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In this paper, NiCo2S4 was coated on the surface of WS2 of a 1T/2H mixed phase by a two-step hydrothermal method to form an in situ core–shell structure. The unique S-scheme heterojunction of the NiCo2S4@WS2 core–shell composite photocatalyst improved the easy recombination of carriers caused by the narrow band gap of NiCo2S4 and WS2, and improved the photocatalytic hydrogen production performance. The loading ratio of NiCo2S4@WS2, the addition of Eosin Y, and the pH value of TEOA were optimized. Under the optimal conditions, the hydrogen production rate reached 5.814 mmol g−1 h−1, which is about 8.55 times and 3.35 times the hydrogen evolution rates of NiCo2S4 and WS2, respectively. The composite catalyst exhibits excellent charge separation efficiency in photoelectrochemistry, PL and BET tests, carrier transport rate and large specific surface area that can provide more active sites, which are the main factors for the improvement of the hydrogen evolution performance. This paper demonstrates new design strategies to drive efficient photocatalytic hydrogen production by building in situ core–shell structures and optimizing the carrier transport paths, which will yield new insights. [ABSTRACT FROM AUTHOR]

Covalent triazine frameworks (CTFs) containing S heteroatom are promising materials for applications in photocatalysis due to their donor–acceptor-type structures, which can improve the mobility of carriers in polymers. Herein, a series of composites (TTBT-COF@PEGx, x = 10, 20, and 30) were prepared based on CTF containing S heteroatom and polyethylene glycol (PEG) by a two-step reaction. The results show that the photocatalytic hydrogen evolution rate of TTBT-COF@PEG30 is 1.51 times that of pristine TTBT-COF. This significant improvement was attributed to PEG in the pores, which resulted in a stable layered structure, reuced distortion and deformation of the skeleton, and rapid separation and transportation of photogenerated electron holes. [ABSTRACT FROM AUTHOR]

The photocatalytic hydrogen evolution half-reaction (HER) is a promising technology for meeting future energy demands. An excellent photocarrier separation is essential for the HER. Here, a CdS/ZnS composite (CZS) with a dual photocarrier separation channel has been synthesized using the epitaxial growth method to achieve this aim. XRD and TEM show that pre-adsorption of S2− on the CdS surface facilitates the conversion of CdS into ZnS with a larger solubility product, implying a good carrier transport channel between CdS and ZnS. Based on XPS, PL, and photo-deposition experiments, a dual-channel photocarrier separation mechanism has been proposed, which is the source of the great photocarrier separation, and thus the hydrogen evolution rate of the CZS-2 sample (22.05 mmol g−1 h−1) becomes 18.5 and 73.5 times higher than those of CdS and ZnS. The apparent quantum yield (AQY) of CZS-2 at 420 nm is 4.68%. [ABSTRACT FROM AUTHOR]

The development of high-efficiency and low-cost photocatalysts for hydrogen production reactions is very important to solve energy problems. In this paper we study the photocatalytic H2 evolution activity of a CeO2/CoS2 heterojunction catalyst under visible light. Characterization studies such as XRD and XPS proved the successful synthesis of a CeO2/CoS2 catalyst. The composite catalyst with a CeO2 and CoS2 mass ratio of 1 : 20 had the best activity, and the hydrogen evolution rate reached 5172.20 μmol g−1 h−1. BET and UV-Vis DRS characterization showed that the introduction of CeO2 not only increased the specific surface area of the composite catalyst, but also improved the response of the photocatalyst to visible light. In addition, PL and electrochemical experiments showed that the electrons and holes of the CeO2/CoS2 catalyst could be quickly separated and transferred, thereby accelerating the kinetics of the hydrogen evolution reaction. This work provided an experimental basis for designing a composite photocatalyst with high stability and hydrogen production activity. [ABSTRACT FROM AUTHOR]

The development of high-performance and highly stable electrocatalysts is crucial and challenging for the hydrogen evolution reaction (HER). MOFs complexed with SnS2 can form complexes with inserted structures, and their large specific surface area and numerous pores favor mass transfer, exposing the S active sites to more SnS2, improving the utilisation of the active sites and enhancing the catalytic activity for the HER. Structural collapse can be hindered to improve the stability of the HER composites. Herein, six different kinds of SnS2 were synthesized by a hydrothermal method under discrete conditions, and SI8-SnS2 was screened out to have optimal morphology and electrocatalytic performance. Two innovative SnS2@Ni-MOF and SnS2@HKUST-1 as efficient electrocatalysts were synthesized by a facile grinding method for hydrogen generation. SnS2@Ni-MOF and SnS2@HKUST-1 catalysts showed lower overpotentials of 117 mV and 142 mV at 10 mA cm−2 (η10) and smaller Tafel slopes (58 mV dec−1 and 93 mV dec−1) than six different kinds of SnS2, Ni-MOF and HKUST-1 in 0.5 M H2SO4. Meanwhile, the Cdl values for SnS2@Ni-MOF and SnS2@HKUST-1 were estimated to be 11.5 mF cm−2 and 8.0 mF cm−2, and the stabilities of SnS2, Ni-MOF, HKUST-1, SnS2@Ni-MOF, and SnS2@HKUST-1 were tested at a current density of 10 mA cm−2. The current densities of SnS2@Ni-MOF and SnS2@HKUST-1 were stable over 8 h compared to the pure samples, and SEM, XPS tests were run after the HER test, indicating that the materials have excellent electrocatalytic stability. The syntheses of SnS2@Ni-MOF and SnS2@HKUST-1 enhance their intrinsic catalytic activity, and the porous structure promotes mass transfer efficiency, thereby improving the HER performance, which will guide the development of new and promising electrocatalysts for HER. [ABSTRACT FROM AUTHOR]

Subphthalocyanines (SubPcs) have emerged as promising organic dyes for the development of efficient artificial photosynthetic devices, offering intense absorption in the visible region along with excellent charge transport properties. In this study, four novel SubPc derivatives containing carboxylic acid and various peripheral substituents were synthesized as a panchromatic photosensitizer to prepare an efficient and stable TiO2-based photocatalytic system for co-catalyst-free photocatalytic hydrogen evolution. To compare the influence of the nature of the peripheral substituents on photocatalytic activity, SubPc derivatives (coded as SubPc 1–4) were decorated with substituents having different electron-donating capabilities, such as alkyl thio, benzodioxin, amine, and iodo units, respectively. Photocatalytic activities were examined in the presence of TEOA as a sacrificial agent under irradiation with λ > 400 nm without co-catalyst loading. SubPc 1/TiO2 shows the best photocatalytic activity among the SubPc-sensitized photocatalysts, with a hydrogen evolution rate of 0.176 mmol h−1. While the activity of all four SubPc-based photocatalysts increased significantly after 24 h irradiation, notably, SubPc 1/TiO2 exhibited remarkable catalytic activity, achieving a hydrogen evolution rate of 6.017 mmol with a high turnover number (TON) value of 12 279 for hydrogen production. This study highlights the potential of SubPc-based sensitizers for co-catalyst-free photocatalytic H2 production and offers valuable insights into the impact of peripheral units in SubPc/TiO2-based photocatalytic systems. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4), as a carbon support material with excellent stability and abundant active sites, has found widespread applications in various fields, including photocatalytic water splitting, electrolysis of water, and CO2 reduction. Presently, research on the modification of g-C3N4 primarily focuses on atomic doping, defect engineering, and the decoration of metal nanoparticles. In this study, a method involving the high-temperature pyrolysis of a solution containing thiourea and urea was successfully employed to synthesize sulfur-doped porous g-C3N4 (S-C3N4) nanosheets. Subsequently, PtCu nanoparticles were loaded onto the S-C3N4 through a hydrothermal process. In the case of Pt loading of less than half of 20% Pt/C, this catalyst exhibited a low overpotential of only 10 mV at a current density of 10 mA cm−2, which is significantly better than the 35 mV overpotential of 20% Pt/C. Furthermore, after a long period of continuous current stability testing, the overpotential of the catalyst did not increase by more than 30 mV, demonstrating excellent stability. The porous S-C3N4 nanosheets possess a large specific surface area, providing abundant active sites for the HER reaction. This research introduces a fresh method for creating innovative catalysts based on Pt alloys supported by a carbon carrier. [ABSTRACT FROM AUTHOR]

Herein, mesoporous Zn-doped g-C3N4 wrapped CdIn2S4 microsphere nanostructures were fabricated using a simple hydrothermal route. It is found that the CdIn2S4/Zn–g-C3N4 nanocomposite exhibits the most efficient photocatalytic activity for hydrogen evolution. The photocatalytic activity of the CdIn2S4/Zn–g-C3N4 composite presents the optimum performance for hydrogen evolution of 101.74 μmol h−1, which is ∼10.8 and 7.3 times that of pure g-C3N4 and bare CdIn2S4, respectively. The results of varied characterization such as TEM and XPS demonstrate that a tight heterojunction has been successfully built in CdIn2S4/Zn–g-C3N4 nanocomposites, which is highly favorable to limit the recombination of photogenerated electron–hole pairs. Furthermore, Zn could partially replace the C element in the g-C3N4 framework and enhance the separation of photo-induced electrons and holes. Moreover, the incorporation of Zn-doped g-C3N4 nanosheets with mesoporous features considerably improves the photo-stability of CdIn2S4 microspheres. We hope that these CdIn2S4/Zn–g-C3N4 nanocomposites with the tight heterojunction structure may provide new insight into designing novel photocatalysts with high efficiency and excellent stability. [ABSTRACT FROM AUTHOR]

The development of high-efficiency, precious-metal-free electrical catalysts for hydrogen evolution reactions is expected to facilitate the production of hydrolytic hydrogen fuels. Heterogeneous structures with a one-dimensional (1D) morphology exhibit efficient electrocatalytic effects owing to their abundance of active centers in the radial direction and convenient axial charge transfer in interconnected networks. Hence, a 1D MoS2/NiCoP heterogeneous junction for highly efficient hydrogen evolution performance was developed. As expected, the optimized MoS2/NiCoP/NF showed a low overpotential of 148 mV for hydrogen evolution with a current density of 10 mA cm−2 in 1.0 M KOH. Meanwhile, the developed heterogeneous structure exhibited high stability within 50 hours of continuous testing. [ABSTRACT FROM AUTHOR]

Although graphite phase carbon nitride (CN) photocatalysts possess great potential in solving the global energy crisis, their photocatalytic activity is severely affected by sluggish charge dissociation/migration efficiency, a high carrier recombination rate, low active site exposure, and limited visible-light harvesting. Herein, a sulfur doped CN (x-DZCN) was tailored via one-step thermally-induced polymerization of urea with dithizone, which could evolve hydrogen at a rate of 1930 μmol g−1 h−1 (7.1 times higher than that of a single CN). The characterization of the catalyst confirmed that the boosted photocatalytic activity originated from the improved specific surface area from 46 to 61 m2 g−1, broadened visible light harvesting from 470 nm to over 600 nm, more negative conduction band (shift up of 0.54 eV), and promoted charge behavior (improved exciton dissociation and carrier migration efficiency, as well as suppressed carrier recombination capacity). The stable and efficient photocatalytic hydrogen evolution performance verifies the feasibility and potential of this photocatalyst in clean energy production. [ABSTRACT FROM AUTHOR]

The Mn0.2Cd0.8S/NiCo2S4 was prepared using an electrostatic self-assembly method. It was confirmed by analyses of the crystal structure, morphology, and elemental composition. The photoelectrochemical measurement confirmed that Mn0.2Cd0.8S and NiCo2S4 had a close interaction and can form a Schottky barrier. The construction of the Schottky junction speeded up the transport of the photogenerated electrons and inhibited the recombination of the photogenerated electrons and holes. Using Mn0.2Cd0.8S/NiCo2S4, the amount of hydrogen production was higher than with NiCo2S4 and Mn0.2Cd0.8S alone. Different amounts of NiCo2S4 were loaded onto Mn0.2Cd0.8S for the photocatalytic hydrogen production reaction. The hydrogen photocatalytic hydrogen production of Mn0.2Cd0.8S/NiCo2S4-3 was 28.97 times higher than of the Mn0.2Cd0.8S. The Mn0.2Cd0.8S/NiCo2S4 composite exhibited excellent photocatalytic activity and stability, which provided reference values for exploring bimetallic sulfide composite materials, and demonstrated great potential in photocatalytic applications. [ABSTRACT FROM AUTHOR]

Rational construction of low-cost, high-activity electrocatalysts is essential for hydrogen production from electrolytic water. Herein, a Co0.75Mo3S3.75/MoS2 heterogeneous interfacial structure and nitrogen and carbon co-doped on a carbon cloth hydrogen evolution electrocatalyst (NC-Co-MoS2/CC-450) was synthesized by a simple drop coating and pyrolysis method. NC-Co-MoS2/CC-450 exhibits excellent hydrogen evolution performance, achieving a current density of 10 mA cm−2 at only 56 mV, while exhibiting a Faraday efficiency of 99.85% and good stability. Moreover, at high current densities (100 mA cm−2 and 200 mA cm−2), only 155 mV and 220 mV overpotentials are required, respectively, with a small Tafel slope (69.2 mV dec−1). This is due to the intrinsic nitrogen and carbon doped multiphase composite Co0.75Mo3S3.75/MoS2 heterogeneous interface synergistic crystalline-amorphous material system, which generates a large number of lattice defects and exposes a richer active area, accelerating the efficiency of hydrogen evolution and hydrogen desorption. The hydrogen evolution performance of NC-Co-MoS2/CC-450 prepared by the rational design is significantly better than that of many previously reported molybdenum-based catalysts, and this work suggests a further way to continue the development of low-cost and efficient alkaline hydrogen evolution electrocatalysts. [ABSTRACT FROM AUTHOR]

Green hydrogen has emerged as a promising clean energy carrier and renewable energy storage option. It has been promoted as a pivotal solution to the climate crisis and to lowering air pollution. A viable production of green hydrogen requires an efficient and durable non-precious metal electrocatalyst. In light of this, the current study describes the synthesis of an electrocatalyst consisting of Ni and N-doped graphitic carbon (Ni@NC) by a pyrolysis method under an argon atmosphere at different temperatures and the use of a cost-effective and scalable electrode platform for green hydrogen production. The electrocatalyst that was synthesized at 800 °C exhibits an overpotential of 400 mV vs. RHE at a current density of 10 mA cm−2, the Tafel slope of 110 mV decade−1, and good stability for the HER. The charge transfer resistance at the electrode–electrolyte interface is 10.8 Ω in the current study. The symbiotic effect of Ni carbon mixed with nitrogen shows excellent hydrogen evolution reaction (HER) activity. The morphology and structural properties of the electrocatalyst were well-characterized using XRD, FT-IR, Raman, FE-SEM, EDX, TEM, and XPS analysis. The Plastic Chip Electrode (PCE) enhanced the electrocatalytic activity and improved the durability issues, such as carbon corrosion in acidic conditions for the HER by the synergetic effect between the carbon electrode and a component of the catalyst. [ABSTRACT FROM AUTHOR]

The application of photocatalysts for hydrogen production is limited by their low separation efficiency and poor utilization of photogenerated electron–hole pairs. To circumvent such disadvantages, the heterojunctions have been produced to improve the separation of charges and increase the activity of photocatalysts. To date, only a few studies have been conducted to investigate the interaction between the type of heterojunction interface and the photocatalytic hydrogen evolution performance of composites. Herein, the performance of an NH2-UiO-66@MoS2 composite as a photocatalyst for hydrogen production is evaluated. Moreover, NH2-UiO-66@MoS2 heterostructures were prepared through chemical bonding (C-NUM) and physical connection (P-NUM). The photocatalytic hydrogen evolution performance of NH2-UiO-66@0.2MoS2 (C-NUM-0.2) was 1.8 and 1.14 times greater than those of NH2-UiO-66 and P-NUM, respectively. The heterojunction prepared through chemical bonding facilitated the separation of the photogenerated carriers and improved the photocatalytic stability of the composite, demonstrating its potential as a high-performance photocatalyst for hydrogen production. [ABSTRACT FROM AUTHOR]

The possibility of enhancing the hydrogen evolution performance of g-C3N4 through constructing a heterojunction between g-C3N4 and metal oxides or sulfides has been exploited recently. Herein, we report the design of organic composite heterojunctions of g-C3N4 and a soluble dibenzothiophene-S,S-dioxide-containing polymer (PFSO). Constructing bulky heterojunctions by loading the soluble dibenzothiophene-S,S-dioxide-containing polymer on the surface of carbon nitride (g-C3N4) nanosheets plays a significant role in enhancing their photocatalytic activity. Benefiting from the enhanced separation of photogenerated electrons and holes as well as a broadened light-absorption range of the heterojunction design, the composite of g-C3N4/PFSO-1 containing 1 wt% PFSO shows a high hydrogen evolution rate of 149 μmol h−1, which is 30 times higher than that of bare g-C3N4. This study provides insight into fabricating high-performance polymer-heterojunction photocatalysts for H2 production. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation of organic pollutants combined with hydrogen evolution is an effective way to solve the energy crisis and environmental problems. In this work, single s-block (IA group and IIA group) and p-block (IIIA group, IVA group and VA group) metal sites are doped into monolayer GeSe for simultaneous degradation of organic pollutants and hydrogen evolution. Se-rich growth conditions are favorable for metal atoms to substitute Ge atoms. The hydrogen adsorption free energy (ΔGH) of the Bi site on the basal planes of GeSe is −0.037 eV, which is better than those of Pt (ΔGH = −0.08 eV), Se vacancies on the GeSe edge and S vacancies on MoS2 (ΔGH = −0.06 eV). Moreover, Bi doping is superior for producing ˙OH radicals. In addition, Bi doping significantly improves the infrared (IR) light absorption ability. This work confirms the critical role of s-block and p-block metal active centers for hydrogen evolution and degradation of organic pollutants in wastewater. [ABSTRACT FROM AUTHOR]

In the application of graphitic carbon nitride photocatalytic hydrogen production, utilizing transition-metal sulfides instead of noble metals as cocatalysts has broad research prospects. Among them, nickel sulfide is favored by researchers due to its easy preparation, low cost, chemical stability, and excellent photocatalytic performance. Unfortunately, the strong sulfur–hydrogen bonds suppress its development. In this study, we successfully fabricated bimetallic CuNiSx quantum dots onto graphitic carbon nitride by the photochemical deposition method; such a small size can expose more active S sites on the edge. Simultaneously, the introduction of Cu2+ into NiSx can slightly modulate the electronic structure of Ni and S centers, thus weakening the sulfur–hydrogen bonds. Consequently, the average hydrogen evolution rate of CN/CuNiSx QDs achieved 1061 μmol h−1 g−1, which is 4.3 times than that of CN/NiSx QDs (246 μmol h−1 g−1). This research provides a new scenario to design bimetallic sulfide cocatalysts for H2 evolution. [ABSTRACT FROM AUTHOR]

As a research hotspot, 2D-MoS2 has been regarded as a low-cost substitute for platinum, and has fascinated researchers worldwide. Two crystalline phases of MoS2, i.e. the metallic octahedral 1T phase and semiconducting trigonal prismatic 2H phase, have been extensively analysed. In comparison to 2H-MoS2, the 1T phase exhibits enhanced and unique physicochemical properties. Designing a structure with two-dimensional mixed-phase MoS2, i.e. 1T/2H-MoS2 nanosheets, via phase engineering for effective charge separation and migration has received growing interest in the field of photocatalytic hydrogen generation. In this study, by varying the wt% of ammonium bicarbonate via a facile hydrothermal technique, a series of 1T/2H-MoS2 nanosheets have been fabricated. The presence of the corresponding elements, the electronic environment, phase purity, morphology and phase distinction were confirmed by Raman, XPS, XRD and HRTEM analyses. Additionally, the impedance data and the photocurrent density of the photocatalysts verify the efficient charge separation and transfer phenomenon. In accordance with the electrochemical measurements, the developed mixed-phase MoS2 nanosheets exhibit a six times greater current density than 2H-MoS2. Furthermore, the highest response of photocatalytic hydrogen production is observed with the photocatalyst with 79% 1T phase, which is about 17 times greater than that of pristine 2H-MoS2 due to the enrichment of active sites on both the edges and basal plane as well as the enhanced electronic conductivity due to the 1T phase. This study indicates that with the construction of a heterophase, i.e. 1T/2H-MoS2 nanosheets, the photocatalytic hydrogen evolution capability can be boosted, providing new insights regarding these materials. [ABSTRACT FROM AUTHOR]

In order to increase the effective electrochemically active area of electrocatalyst materials and improve their electrocatalytic hydrogen evolution performance, nano-porous Ni–Co alloys were prepared by rapid solidification and dealloying methods. After that, bimetallic sulfides (NiCo2S4) were formed in situ by vapor deposition, then Ru and RuS2 which have excellent intrinsic catalytic activity were adhered to the NiCo2S4 surface by a solvothermal method. Meanwhile, the Ru content was regulated to prepare the NiCo2S4/Ru electrode which was used to figure out the best component and structure for hydrogen evolution. Research shows that when the Ru content reaches 60% (wt/%), the Ru element formed a three-dimensional network flake structure and covered the NiCo2S4 surface. The active area for the reaction (Cdl = 27.6 mF cm−2) and electron transfer ability (Rct = 0.487 Ω cm−2) were increased because of the formation of the heterostructure and surface modification. At a current density of 50 mA cm−2, the NiCo2S4/Ru (60%) composite electrode possessed fast HER kinetics with a hydrogen evolution overpotential of 70 mV and a Tafel slope of 76 mV dec−1, whose electrocatalytic properties are much better than those of NiCo2S4/RuS2 with the same Ru content. The NiCo2S4/Ru (60%) catalyst exhibited superior stability with a small increase in overpotential of just 10 mV after chronopotentiometry tests for 12 h at 10 mA cm−2. [ABSTRACT FROM AUTHOR]

A solvothermal synthesis method using Co(NO3)2 · 6H2O, thiophene dicarboxylic acid (H2tpdc), and 1,4- bis(1-imidazoly) benzene (bib) as raw materials was reported to control the growth of coordination polymers by adjusting the solvent polarity. Then, three coordination polymers with the same conformational unit and ligand and different dimensions were synthesized under three different solvent polarities. In addition, the electrochemical hydrogen evolution reaction (HER) properties of compounds 2D and 3D after high temperature pyrolysis were also investigated. The results show that compound 2D showed a better HER performance than compound 3D. We explained the reasons that compound 2D showed a better HER performance through detailed characterization. [ABSTRACT FROM AUTHOR]

The introduction of oxygen vacancies (Ov) in TiO2 has significant effects on improving the light absorption capacity, expanding the light absorption range and inhibiting photo-generated charge recombination. Here, we used hydrochloric acid and urea mixed with TiO2 hierarchical micro-nanospheres (THS) followed by annealing in an air atmosphere to dope THS with nitrogen and successfully mediated the formation of oxygen defects. Then, the Ni-based promoter is supported on the THS with oxygen vacancy defects by impregnating the metal ions in the solution. Compared with untreated Ni-THS, Ni-THS(Ov) modified by oxygen deficiency has a shorter band gap and photo-generated charge separation efficiency, and its photocatalytic water splitting capacity was also significantly improved. The hydrogen production performance of Ni-THS(Ov) (0.1 wt%) reached 4.88 mmol g−1 h−1 under full-spectrum (UV-vis) irradiation. The synergistic relationship between THS, surface oxygen vacancies and the supported Ni promoters was further investigated. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is an environmentally friendly method for producing hydrogen energy. To help realize the "hydrogen economy", various electrocatalysts have been prepared. Here, we propose a microwave-assisted method to synthesize a CQD-modified ZnS electrocatalyst (ZnS/C) via a one-pot approach, where L -cysteine serves as the sulfur source and carbon source. The characterization results reveal that the loading of CQDs onto ZnS nanoparticles can dramatically increase the electron mobility and active area, playing a fundamental role in obtaining superior HER catalytic performance. Consequently, the as-prepared ZnS/C requires a low overpotential of only 126 mV to achieve a current density of 100 mA cm−2, and it has a low Tafel slope of 28.98 mV dec−1. Moreover, this study not only provides a high-efficiency and potential electrocatalyst for H2 evolution, but is also expected to provide a new design scheme for using CQDs as a cocatalyst to promote charge transfer in nanocomposites. [ABSTRACT FROM AUTHOR]

Recently, much attention has been focused on the development of photocatalysts for hydrogen evolution. Up to now, efficient hydrogen generation is still greatly challenging due to the restraints of the surface redox reaction rate, and the introduction of a co-catalyst is one of the keys to this problem. Here, dual non-noble co-catalysts NixP and Mn3O4 were proposed and prepared on a g-C3N4/red phosphorus (CNP) hybrid structure with a high light adsorption capability by a two-step photo-deposition method. The photo-excited charge on the composite catalyst separate and transfer from C3N4 to red phosphorous due to a type I heterojunction structure. NixP and Mn3O4 act as reductive and oxidative co-catalysts, respectively. The hydrogen production rate was 5851.3 μmol g−1 h−1, 12.4 times that of pure CNP. The consistent catalytic activity in an actual 25 mL flask for hydrogen evolution over eight hours accumulated 245.08 μmol H2 under solar simulated irradiation. This work provides practical reference for the development of a novel inexpensive photocatalyst system. [ABSTRACT FROM AUTHOR]

Currently, two-dimensional (2D) layered transition metal chalcogenides (TMCs), especially MoS2, are attracting widespread attention in the field of water electrolysis. Unfortunately, the catalytic activity of MoS2 is limited to a few edge sites and by its low conductivity. Herein, MoS2/NiS heterostructures possessing a flower-like morphology were constructed via an accurate thermal treatment process to realize precise interface modification. As expected, through the adjunction of a certain amount of polyvinylpyrrolidone, NiS grew uniformly on the surface of MoS2 nanosheets, thereby forming a large number of visual lattice fringes with a specific interplanar spacing, which promoted a higher electron-transfer efficiency. The better electron-transfer efficiency resulted in a better hydrogen evolution reaction performance, providing an overpotential of 158 mV at 10 mA cm−1, a Tafel slope of 128.1 mV dec−1, and significantly long-term durability. Moreover, density functional theory calculation also showed that the precise interface modification of MoS2/NiS heterostructure exhibited more occupations at the Fermi level, which improved the electrical conductivity. Additionally, the MoS2/NiS catalysts achieved a moderately lower hydrogen adsorption energy (ΔGH*), indicating that it had better catalytic hydrogen evolution performance. This work can be extended to design other catalytic materials and for understanding reactions in the fields of energy conversion through theoretical calculations. [ABSTRACT FROM AUTHOR]

There are potential applications for binuclear oxo-bridged iron complexes in biological processes, catalysts, and magnetic materials, and the design of new bridged-iron complexes is important. A new mono-oxo-bridged binuclear iron(III) complex, [(H2O)(bpc)Fe–O–Fe(bpc)(H2O)], is designed and provided by the reaction of FeCl3 with 1,2-bis(pyridine-2-carboxamido)-4,5-dichlorobenzene) (H2bpc) in our group. Structural investigations show that two ions are connected with a Fe–O–Fe angle of 180.0°, so it is a novel linear mono-oxo-bridged iron complex. Magnetic studies indicate that the iron(III) ions are in low spin (ls) states. Electrochemical investigations exhibit that [(H2O)(bpc)Fe–O–Fe(bpc)(H2O)] has FeIV/III, FeIII/II, and FeII/I couples at 0.689, −0.476, and −2.065 V versus Ag/AgNO3, respectively, and can electro-catalyze hydrogen evolution from acetic acid with a rate constant of 7561.95 M−1 s−1. [ABSTRACT FROM AUTHOR]

Herein we have demonstrated the synthesis of nitrogen vacancy enriched exfoliated B-doped g-C3N4 (e-BCN) through a facile thermal exfoliation method, characterized it using different analytical techniques and compared its photocatalytic activity with that of bulk B-doped g-C3N4 (BCN). The decrease in peak intensity and slight shift of the 2 value in the PXRD patterns confirmed the successful exfoliation of bulk BCN to an e-BCN nanosheet. FESEM and HRTEM images also indicated the formation of a thin layered nanosheet of e-BCN as compared to bulk BCN. The PL and EIS data suggested the reduced recombination rate and superior separation capability of the photo-generated charge carriers of e-BCN. The introduction of nitrogen vacancies on the surface of e-BCN is confirmed by the FTIR and XPS analyses. The increased photocurrent density of 524 μA cm−2 displayed by e-BCN indicated the better availability of photo-generated electrons due to the higher separation of charge carriers than in the bulk BCN. The as-prepared e-BCN nanosheet exhibited enhanced photocatalytic performance 1.2 and 3.7 fold greater than that of bulk BCN towards ciprofloxacin degradation and H2 generation, respectively, under visible light irradiation. The excellent photocatalytic behavior of e-BCN was ascribed to the augmented active sites with reduced recombination efficiency and increased separation ability of the photo-induced e−/h+ pairs of the e-BCN nanosheet. This work suggested the facile fabrication of e-BCN through the thermal exfoliation process and its photocatalytic activity towards pollutant degradation and hydrogen evolution. [ABSTRACT FROM AUTHOR]

The design of inexpensive yet effective electrocatalysts for hydrogen evolution reaction (HER) that can function over a wide pH range is highly desirable. In this study, ultralow Ru-incorporated MoS2 nanosheet arrays grown on a carbon cloth (Ru-MoS2/CC) were fabricated for electrocatalytic HER through a simple one-pot hydrothermal method. The effect of the Ru doping amount on the electrochemical performance of MoS2 nanosheets was studied. The best HER activity was achieved with the optimal 0.01-Ru-MoS2/CC catalyst, which provided a low overpotential of 169 or 90 mV for HER at 10 mA cm−2 in 0.5 M H2SO4 or 1.0 M KOH electrolytes, respectively. Moreover, the catalyst was shown to be extremely durable under wide pH electrolytes. This research lays the path for the development of MoS2-based electrocatalysts with strong HER activity across a wide pH range. [ABSTRACT FROM AUTHOR]

Hydrogen evolution catalysts have been studied more in the aspect of iron series elements and less in bismuth metal. Bismuth-based materials are widely used in photocatalysis and CO2 reduction and are rarely applied as electrocatalysts of hydrogen evolution. Meanwhile, the quantum confinement effect and electronic structure of materials will be significantly improved by decreasing the dimension of catalytic materials. Therefore, 2D bismuth nanosheets grown on nickel foam (Bi/NF) by a one-pot method are applied to hydrogen evolution. The catalysts with different reaction times were prepared to optimize the catalytic structure and improve the reactivity. The optimal Bi/NF was obtained with the reaction time of 24 h, which appears as 2D nanosheet arrays. According to the experimental results, the modified Bi/NF displays an overpotential −176 mV at −10 mA cm−2 for hydrogen evolution reaction (HER) in 1 M KOH, which could be used as a working electrode continuously and stably electrolyzed for 10 h. This work looks forward to expanding the application of bismuth metal and broadening the scope of research on hydrogen evolution reactions. In addition, it provides new strategies for constructing efficient and low-cost HER catalysts. [ABSTRACT FROM AUTHOR]

Nearly hexagonal two-dimensional NiCo layered dioxide oxides (NiCo-LDO) were successfully combined with CoWO4 to improve hydrogen production performance. Hexagonal 2D NiCo-LDO was fixed on the surface of CoWO4 to form NiCo-LDO/CoWO4(NCLW) with a p–n heterojunction structure. This structure contributes to the separation and transfer of photoinduced electrons (e−) and holes (h+), prolongs the carrier life, and improves the photocatalytic activity. Photocatalytic experiments showed that the hydrogen production of the p–n heterojunction NCLW under visible light irradiation for 5 h was 77.14 μmol, which was 3.4 times that of pure NiCo-LDO (22.41 μmol) and 40 times that of pure CoWO4 (1.93 μmol). Our discovery of NCLW in the photocatalytic decomposition of aquatic hydrogen will lead to new insights for the design and development of new photocatalytic materials based on layered double oxides (LDO). [ABSTRACT FROM AUTHOR]

S-scheme heterojunction is a new photocatalytic hydrogen production system, which can effectively eliminate useless electron–hole pairs and improve the efficiency of photocatalytic hydrogen production. In this work, Ni-MOF-P(Ni2P)/In2O3 composite photocatalyst was prepared with Ni-MOF-74 and In2O3 by a one-step calcination-phosphating method. The prepared composite catalyst maintained a specific parallelogram-layered structure of Ni-MOF-74 and constructed S-scheme heterojunction. Various characterization techniques such as XRD, SEM, and XPS were used for the characterization of the photocatalyst, which proved that the Ni-MOF-P/In2O3 composite photocatalyst was successfully synthesized for the photocatalytic performance. SEM study showed that In2O3 was excellently compounded on Ni2P, and the cycling experiments and XRD of the sample after the cycling experiment proved their outstanding stability. The amount of hydrogen evolution with a mass ratio of Ni2P and In2O3 of 1 : 0.3 was 494.17 μmol (within 5 h), which is 3 times the hydrogen evolution of Ni-MOF-P. In this work, a novel and simple method for preparing non-noble metal phosphides was proposed for photocatalytic hydrogen evolution using a photocatalyst. [ABSTRACT FROM AUTHOR]

To overcome the sluggish kinetics for catalytic hydrolysis of ammonium borane (AB) to generate hydrogen, it is crucially important to design advanced catalysts with tertiary pore structures and substantial surface-exposed active sites. In this study, we report an architecture engineering strategy to construct nitrogen-rich porous carbon nanosheets with hollow worm-like nanowires (h-NCNWs) using low-cost/non-toxic and easily available graphitic carbon nitride as a self-sacrificing template and nitrogen source. The obtained h-NCNWs enable the uniform deposition of ultrafine Rh nanoparticles (Rh/h-NCNWs). The resultant Rh/h-NCNW catalyst exhibits an excellent hydrogen production performance for AB hydrolysis without any alkali promoters. Specifically, the Rh/h-NCNW catalyst with a low Rh loading of 2.12 wt% delivers much higher catalytic activity with a turnover frequency of 1234 min−1. The hollow worm-like nanowires created in Rh/h-NCNWs can provide diverse flexible channels to facilitate the exposure of copious surface-active sites and mass transport for AB hydrolysis, thereby promoting hydrogen evolution rates. This study provides an efficient strategy to engineer the architecture of the catalyst support for upgrading Rh metal-catalyzed hydrogen evolution from AB hydrolysis. [ABSTRACT FROM AUTHOR]

Metal halide perovskites represented by methylamine lead iodine (MAPbI3) have attracted extensive attention for their excellent performance in the field of photoelectric catalysis. However, the catalytic performance of MAPbI3 is limited due to the severe recombination of electrons and holes. Here, we synthesized hollow MoS2 (H-MoS2) microspheres by the template method and then supported it on the surface of MAPbI3 by electrostatic coupling to obtain H-MoS2/MAPbI3 composites, which showed excellent performance in photocatalytic hydrogen production. Among them, the 15% H-MoS2/MAPbI3 composite showed the highest photocatalytic hydrogen evolution performance, which was 399 μmol h−1, about 260 times that of MAPbI3 (1.53 μmol h−1). The long-term cycling experiments showed that the H-MoS2/MAPbI3 composite retains its activity for at least 16 h. The excellent performance of H-MoS2/MAPbI3 composites was attributed to the efficient shunting of photogenerated electrons and holes by H-MoS2 as a cocatalyst. The results of our study provided a reference for the construction of MAPbI3-based composite heterostructures for efficient photocatalytic hydrogen production. [ABSTRACT FROM AUTHOR]

Tin sulfide has attracted considerable attention due to its adjustable optoelectronic properties. However, few present pieces of literature focus on the photocatalytic water splitting performance of stannous sulfide (SnS), despite several studies that have confirmed it as a nanomaterial theoretically. In this work, Zn-doped SnS with sulfur vacancies has been prepared that exhibits significant performance for photocatalytic hydrogen evolution from water. The vacancy concentration can be regulated by tuning the ratios of tin and sulfur sources during the solvothermal process. Zinc doping and modifying sulfur vacancies can be used to adjust the band structure of SnS to match the hydrogen ion reduction potential. This study shows that engineering the defect concentration and ion dopants has great potential to improve the photocatalytic activity of metal sulfides, providing insights into using SnS photocatalysts for hydrogen evolution by regulating electronic structures with defect engineering. [ABSTRACT FROM AUTHOR]

Due to its appropriate bandgap, Cu2O has been widely studied in the field of photocatalytic hydrogen evolution. The core–shell structure is used to design photocatalytic semiconductor materials, so that the core and the shell can be effectively contacted in the three-dimensional structure. The interaction area between the materials is maximized, the light corrosion of the materials is reduced, and the hydrogen evolution stability and light corrosion resistance of Cu2O composites are improved. In this review, the preparation methods of Cu2O and the effects of surfactants, temperature, pH and other factors on the morphology of Cu2O were reviewed. At the same time, the preparation of core–shell structure Cu2O-metal/nonmetal/metal compound composites and the hydrogen production performance of photocatalysts were studied, which provided a new basis for the development of photocatalytic materials. [ABSTRACT FROM AUTHOR]

Shape anisotropic semiconductors are advanced catalysts for resolving energy crises. However, modification studies are still needed to overcome their intrinsic disadvantages, such as the lack of active sites. With this aim, an excellent hydrogen evolution photocatalyst Rh@Cr2O3-loaded PbMoO4 twenty-six facet polyhedron (PM/Rh@Cr2O3) has been synthesized by a liquid method. Based on XPS, electrochemical investigation and hydrogen evolution reaction (HER) test, it is demonstrated that Rh acts as an electron collector and active site; moreover, Cr2O3 can assist Rh in the dissociation of water. In addition, Cr2O3 can also inhibit the reverse reaction of water splitting as well as the mass transfer of water. In conclusion, the H2 yield rate increased from 0 μmol g−1 h−1 of PbMoO4 (PM) to 704 μmol g−1 h−1 of PM/Rh@Cr2O3, and PM/Rh@Cr2O3 exhibited excellent photo-stability. [ABSTRACT FROM AUTHOR]