, reducing their impact on the photocatalyst and demonstrating excellent seawater hydrogen production performance. At specific ion concentrations, the membrane's activity is 20 % higher than in aqueous solution. Moreover, it overcomes the limitations of powdered photocatalyst structures, enabling device integration that facilitates easy recovery and reuse.

Metal(Cu)-graphdiyne modified anion doped Mn0.3Cd0.7S used for photocatalytic hydrogen production

The filling strategy of defect engineering and metal-semiconductor based co-catalysts are effective means to improve photo generated electron transfer and enhance photocatalytic performance. Herein, metal nano copper is used to catalyze the coupling of acetylene groups to form metal-graphdiyne, which is introduced into Mn0.3Cd0.7S with anionic filling vacancies. The maximum hydrogen evolution rate can reach 5063.69 umol·g−1. The initial guidance of photo generated electrons is achieved by filling them with heteroatoms. At the same time, the potential barrier formed between metals and semiconductors hinders the recombination of photo generated electrons and holes, once again playing a guiding role in photo generated electrons. Ultimately achieving the goal of improving photocatalytic activity.

In-situ growth 2D Fe2P nanosheets on the surface of 1D Cd0.9Zn0.1S nanorods for remarkably improved photocatalytic H2 evolution

Loading cocatalysts can effectively reduce the hydrogen production overpotential and provide additional catalytic sites. Fe2P, with abundant active sites, low hydrogen evolution overpotential, is regarded as a promising cocatalyst to replace the noble metals. Fe2P nanosheets were grown in situ on the surface of Cd0.9Zn0.1S nanorods to form unique 2D/1D structure, which was designed to enlarge the interface contact between them. The maximum hydrogen evolution rate was as high as 38.48 mmol h−1 g−1, which was even higher than that of noble metal Pt modified Cd0.9Zn0.1S. The results of characterization and theoretical computation demonstrated that the electronic interaction existed between Fe2P and Cd0.9Zn0.1S, and Fe2P as cocatalyst collected electrons to facilitate the transfer and separation of electrons and holes. This work investigated the transfer process of photogenerated carriers and revealed the photocatalytic mechanism through a combination of theoretical calculation and experimental characterization.

Nickel phosphide cocatalyst and carbon defects simultaneously boosting the photocatalytic hydrogen production over carbon nitride

The suppression of photogenerated carrier recombination in carbon nitride and the consequent enhancement of its photocatalytic hydrogen evolution performance have emerged as a research hotspot in the field of photocatalysis. Herein, Nickel phosphide (Ni2P) was anchored onto carbon nitride with carbon defects through a synthesis involving thermal polymerization and photoreduction. The existence of carbon defects derived from the rupture of carbon nitride (CN) heterocycles were beneficial to strengthening optical absorption and the separation capabilities of photogenerated carriers. Furthermore, Ni2P cocatalysts could serve as electron acceptors that effectively accelerate the transfer and transport capabilities of the photogenerated charge carriers. Consequently, the 7 wt% Ni2P/CNN photocatalyst achieved a maximum hydrogen evolution rate of 2062 μmol·g−1·h−1, which was 7.8 times and 6.2 times greater than that of Ni2P/CN and Ni/CNN, respectively, and was comparable to the rate achieved by 3 wt% Pt/CNN. This result was comparable or even better than those reported previously. Our work provided a simply strategy for developing non-precious metal-based nickel phosphide photocatalysts for renewable solar-driven photocatalytic hydrogen production.

Mesoporous TiO2 Single-Crystal Particles from Controlled Crystallization-Driven Mono-Micelle Assembly as an Efficient Photocatalyst.

Mesoporous materials with crystalline frameworks have been widely explored in many fields due to their unique structure and crystalline feature, but accurate manipulations over crystalline scaffolds, mainly composed of uncontrolled polymorphs, are still lacking. Herein, we explored a controlled crystallization-driven monomicelle assembly approach to construct a type of uniform mesoporous TiO2 particles with atomically aligned single-crystal frameworks. The resultant mesoporous TiO2 single-crystal particles possess an angular shape ∼80 nm in diameter, good mesoporosity (a high surface area of 112 m2 g-1 and a mean pore size at 8.3 nm), and highly oriented anatase frameworks. By adjusting the evaporation rate during assembly, such a facile solution-processed strategy further enables the regulation of the particle size and mesopore size without the destruction of the oriented crystallites. Such a combination of ordered mesoporosity and crystalline orientation provides both effective mass and charge transportation, leading to a significant increase in the hydrogen generation rate. A maximum hydrogen evolution rate of 12.5 mmol g-1 h-1 can be realized, along with great stability under solar light. Our study is envisaged to extend the possibility of mesoporous single crystal growth to a range of functional ceramics and semiconductors toward advanced applications.

Nitrogen and sulfur co-doped coal-based carbon quantum dots enhance the photocatalytic hydrogen evolution of Co-Fe-P derived from MOF

In order to explore the functional application of coal and realize the high-value application of low-quality coal. Therefore, low-cost coal as a carbon source into environmental protection, high-value coal-based carbon quantum dots (CQDs). This study employed high-sulfur coal as the carbon source and urea as the nitrogen source to successfully synthesize nitrogen and sulfur co-doped coal-based carbon quantum dots (NSCQDs) via a one-pot hydrothermal method. These NSCQDs were utilized as co-catalysts to assist the photocatalytic water splitting and hydrogen evolution of metal phosphides (Co-P and Fe-P). The obtained catalysts were subjected to systematic structural and property analyses, and the photocatalytic hydrogen evolution activity and stability were investigated, along with an analysis of the photocatalytic mechanism. The results revealed that the novel composite photocatalyst exhibited high hydrogen evolution activity, with a maximum hydrogen evolution rate of 28.41 mmol·g−1·h−1 at pH 10. Under a wavelength of 520 nm, the apparent quantum efficiency (AQE) reached 4.93%, and the solar-to-hydrogen (STH) conversion efficiency reached 0.46%. The semiconductor type (n-type) of the monophasic catalyst was determined through Mott-Schottky analysis, and the band structure was analyzed accordingly. The conduction and valence band positions for Co-P were determined to be -0.44 eV and 1.31 eV, respectively, while those for Fe-P were found to be -0.51 eV and 1.17 eV, respectively. Based on these results, it is inferred that an S-type heterojunction is formed between Co-P and Fe-P, and NSCQDs enhanced photocatalytic hydrogen evolution as an auxiliary catalyst. This research advances the synthesis of coal-based carbon quantum dots and provides the key information for the photocatalytic decomposition of water and hydrogen evolution using coal-based CQDs.

Synthesis and testing of NixZn1-xFe2O4/CNTs photoresponsive magnetic composite catalysts for hydrogen generation from water splitting

The world is facing environmental pollution and energy shortage challenges due to the enormous wastage of organic pollutants by industries and the rapid growth of the human population. Photocatalysis has been reported as an efficient technology to mitigate these two emerging issues. This study investigated heterojunction photocatalysts based on NixZn1-xFe2O4/CNTs for enhanced H2 production from water splitting. The role of CNTs in accepting electrons during redox reactions, improving the photocatalytic activity and stability of NiZnFe2O4, and reducing the recombination of charge carriers is also elaborated in this study. The synthesized NixZn1-xFe2O4/CNTs composites were characterized using several methods, including SEM, EDX, FTIR, XRD, and UV–Vis-DRS to examine their magnetic electrical, opto-physical, and photocatalytic activity. The maximum hydrogen evolution rate of 4550 μmolh−1g−1 was observed using N0.4Z0.6FC0.3, which is 5 and 2.3 times greater than that of NZF and Ni0.1Zn0.9FC0.3 catalysts, respectively. The successive cycles of hydrogen production using N0.4Z0.6FC0.3 showed strong stability and reusability of this catalyst. The photocatalytic mechanism of water splitting using NixZn1-xFe2O4/CNTs photocatalysts is also deduced in this study.

Understanding Structure-Activity Relationship in Pt-loaded g-C3 N4 for Efficient Solar- Photoreforming of Polyethylene Terephthalate Plastic and Hydrogen Production.

Coupling the hydrogen evolution reaction with plastic waste photoreforming provides a synergistic path for simultaneous production of green hydrogen and recycling of post-consumer products, two major enablers for establishment of a circular economy. Graphitic carbon nitride (g-C3 N4 ) is a promising photocatalyst due to its suitable optoelectronic and physicochemical properties, and inexpensive fabrication. Herein, a mechanistic investigation of the structure-activity relationship of g-C3 N4 for poly(ethylene terephthalate) (PET) photoreforming is reported by carefully controlling its fabrication from a subset of earth-abundant precursors, such as dicyandiamide, melamine, urea, and thiourea. These findings reveal that melamine-derived g-C3 N4 with 3wt.% Pt has significantly higher performance than alternative derivations, achieving a maximum hydrogen evolution rate of 7.33mmolH2 gcat -1 h-1 , and simultaneously photoconverting PET into valuable organic products including formate, glyoxal, and acetate, with excellent stability for over 30h of continuous production. This is attributed to the higher crystallinity and associated chemical resistance of melamine-derived g-C3 N4 , playing a major role in stabilization of its morphology and surface properties. These new insights on the role of precursors and structural properties in dictating the photoactivity of g-C3 N4 set the foundation for the further development of photocatalytic processes for combined green hydrogen production and plastic waste reforming.

Photocatalytic overall water splitting hydrogen production over ZnCdS by spatially-separated WP and Co3O4 cocatalysts

Loading suitable oxidation and reduction cocatalysts on sulfide semiconductor photocatalysts for H 2 and O 2 production reaction still remain a great challenge. Herein, we present a simple physical mixing strategy to load reduction cocatalyst WP and oxidation cocatalyst Co 3 O 4 co-modification ZnCdS (WP–Co/ZCS) with excellent photocatalytic water splitting activity. The co-modification of the double auxiliary catalysts can efficiently accelerate the separation of photocarriers, enhance the reaction kinetics and significantly advance the photocatalytic activity. The maximum hydrogen evolution rate of 21.44 mmol g -1 h -1 is attained over 10% WP-Co/ZCS photocatalyst, which is about 6.5 folds higher than bare ZnCdS, and a high photostability is also obtained. Meanwhile, a notable quantum efficiency of 27.6% at 420 nm and solar-hydrogen conversion efficiency (STH) of 1.57% are achieved, which is significantly surpassing many reported ZnCdS-based photocatalysts. Remarkably, an efficient and stable photocatalytic overall water splitting activity are achieved with hydrogen and oxygen generation rates of 61 μmol g -1 h -1 and 32.5 μmol g -1 h -1 for 10% WP-Co/ZCS, respectively. This work provides a new idea for designing oxidation and reduction dual-catalysts on ZnCdS nanoparticles to advance photocatalytic hydrogen generation performance and achieve pure water splitting. An efficient WP/Co 3 O 4 /ZnCdS dual cocatalysts photocatalytic system was constructed for overall water splitting. The highest photocatalytic H 2 production rate of 21.44 mmol g -1 h -1 is achieved over 10% WP-Co/ZnCdS with a high AQE of 27.6% at 420 nm. And the solar-hydrogen conversion efficiency (STH) is up to 1.57% for 10% WP-Co/ZnCdS. Remarkably, an efficient and stable photocatalytic overall water splitting activity are achieved with hydrogen and oxygen generation rates of 61 μmol g -1 h -1 and 32.5 μmol g -1 h -1 for 10% WP-Co/ZCS, respectively. • An efficient WP/Co 3 O 4 /ZnCdS dual cocatalysts photocatalytic system was constructed. • Photocatalytic H 2 production rate of 21.44 mmol g -1 h -1 is achieved over 10% WP-Co/ZnCdS with a high AQE of 27.6% at 420 nm. • The solar-hydrogen conversion efficiency (STH) is 1.57% for 10% WP-Co/ZnCdS. • Matching of HER/OER via WP and Co 3 O 4 can actualize the overall water splitting. • Photocatalytic overall water splitting for H 2 /O 2 generation rates are 61/32.5 μmol g -1 h -1 over 10% WP-Co/ZCS.

Constructing tightly integrated conductive metal-organic framework/covalent triazine framework heterostructure by coordination bonds for photocatalytic hydrogen evolution

The construction of tightly integrated heterostructures with metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) has been confirmed to be an effective way for improved hydrogen evolution. However, the reported tightly integrated MOF/COF hybrids were usually limited to the covalent connection of COFs with aldehyde groups and NH2-MOF via Schiff base reaction, restricting the development of MOF/COF hybrids. Herein, a covalent triazine framework (CTF-1), a subtype of crystalline COFs, was integrated with a conductive two-dimensional (2D) MOF (Ni-CAT-1) by a novel coordinating connection mode for significantly enhanced visible-light-driven hydrogen evolution. The terminal amidine groups in the CTF-1 layers offer dual N sites for the coordination of metal ions, which provides the potential of coordinating connection between CTF-1 and Ni-CAT-1. The conductive 2D Ni-CAT-1 in Ni-CAT-1/CTF-1 hybrids effectively facilitates the separation of photogenerated carriers of CTF-1 component, and the resultant hybrid materials show significantly enhanced photocatalytic hydrogen evolution activity. In particular, the Ni-CAT-1/CTF-1 (1:19) sample exhibits the maximum hydrogen evolution rate of 8.03 mmol g−1h−1, which is about four times higher than that of the parent CTF-1 (1.96 mmol g−1h−1). The enhanced photocatalytic activity of Ni-CAT-1/CTF-1 is mainly attributed to the incorporation of conductive MOF which leads to the formation of a Z-Scheme heterostructure, promoting the electron transfer in hybrid materials. The coordinating combination mode of Ni-CAT-1 and CTF-1 in this work provides a novel strategy for constructing tightly integrated MOF/COF hybrid materials.

Cu2O/CuS/ZnS Nanocomposite Boosts Blue LED-Light-Driven Photocatalytic Hydrogen Evolution

In the present work, we described the synthesis and characterization of the ternary Cu2O/CuS/ZnS nanocomposite using a facile two-step wet chemical method for blue LED-light-induced photocatalytic hydrogen production. The concentrations of the ZnS precursor and reaction time were essential in controlling the photocatalytic hydrogen production efficiency of the Cu2O/CuS/ZnS nanocomposite under blue LED light irradiation. The optimized Cu2O/CuS/ZnS nanocomposite exhibited a maximum photocatalytic hydrogen evolution rate of 1109 µmolh−1g−1, which was remarkably higher than Cu2O nanostructures. Through the cycle stability it can be observed that the hydrogen production rate of the Cu2O/CuS/ZnS nanocomposite decreased after 4 cycles (1 cycle = 3 h), but it remained at 82.2% of the initial performance under blue LED light irradiation. These reasons are mainly attributed to the introduction of CuS and ZnS to construct a rationally coupled reaction system, which enables the synergistic utilization of photogenerated carriers and the increased absorption of visible light for boosting blue LED-light-driven photocatalytic hydrogen evolution.

Binary Type-II Heterojunction K7HNb6O19/g-C3N4: An Effective Photocatalyst for Hydrogen Evolution without a Co-Catalyst.

The binary type-II heterojunction photocatalyst containing g-C3N4 and polyoxoniobate (PONb, K7HNb6O19) with excellent H2 production activity was synthesized by decorating via a facile hydrothermal method for the first time. The as-fabricated Nb–CN-0.4 composite displayed a maximum hydrogen evolution rate of 359.89 µmol g−1 h−1 without a co-catalyst under the irradiation of a 300 W Xenon Lamp, which is the highest among those of the binary PONb-based photocatalytic materials reported. The photophysical and photochemistry analyses indicated that the hydrogen evolution performance could be attributed to the formation of a type-II heterojunction, which could not only accelerate the transfer of photoinduced interfacial charges, but also effectively inhibit the recombination of electrons and holes. This work could provide a useful reference to develop an inexpensive and efficient photocatalytic system based on PONb towards H2 production.

Solar light sensitive hybrid Ce4+/3+ doped perovskite magnesium zirconate nano cubes for photocatalytic hydrogen evolution and organic pollutant degradation in water

Dispersion of petite quantity (Mg1−xCexZryO3) of cerium dopant in the lattice of magnesium zirconate (MgZrO3) is an efficient strategy to stimulate solar light photocatalytic activity of the material and achieve superior charge carrier separation. In this research, we demonstrate the tailoring of MgZrO3 to become a solar light sensitive material for the degradation of methyl orange (MO) dye and hydrogen evolution from water. Cerium doped MgZrO3 nanocubes (Mg1−xCexZryO3NCs) showed 93% efficiency for the degradation of MO and was able to show a maximum hydrogen evolution rate of 13,318 µmol h−1 g−1. It was found that, concentration of cerium plays a key role in the overall performance of the photocatalyst. A systematic characterization by Brunauer–Emmett–Teller (BET), Scavenger experiments, Electron Spin Resonance Spectroscopy (ESR), Photoluminescence (PL) and photocurrent measurements of the Mg1−xCexZryO3 NCs showed that, it possesses high surface area, promotes transfer of photo-stimulated electrons and provides rich photo-active centers for the enhanced photocatalytic redox activity. Retention of structure and morphology even after rigorous cycling of the catalyst with respect to MO degradation and hydrogen evolution makes Mg1−xCexZryO3 NCs a robust photocatalytic material.

Efficient photocatalytic H2 evolution over NiS-PCN Z-scheme composites via dual charge transfer pathways

In this study, both narrow band-gap semiconductor NiS and S and O defects modification were introduced into the design of PCN photocatalyst to enhance its photocatalytic performance. The O and S defects, on one hand, provided the higher specific area and more charge separation sites, and constituted the dual fast charge transfer pathways with NiS through the N–C–S–Ni bonds and N–C–O–Ni–S bonds, which greatly increased the carrier transfer kinetics at the interface and restricted the carrier recombination. On the other hand, the midgap level derived from S and O defects also enhanced the absorption of visible light and accommodated more excited electrons. Furthermore, Z-scheme mode could form as Ni2+ species were reduced to metallic Ni0 to acts as charge transfer mediator under irradiation. As such, a maximum hydrogen evolution rate of 1239.3 μmol/g/h was achieved over 5%NiS/SO-Melon composite, nearly 31.4 times the rate of pristine PCN.

Constructing Z-scheme heterojunction with a special electron transfer path and more active sites over MnS/D-PCN for photocatalytic H2 evolution

Given that low hydrogen active sites and serious photoexcited electron-hole recombination greatly limits the solar-to-chemical energy conversion efficiency, a synergistically integrated strategy of the defect engineering and the construction of Z-scheme heterojunction is introduced to the design of PCN photocatalyst, a strand-like polymer carbon nitride, in this work to resolve these problems and enhance the photocatalytic activity. The PHE activity was intimately related to MnS compositions. A maximum hydrogen evolution rate of 670.5 μmol/g/h could be achieved over 5% MnS/D-PCN composite, almost 5 times the rate of D-PCN and 18.4 times higher than that pristine PCN. This high PHE activity of MnS/D-PCN was attributed to the following factors: defects effects and Z-scheme heterojunction. We found that defects sites, on one hand, were the docking sites of MnS through a linkage to bridging the MnS and defected PCN, which offered an efficient spatial transfer path for electron-hole pairs at the interface, on the other hand, acted as the hydrogen evolving centers gathering the excited photoelectrons from D-PCN and MnS. Furthermore, Z-scheme pathway greatly enhanced the photoexcited charge separation due to their enormous driving force in internal electric field of p-n heterojunction.

In situ integration of efficient photocatalyst Cu1.8S/ZnxCd1-xS heterojunction derived from a metal-organic framework

The development of photocatalysts for hydrogen evolution is a promising alternative to industrial hydrogen evolution; however, generation of high active, recyclable, inexpensive heterojunctions are still challenging. Herein, a novel strategy was developed to synthesize non-noble metal co-catalyst/solid solution heterojunctions using metal-organic frameworks (MOFs) as a precursor template. By adjusting the content of MOFs, a series of Cu1.8S/ZnxCd1-xS heterojunctions were obtained, and the Cu1.8S(3.7%)/Zn0.35Cd0.65S sample exhibits a maximum hydrogen evolution rate of 14.27 mmol h−1 g−1 with an apparent quantum yield of 3.7% at 420 nm under visible-light irradiation. Subsequently, the relationship between the heterojunction and photocatalytic activity were investigated by detailed characterizations and density functional theory (DFT) calculations, which reveal that loading Cu1.8S can efficiently extend the light absorption, meanwhile, the electrons can efficiently transfer from Zn0.35Cd0.65S to Cu1.8S, thus resulting more photogenerated electrons participating in surface reactions. This result can be valuable inspirations for the exploitation of advanced materials using rationally designed nanostructures for solar energy conversion.

Coralline-like Ni2P decorated novel tetrapod-bundle Cd0.9Zn0.1S ZB/WZ homojunctions for highly efficient visible-light photocatalytic hydrogen evolution

In this study, Ni2P-Cd0.9Zn0.1S (NPCZS) composites were synthesized by coupling tetrapod bundle Cd0.9Zn0.1S (CZS) and coralline-like Ni2P (NP) via a simple calcination method. CZS shows outstanding activity in photocatalytic hydrogen evolution (1.31 mmol h−1), owing to its unique morphology and heterophase homojunctions (ZB/WZ), which accelerate the separation and transfer of photogenerated charges. After coupling with NP, the photoactivity of NPCZS was enhanced, and the maximum hydrogen evolution rate of 1.88 mmol h−1 was reached at a NP content of 12 wt%, which was 1.43 times higher than that of pure CZS. The experimental results of the photocatalytic activity, viz. photoluminescence spectra, surface photovoltage spectra, and electrochemical test showed that the enhanced photoactivity of NPCZS should be attributed to the synergistic effects of the novel tetrapod-bundle morphology, heterophase homojunctions, and decoration of the NP co-catalyst. Moreover, the as-prepared NPCZS composites exhibited excellent photostability and recyclability. Herein, we propose a possible mechanism for the enhanced photocatalytic activity.