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Here, graphdiyne(GDY) was prepared and introduced into bimetallic sulfide Co 1.62 Mo 6 S 8 (CMS) by electrostatic self-assembly method. By fluorescence spectra and electrochemistry, it is observed that the transmission of photo-generated charge carriers in the GDY/CMS composite catalyst was availably regulated, and it was favorable for photocatalytic H 2 evolution. In situ XPS tests show that the charge transfer mechanism between GDY/CMS is consistent with that described by the S-scheme heterojunction. The test results of photocatalytic hydrogen production show that the GDY/CMS composite catalyst has outstanding H 2 evolution performance. The maximum hydrogen yield of GDY/CMS reached 3956.8 μmol g−1, which was 8 times that of GDY. This is because the S-scheme heterojunction is formed between the two catalysts, successfully separating the photo-generated charge carriers and creating more favorable conditions for photogenerated charger transfer. This work indicates that introducing carbon materials into bimetallic sulfides has great application prospects in photocatalysis. • The GDY/CMS S-scheme heterojunction is constructed. • The composite catalyst has very excellent hydrogen production performance. • The separation of photogenerated carrier is effectively promoted. [ABSTRACT FROM AUTHOR]

A novel p-n heterojunction photocatalyst of CoMoO 4 /NiS-3 was constructed by electrostatic adsorption (In CoMoO 4 /NiS-3, the content of CoMoO 4 accounts for 30%). Through SEM and crystal structure, it can be seen that the composite catalyst has a starry flower morphology and is successfully synthesized. The fluorescence emission spectra show that CoMoO 4 /NiS-3 can accelerate the separation rate of photogenerated carriers. The electron transfer mechanism can be determined by ultraviolet characterization and electrochemical methods. Hydrogen evolution experiments can be observed that the amount of hydrogen evolution by the composite catalyst CoMoO 4 /NiS-3 is 225.1 μmol, which is 2.74 and 4.89 times higher than that of the CoMoO 4 and NiS catalysts, respectively. Through the control of the starry flower morphology and the contact interface of p-n heterojunction, the internal electric field is effectively constructed to inhibit the recombination rate of photogenerated carriers, which provides a powerful theoretical model for high performance hydrogen evolution reaction. The formation of p-n heterojunction effectively improves the transmission path of photogenerated carriers and greatly improves the performance of photocatalytic hydrogen evolution. [Display omitted] • The p-n heterojunction between NiS and CoMoO 4 has good stability. • Dispersion of NiS on CoMoO 4 is important for the hydrogen evolution reaction activity. • The electron transport path and hydrogen evolution mechanism of CoMoO 4 /NiS composite catalyst are proposed. • High-efficiency hydrogen evolution is realized through CoMoO 4 /NiS heterojunction. [ABSTRACT FROM AUTHOR]

The p–n type Sm2WO6-Co9S8 heterojunction with two-dimensional coupling interface was successfully synthesized by electrostatic self-assembly. The unique rhombic morphology of Sm2WO6 and Co9S8 nanoparticles also effectively improve the light utilization efficiency. The intervention of Co9S8 enhances the visible light absorption capacity of m2WO6/Co9S8. The Sm2WO6/Co9S8 greatly increases the specific surface area and provides a rich reaction site. Recombination of photogenerated carriers in Sm2WO6/Co9S8 heterojunctions is effectively inhibited. The p–n type Sm2WO6-Co9S8 heterojunction results show that the optimized Sm2WO6/Co9S8 heterojunction exhibits significant hydrogen evolution activity, and the optimal Sm2WO6/Co9S8-25 composite has 117.5 μmol hydrogen evolution activity, it's close to four times Co9S8, close to 143 times Sm2WO6. The stability of the composite Sm2WO6/Co9S8 is the better. Under the built-in electric field induced by p–n heterojunction, using of p–n heterojunction interactions and electron transport modes, the Sm2WO6/Co9S8 can effectively achieve the remarkable effect of its internal carrier separation. This work also provides new opportunities for studying rare earth element tungstate photocatalysts. [ABSTRACT FROM AUTHOR]

With the increasing scarcity of resources, the search for green and available energy has become an urgent need. Among them, photocatalytic decomposition of water to hydrogen production has been widely studied. According to zeta potential and XRD characterization, NiCo2O4 and CuS were successfully reassembled by electrostatic self-assembly to construct S-scheme heterojunction induced by built-in electric site, which can accelerate the reaction. At the same time, under simulated visible light irradiation, the composite catalyst can rapidly decompose aqueous triethanolamine solution to produce hydrogen. The composite catalyst has high photocatalytic activity and shows a durable and efficient hydrogen generation effect. By studying the photogenerated carrier separation and transfer of the catalyst, the results show that the composite catalyst can accelerate the photogenerated carrier separation and transfer, so that it can participate in the photocatalytic reaction faster. It provides various insights into the construction of different heterojunctions in binary composite catalysts. [ABSTRACT FROM AUTHOR]

CuMnO 2 /XMoO 4 (X=Ni, Co, Fe) is a novel high-efficiency photocatalyst, which was synthesized by electrostatic self-assembly method. Under visible light irradiation, by comparing with other eighth main group metals (Fe, Co), it was found by experimental study that adding 30 mg of CuMnO 2 to 100 mg of NiMoO 4 (CuMnO 2 /NiMoO 4 -30%), it has the best hydrogen evolution effect up to 300 μ mol, which is 1.49 and 2.88 times more effective than CuMnO 2 /CoMoO 4 and CuMnO 2 /FeMoO 4 respectively. Meanwhile, the hydrogen evolution yield of CuMnO 2 /NiMoO 4 was about 4 times that of CuMnO 2 and NiMoO 4. The photoelectrochemical and time-resolved fluorescence experiments confirmed the excellent charge separation efficiency of the composite catalyst, and the linear voltammetry curve showed that the composite catalyst had the characteristics of high current response. When CuMnO 2 is loaded on NiMoO 4 , CuMnO 2 /NiMoO 4 exhibits excellent photocatalytic activity due to the formation of Type I heterojunction, which promote charge transfer and effectively improve the separation of electrons and holes. This experiment provides a simple and feasible idea for the study of composite catalysts with high catalytic activity. • The heterojunction between CuMnO 2 and NiMoO 4 has good stability. • Dispersion of CuMnO 2 on NiMoO 4 is important for the HER activity. • Discussion on electron transfer path and hydrogen evolution mechanism. [ABSTRACT FROM AUTHOR]

Supercapacitors (SCs) are widely used in energy storage devices due to their superior power density and long cycle lifetime. However, the limited energy densities of SCs hinder their industrial application to a great extent. In this study, we present a new combination of metallic phosphide–carbon composites, synthesized by directly carbonizing (Ni1−xCox)5TiO7 nanowires via thermal chemical vapor deposition (TCVD) technology. The new method uses one-dimensional (1D) (Ni1−xCox)TiO7 nanowires as precursors and supporters for the in situ growth of intertwined porous CNF microspheres. These 1D nanowires undergo microstructure transformation, resulting in the formation of CoNiP nanoparticles, which act as excellent interconnected catalytic nanoparticles for the growth of porous 3D CNF microspheres. Benefiting from the synergistic effect of a unique 1D/3D structure, the agglomeration of nanoparticles can effectively be prevented. The resulting CNF microspheres exhibit an interconnected conductive matrix and provide a large specific surface area with abundant ion/charge transport channels. Consequently, at a scanning rate of 10 mV s−1, its specific capacitance in 1.0 M Na2SO4 + 0.05 M Fe(CN)63−/4− aqueous solution is as high as 311.7 mF cm−2. Furthermore, the CoNiP@CNFs composite film-based symmetrical SCs show an ultrahigh energy density of 20.08 Wh kg−1 at a power density of 7.20 kW kg−1, along with outstanding cycling stability, with 87.2% capacity retention after 10,000 cycles in soluble redox electrolytes. This work provides a new strategy for designing and applying high-performance binary transition metal phosphide/carbon composites for next-generation energy storage devices. [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]

Promoting the separation of electron and hole plays an important role in photocatalytic hydrogen production. However, single semiconductor materials cannot fully realize their potential due to the rapid recombination of photogenerated carriers. Therefore, in this experiment, a new photocatalyst ZnIn 2 S 4 /NiMoO 4 was prepared by using an electrostatic self-assembly method, which greatly improved the electron-hole recombination phenomenon. After 5 h reaction under visible light irradiation, ZIS/NMO-3 composite catalyst prepared in ethanol showed the best photocatalytic activity, and the hydrogen evolution capacity reached 173.09 μmol. The hydrogen evolution capacity of ZIS/NMO-3 was 2.47 and 25.83 times that of short rod-like NiMoO 4 and microflower-like spherical ZnIn 2 S 4 , respectively. Through some physical characterization and electrochemical experiments, it can be seen that NiMoO 4 and ZnIn 2 S 4 have good composability. Meanwhile, the composite catalyst ZnIn 2 S 4 /NiMoO 4 -3 has high current response characteristics. It can be seen from the fluorescence emission spectra that the composite catalyst presents the lowest peak value, which indicates that ZIS/NMO-3 can effectively inhibit the recombination of photogenerated electrons and holes. When ZnIn 2 S 4 is loaded on NiMoO 4 , the separation of photogenerated carrier will be accelerated due to the formation of heterojunction, thus improving the photocatalytic activity. At the same time, the large specific surface area will also provide more abundant active sites for the composite catalyst, which provides a good condition for photocatalytic hydrogen production. This work provides an efficient, uncomplicated and feasible method for the synthesis of ZIS/NMO-3 composite catalyst with excellent properties. • The heterojunction between ZnIn 2 S 4 and NiMoO 4 has good stability. • Dispersion of ZnIn 2 S 4 on NiMoO 4 is important for the HER activity. • Discussion on electron transfer path and hydrogen evolution mechanism. • High-efficiency hydrogen evolution is realized through ZnIn 2 S 4 /NiMoO 4 heterojunction. [ABSTRACT FROM AUTHOR]

A series of WS2/Co9S8 nanoparticles (NPs) supported on N, S co‐doped mesoporous carbons were prepared via the molten salts process. Glucose, WCl6 and CoCl2 were used as carbon, tungsten and cobalt precursors, respectively. Thiourea were utilized as nitrogen and sulfur precursor. The common inorganic salts were the porogens, which can be removed and recycled. The molar ratio of the precursors can affect the porosities of the catalysts, which can further determine the electrocatalytic performance. The sample of G2.5TWCo shows the best HER performance due to the high electrochemically active surface area and low electrochemical impedance. [ABSTRACT FROM AUTHOR]

Carbon-based single-atom catalysts (SACs) for electrochemical nitrogen reduction reaction (NRR) have received increasing attention due to their sustainable, efficient, and green advantages. However, at present, the research on carbon nanotubes (CNTs)-based NRR catalysts is very limited. In this paper, using FeN3@(n, 0) CNTs (n = 3 ~ 10) as the representative catalysts, we demonstrate that the CNT curvatures will affect the spin polarization of the catalytic active centers, the activation of the adsorbed N2 molecules and the Gibbs free energy barriers for the formation of the critical intermediates in the NRR processes, thus changing the catalytic performance of CNT-based catalysts. Zigzag (8, 0) CNT was taken as the optimal substrate, and twenty transition metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Tc, Ru, Rh, Pd, W, Re, Ir, and Pt) were embedded into (8, 0) CNT via N3 group to construct the NRR catalysts. Their electrocatalytic performance for NRR were examined using DFT calculations, and TcN3@(8, 0) CNT was screened out as the best candidate with a low onset potential of − 0.53 V via the distal mechanism, which is superior to the molecules- or graphene-support Tc catalysts. Further electronic properties analysis shows that the high NRR performance of TcN3@(8, 0) CNT originates from the strong d-2π* interaction between the N2 molecule and Tc atom. TcN3@(8, 0) CNT also exhibits higher selectivity for NRR than the competing hydrogen evolution reaction (HER) process. The present work not only provides a promising catalyst for NRR, but also open up opportunities for further exploring of low-dimensional carbon-based high efficiency electrochemical NRR catalysts. [ABSTRACT FROM AUTHOR]

The development of photocatalysts with efficient hydrogen evolution activity has been the goal for sustainable hydrogen production. In this work, heterojunction composite photocatalyst is formed by hydrothermal coupling of ZnO and Mn 0.2 Cd 0.8 S. Compared with pure ZnO and Mn 0.2 Cd 0.8 S, the composite photocatalyst has the ability to provide more abundant active sites and better photogenerated carriers separation efficiency. The optimized composite photocatalyst shows a 9.36-fold increase in hydrogen evolution activity (4297.99 μmol g−1 h−1) compared to Mn 0.2 Cd 0.8 S (459.31 μmol g−1 h−1) and exhibits excellent cycling stability. Density functional theory calculations identifies Type-II charge transfer path in the composite photocatalyst, achieving effective separation in space of photogenerated electrons from holes and suppressing recombination within the semiconductor. The results show that the construction of Type-II heterojunction in this work achieves a significant enhancement of the hydrogen evolution activity of the photocatalyst by constructing carrier transport channels at the contact interface of the heterojunction. [Display omitted] • Novel and low-cost Mn 0.2 Cd 0.8 S@ZnO structured photocatalyst is prepared by thermal coupling. • Construction of Type-II heterojunction enables efficient separation of photogenerated carriers. • More abundant active sites are exposed on the surface of Mn 0.2 Cd 0.8 S@ZnO. • Composite photocatalysts exhibit significantly enhanced photocatalytic activity and stability. [ABSTRACT FROM AUTHOR]

The hydrothermal preparation of NiCo 2 S 4 /ZnIn 2 S 4 photocatalysts with different mass ratios is studied. Ni-cobalt bimetallic sulfide nanosheets are grown on zinc-indium bimetallic sulfide to form a compact heterojunction. First, both NiCo 2 S 4 and ZnIn 2 S 4 exhibit N-type semiconductor characteristics, a heterojunction formed by both can reduce the surface reaction energy barrier and use its synergy, strengthening the charge self-diffusion between the two semiconductors, it means the formation of a strong electric field. From the electron transfer path and band structure, NiCo 2 S 4 /ZnIn 2 S 4 has S-scheme heterojunction characteristics. NiCo 2 S 4 is a reducing photocatalyst (RP), and ZnIn 2 S 4 is an oxidative photocatalyst (OP). Under the action of built-in electric field (BIEF), strong photogenic electrons and holes exist in CB of RP (NiCo 2 S 4) and VB of OP (ZnIn 2 S 4). Thus, the overall redox capacity of the NiCo 2 S 4 /ZnIn 2 S 4 heterojunction is enhanced. Using visible light, the composite material can be used for photocatalytic hydrogen production. It is further shown that the composite material has a good effect in photocatalytic hydrogen production under the sensitizer eosin Y (EY) system. The optimal hydrogen production is about 221.75 μmol when the mass ratios of NiCo 2 S 4 /ZnIn 2 S 4 is 20%, and the photocatalytic activity of the composite is about 47 times that of ZnIn 2 S 4. Notably, the stability of the composites is the better. A reasonable photo-catalytic mechanism is proposed based on the band gap and photoelectrochemical properties of heterojunction. • Nanosheets NiCo 2 S 4 innovatively decorated on globular structure ZnIn 2 S 4 form S-scheme heterojunction. • The morphology of nanosheets NiCo 2 S 4 is innovative in the field of NiCo 2 S 4 /ZnIn 2 S 4 photocatalysis. • The heterojunction can short transfer route to promote electron efficient transport. • Dispersion of NiCo 2 S 4 on ZnIn 2 S 4 is important for the heterojunction HER activity and stability. [ABSTRACT FROM AUTHOR]

A molten salts strategy was developed to synthesize Co2P nanoparticles (NPs) embedded N, P co‐doped mesoporous carbon. No solvent was introduced in the synthesis process. Moreover, the common inorganic salts were utilized as the templates, which could be removed and recycled by water washing. The characterization results exhibited that the final products consisted of Co2P NPs and carbon. The amounts of the salts determined the porosities of the as‐obtained sample, which further effect the activities for electrocatalytic hydrogen evolution reaction (HER). The optimal sample of GUCo‐0.2NaCl showed the best HER performance among these as‐obtained electrocatalysts, including small Tafel slope and low overpotential. [ABSTRACT FROM AUTHOR]

The study of environmentally friendly semiconductor photocatalysts has important practical significance for efficient photocatalytic hydrogen evolution. In this experiment, type II heterojunction NiCo-LDH/CeO2 was prepared by in situ loading, and the NiCo-LDH/CeO2 catalyst showed good activity under simulated sunlight irradiation. Under simulated visible light irradiation, its hydrogen production rate reached 2.7 mmol h−1 g−1, which was higher than that of NiCo-LDH (0.86 mmol h−1 g−1). Through a series of characterization data, it can be concluded that the heterojunction successfully constructed by the close contact between NiCo-LDH and CeO2 accelerates the separation of photogenerated electrons and holes and can effectively inhibit the recombination of the two so that more electrons are involved in the hydrogen evolution reaction. The material has good interfacial charge transfer performance, which improves the photocatalytic performance. This work can provide an effective method for the research and development of NiCo-LDH. [ABSTRACT FROM AUTHOR]

A solvent-free strategy was found to prepare MoP nanoparticle (NP) embedded, N, P co-doped carbon. The characterization results revealed that the mass ratios of the precursors can determine the samples' structures and can affect the electrocatalytic activities towards the hydrogen evolution reaction (HER). These catalysts showed excellent HER performance. [ABSTRACT FROM AUTHOR]

We developed a molten salts process to prepare Co9S8 nanoparticles (NPs) entrapped, S, N co‐doped carbons. Cobalt chloride was used as the cobalt source. The melamine‐formaldehyde (MF) resin provided the carbon source and nitrogen source, and thiourea provided sulfur source. In addition, common inorganic salts were added as templates to generate pores. The characterization results showed that the prepared materials contained high contents of N, S and Co, and were mesoporous composites. At the same time, the porosity of electrocatalyst depended on the type of salt and the mass ratio of precursor to salt, which further affected the electrocatalytic activity of hydrogen evolution reaction (HER). The best prepared catalyst showed excellent HER performance. The onset overpotential of the catalyst was low (33 mV) and had a small Tafel slope (61.1 mV dec−1), in addition to good stability in alkaline media. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn 0.2 Cd 0.8 S formed a stable heterojunction with CeO 2. • Mn 0.2 Cd 0.8 S/CeO 2 achieves efficient photocatalytic HER. • The reaction mechanism of the catalyst is speculated. • The recombination of photogenerated carriers was effectively suppressed. • The band gap and state density of catalyst were calculated by DFT. The Mn 0.2 Cd 0.8 S/CeO 2 heterojunction is synthesized by means of hydrothermal coupling. Short rod-like Mn 0.2 Cd 0.8 S is wrapped in leaf like CeO 2 to construct a tight heterointerface, which stimulated the photocatalytic activity to the great extent. Due to the remarkable catalytic and electrochemical properties of Mn 0.2 Cd 0.8 S, the CeO 2 surface active site is driven. CeO 2 has excellent specific surface area, suitable pore volume aperture and Mn 0.2 Cd 0.8 S match to optimize the internal interface charge transfer path. At the same time, the heterointerface can coordinate the interface electron flow and promote the H 2 reduction ability. The results show that the optimal hydrogen production of Mn 0.2 Cd 0.8 S/CeO 2 with S-type heterostructure is 291.8 μmol, and the internal lattice and surface morphology of Mn 0.2 Cd 0.8 S/CeO 2 are not easily damaged due to good catalytic stability. The photocatalytic mechanism of Mn 0.2 Cd 0.8 S/CeO 2 is studied by finding the short distance interfacial charge transfer path and enriching the photogenerated electrons required for hydrogen evolution. [ABSTRACT FROM AUTHOR]

In the field of photocatalysis, the recombination of photogenerated holes and electrons is still an urgent problem to be solved. Among many measures, constructing heterojunction is one of the commonly used methods to adjust the carrier transfer path and accelerate the electron transfer. In this paper, Fe2O3/NiS p–n heterojunction composite catalyst was synthesized by solvothermal method. Through XRD, SEM and XPS characterization and analysis, it was found that the composite catalyst was composed of NiS nanoparticles and hexagonal Fe2O3 nanosheets. The specific surface area test results showed that Fe2O3/NiS had a larger specific surface area, which could provide more active sites for the H2 production reaction. By adjusting the ratio between Fe2O3 and NiS, the optimal composite photocatalyst was obtained. The hydrogen production rate reached 5.82 mmol g−1 h−1, which was 58.2× that of single Fe2O3 and 2.7× that of single NiS. The NiS p-type semiconductor and Fe2O3n-type semiconductor were successfully coupled. Under the action of the p–n heterojunction interface and the built-in electric field, the photogenerated electrons and holes of the composite catalyst could be quickly transferred and separated. This result was also confirmed by a series of characterizations such as photoluminescence spectrum and photoelectrochemical experiments. Fe2O3 and NiS formed p–n heterojunctions, and the mixed interface structure between them provided a new hydrogen-producing active center for each. Moreover, the construction of p–n heterojunction promoted the separation of electrons (e−) and holes (h+), so that Fe2O3/NiS exhibited excellent hydrogen evolution performance. [ABSTRACT FROM AUTHOR]

The construction of heterojunctions can effectively improve the electron transport rate and photocatalytic activity. In this work, nanoflower-like S-scheme heterojunction MoS2/NiAl-LDH was successfully synthesized. The results indicated that the hydrogen yield of the MoS2/NiAl-LDH composite catalyst reached 229.5 μmol in 5 hours under visible light irradiation by adjusting the pH value of the sacrificial agent and the amount of eosin. The crystal structure and morphological characteristics of the composite were analyzed by XRD, SEM and TEM. The visible light response degree and charge separation and transfer rates of photogenerated carriers of the composite were analyzed by UV-Vis DRS, PL and electrochemistry. The electronic transfer path was also analyzed by XPS. The construction of S-scheme heterojunctions can realize effective separation of electron–hole pairs and ensure that the photo-induced carriers with the strongest redox ability can be retained to participate in the photocatalytic reaction. In addition, the feasible mechanism of photocatalytic hydrogen evolution is given. This work will provide different insights into the enhancement of hydrogen evolution by heterojunctions formed by binary semiconductors. [ABSTRACT FROM AUTHOR]

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]

Transition metal phosphides (TMPs), as an environmentally friendly non-noble metal cocatalyst, play a key role in promoting photocatalytic hydrogen evolution. In this work, three metal phosphating compounds (NiCoP, Ni2P, and Co2P) were synthesized by solvothermal method using red phosphorus as a phosphorus source. The three kinds of co-catalysts were individually loaded onto Zn0.5Cd0.5S by physical agitation method to form binary nanocomposites (ZnCdS/TMPs). The results showed that the three composite photocatalysts all showed excellent HER performance in the Na2S/Na2SO3 sacrifice solution. Among them, the hydrogen production rate of ZnCdS/NiCoP-5% reached 64 μmol at 5 h, which was significantly higher than that of pure Zn0.5Cd0.5S, ZnCdS/Ni2P-5%, and ZnCdS/Co2P-5%. According to the results of various characterization techniques, NiCoP nanoparticles provide more active sites for Zn0.5Cd0.5S and the composite photocatalytic materials exhibit excellent hydrogen evolution performance. Moreover, the Schottky barrier between Zn0.5Cd0.5S and NiCoP nanoparticles effectively enhances the charge separation rate, thus promoting the improvement of photocatalytic hydrogen evolution. Therefore, low-cost transition metal phosphide as a cocatalyst has broad prospects in the field of photocatalysis. [ABSTRACT FROM AUTHOR]

Bimetallic oxides have attracted extensive attention due to their excellent photocatalytic properties. Co2NiO4 has good electrical activity which can effectively regulate the distribution of charge. The scanning electron microscope and transmission electron microscope images of Co2NiO4 showed two-dimensional uniform lamellar morphology. This kind of morphology could provide a larger specific surface area, which was conducive to improving photocatalytic water decomposing and hydrogen evolution. In addition, we combined Co2NiO4 with NiWO4 to improve the conductivity of Co2NiO4 and the position of Fermi energy level, forming a p-n-type heterojunction, effectively promoting the interface charge transfer through the internal electric field, and inhibiting the electron–hole pair recombination. The photocatalytic hydrogen production of CN/NW-3 in the sensitized system reached 341.83 μmol for 5 h, which was 19 times that of pure Co2NiO4. At the same time, UV–Vis diffuse reflection and Mott–Schottky curve were used to further determine the conduction band (CB) and valence band (VB) positions of Co2NiO4 and NiWO4, which formed a charge transport path with higher separation and transfer efficiency. This work highlights the high-efficient photocatalytic hydrogen production performance of CN/NW p-n heterojunction. Co2NiO4 and NiWO4 form p-n heterojunction, and the synergy between them provides a new hydrogen-producing active center for each. [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]

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]

A novel red phosphorus/nickel cobalt layered double hydroxide (RP/NiCo-LDH) heterojunction was successfully prepared and exhibited an excellent photocatalytic performance for hydrogen evolution. The formation of an S-scheme between purified RP and the NiCo–LDH effectively promoted the generation of an electric field at the interface between RP and the NiCo-LDH. The existence of an internal electric field can promote the migration of photoexcited carriers from the conduction band of pure RP to the valence band of the NiCo-LDH, thus effectively inhibiting the recombination efficiency of electron/hole pairs. Under simulated visible-light irradiation, the hydrogen evolution activity of the 70 wt% NiCo-LDH composite catalyst RP/NiCo-LDH reached 32.8 mmol g−1 at 5 h, which was 6.41 times that of pure NiCo-LDH. The RP/NiCo-LDH composite photocatalyst was characterized using a series of characterization techniques. Among them, UV absorption spectra, fluorescence and photoelectrochemical experiments showed that the absorption rate and the electron-transfer rate of the RP/NiCo-LDH composite catalyst were significantly higher than that of the pure RP and NiCo-LDH. Therefore, RP/NiCo-LDH composite photocatalysts open up a new route for the development of non-noble metal photocatalysts. [ABSTRACT FROM AUTHOR]

A series of Co9S8 nanoparticles (NPs) embedded, N, S co‐doped mesoporous carbons were synthesized by the combination of evaporation induced self‐assembly (EISA) method and simple pyrolysis method. Melamine formaldehyde (MF) resin was used as carbon and nitrogen precursor. CoCl2 and thiourea were utilized as cobalt and sulfur precursors, respectively. The as‐obtained samples possessed mesoporous structure. The optimized sample of MF4.0T6.0 exhibited excellent electrochemical performance towards hydrogen evolution reaction (HER) in wide pH range, which achieved a current density of 10 mA cm‐2 at 163 mV (pH 0), 149 mV (pH 14), and 325 mV (pH 7). [ABSTRACT FROM AUTHOR]

A novel composite photocatalyst RP/BP/Co-MOF was prepared for highly efficient photocatalytic hydrogen evolution. Metal–organic frameworks Co-MOF was used as an electron transfer medium in composite photocatalyst, it accelerated the electron transfer rate between red phosphorus and black phosphorus. It had played an important role in RP/BP Z-scheme heterojunction system. Under simulated visible light exposure, the hydrogen production amount of the composite photocatalyst RP/BP/Co-MOF was 632.4 μmol in 5 h, which was 44.82 times as much as RP/BP flake. At the same time, a series of characterization of the composite photocatalyst was carried out. The results of photoluminescent spectroscopy and electrochemical measurements showed that the combination of RP/BP Z-scheme heterojunction and 2D sheet Co-MOF could effectively inhibit the recombination of photogenerated carriers, promote the transfer of electrons and improve the photocatalytic activity of the composite photocatalyst. This work provided an important way to develop a low-cost photocatalyst with high hydrogen yield. Red/Black phosphorus Z-Scheme heterogeneous junction modulated by Co-MOF for enhanced photocatalytic hydrogen evolution. The enlarged part shows the structure structure of Co-MOF. C: black; N: light blue; Co: purple. Hydrogen atoms are omitted for clarity. [ABSTRACT FROM AUTHOR]

Due to the poor photocatalytic hydrogen evolution ability of pure CdS, we need to develop a photocatalytic hydrogen evolution catalyst with high activity and no precious metal doping. Therefore, in this article, we used a simple hydrothermal synthesis of CdS nanoparticles, using water as a carrier, loading a small amount of amorphous CoS, by changing the loading ratio of amorphous CoS, synthesized TYPE–II type heterojunction composite catalyst CCS. The successful synthesis of the composite catalyst CCS was verified by XRD, SEM and other characterization methods. UV–vis, PL and other characterization showed that the supported amorphous CoS could significantly improve the photocatalytic activity of CdS, and the photochemical detection also showed that the performance of composite catalyst CCS was better than that of pure CdS. Using Na2S and Na2SO3 mixed solution as electron sacrificial agent, the hydrogen production performance of CCS composite catalyst was determined through hydrogen evolution experiment and cyclic stability experiment. It was found that the sacrificial agent had a great promotion effect on the hydrogen production performance of photocatalyst. It was found that the hydrogen production rate of the composite catalyst could reach 2.01 mmol·g−1·h−1, which was 6.3 times of the pure CdS. This study offers a novel approach for the design of amorphous–based nanostructures as efficient hydrogen evolution cocatalysts. First, CdS are excited by light, consuming S2− and SO32− ions in the sacrificial agent, generating a large number of electrons and holes. Due to the energy difference between the conducting band (CB) of CdS and amorphous CoS, the electrons are transferred from the surface of CdS to the conducting band (CB) of amorphous CoS, while the electrons obtained from water and H+ in the sacrificial agent are reduced to H2. The amorphous CoS is used as the transfer medium of electron acceptor, and the synergistic effect between heterojunctions is used to improve the charge separation efficiency and electron transfer rate. Therefore, the photocatalytic hydrogen production effect of the composite catalyst CCS–7 has been greatly improved. [ABSTRACT FROM AUTHOR]

Using sunlight to catalyze water to produce H 2 is a key technology to solve the problem of energy shortage. In this research, perovskite-type NiMnO 3 and Ni 3 S 4 was recombined through secondary hydrothermal treatment. The optimal hydrogen evolution for composite materials NiMnO 3 /Ni 3 S 4 is 3.76 μmol mg−1 h−1, that 3.7 and 4 times more than that of two monomer materials, respectively. After four cycles of catalytic experiments, proving the high efficiency and stability of the composite catalyst. The characteristics of fluorescence spectroscopy and electrochemistry have confirmed the existence of p-n heterostructures, the excellent catalytic performance is related to the built-in electric field (accelerating the separation and utilization of photocharges) generated by the combination of NiMnO 3 and Ni 3 S 4. Strengthening the performance of the catalyst by constructing a heterostructure is an effective modification strategy and has positive application value in the fields of sensors and optoelectronics. [Display omitted] • The three-dimensional structure of the catalyst has a large number of active sites. • Simple hydrothermal method to uniformly deposit NiMnO 3 on the surface of Ni 3 S 4. • The built-in electric field in the heterostructure promotes charge separation. • p-n heterojunction improves the hydrogen production performance of the catalyst. [ABSTRACT FROM AUTHOR]

A solvent‐free strategy was developed to synthesize MoS2/Mo2C embedded, N, S co‐doped carbon via a green and environmentally friendly process. The precursors were blended and carbonized under the inert atmosphere. Water and other solvents were not involved in the whole synthesis process. According to the characterization results, the as‐received samples consisted of Mo2C, MoS2, and carbon with mesoporous structures. Moreover, the obtained sample possessed a high BET surface area (373.3 m2 g−1), as well as high electrochemical active surface area (145.4 mF cm−2). When utilized as the electrocatalyst towards hydrogen evolution reaction (HER), the optimal sample of T2.0G4.0Mo1.0 revealed superior electrochemical activity in alkaline media, which could show a low overpotential and an excellent stability. [ABSTRACT FROM AUTHOR]

The exploration of Z-scheme heterojunction photocatalysts is considered crucial to improve the efficiency of photocatalytic hydrogen evolution. In this work, ZSN with a Z-scheme heterojunction is prepared by a two-step hydrothermal method. Through the study of the surface morphology, crystallization properties, surface chemistry and optical properties of the photocatalyst, it is known that the ZSN heterojunction can improve the visible light capture ability, prolong the service life of charges, improve the efficiency of charge separation, and improve the photocatalytic performance. Under visible light irradiation, the amount of hydrogen evolution of the optimized 2-ZSN is 74 μmol, 37 times that of the pure ZnS (2 μmol). The results of photoluminescence (PL), ultraviolet-visible (UV-Visible) and electrochemical techniques show that the Z-scheme mechanism is advantageous to the separation of photogenic carriers as well as the hole transfer and separation. This work provides a reliable strategy for constructing efficient Z-scheme heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

Semiconductor heterojunction has been regarded as one of the most promising strategies to produce efficient photocatalysts, which construction can be beneficial to accelerate the separation of photo-induced charge carriers for boosting photocatalytic H 2 production. Herein, noble-metal-free MoS 2 was adopted as a co-catalyst to construct a ternary Bi 2 S 3 /MoS 2 /P25 heterojunction for boosting electrons transfer and further evaluating for H 2 production from water under solar irradiation. Due to the synergistic effects of the co-catalyst and heterojunction in the Bi 2 S 3 /MoS 2 /P25 system, the optimal MoS 2 /P25/Bi 2 S 3 sample provides the excellent photocatalytic activity of H 2 evolution rate (13.0 mmol g−1 h−1), which can be ascribed to the positive synergetic effects of improved charge transfer and efficient separation of the light-induced charge carriers of MoS 2 /P25/Bi 2 S 3 arose from the dual-channel charges transfer path. By taking full advantage of ternary heterojunction and co-catalyst for promoting H 2 production, this work guarantees insights into the low-cost, large-scale production of commercial TiO 2 -based ternary composite materials applied in solar photocatalytic hydrogen production. [ABSTRACT FROM AUTHOR]

Overall dye-sensitized photocatalytic HER system based on g-C 3 N 4 and 2D Co MOF doped by Sm achieved effective photocatalytic H 2 evolution. • An overall dye-sensitized system was constructed for efficient photocatalytic HER. • 2D Co MOF and protonated g-C 3 N 4 formed a 2D/2D heterojunction. • Protonated g-C 3 N 4 preferentially adsorbed EY molecules. • Sm element doping 2D Co MOF further improved carrier separation. A dye-sensitive photocatalytic H 2 evolution reaction (HER) system with photogenerated carrier directed conduction was constructed. The protonated g-C 3 N 4 combines with the sheet-like Co MOF to form a 2D/2D heterojunction via electrostatic self-assembly. The protonated g-C 3 N 4 and 2D Co-MOF directionally adsorb Eosin Y (EY) and triethanolamine (TEOA) molecules through hydrogen bond and complexation to achieve a whole photocatalytic system. The integral structure effectively facilitates the utilization of dye sensitizer and hole sacrificial agent to achieve the effective and stable photocatalytic H 2 evolution capacity. The photocatalytic hydrogen evolution rate of g-C 3 N 4 after protonation is 1.88 times as high as that of the original g-C 3 N 4. On the basis of 2D/2D heterojunction, Co MOF is doped with rare earth element Sm. The 4f electrons and the difference valences (Sm3+ and Co2+) further suppress the reorganization of photogenerated excitons to achieve highly efficient photocatalytic HER. The directional coupling of sensitizer and electron sacrificial agent combined with rare earth element doping makes the photocatalytic HER rate of the composite material reached 73.42 μmol.h−1 within 5 h under simulated sunlight. [ABSTRACT FROM AUTHOR]

One of the most effective methods to improve electron-transfer efficiency and photocatalytic reaction activity is to construct a photocatalyst with a heterojunction interface. Herein, a WO3/CoS2 n–n heterojunction composite catalyst was synthesized, and used in photocatalytic hydrogen evolution, and was optimized by adjusting the pH of the triethanolamine solution, the amount of Eosin Y added, and the content of WO3 in the composite catalyst. After 5 h of photocatalytic reaction, WO3/CoS2 (WCS-2) had a H2 production of 221.15 μmol, which was 80.41 times that of single WO3 and 2.17 times that of CoS2, and had good stability. XRD, SEM, TEM, and XPS characterization results indicated that WO3/CoS2 was successfully prepared. Fluorescence test and electrochemical test results showed that the WO3/CoS2 catalyst had a higher photoelectron transfer efficiency. Finally, it is pointed out that WO3/CoS2 enhanced the photocatalytic activity, which may be due to the electron migration of WO3 and CoS2 following the Z-scheme mechanism. This work presents a new idea for constructing n–n heterojunction to enhance the activity in photocatalytic hydrogen production. [ABSTRACT FROM AUTHOR]

Amorphous/low-crystalline core/shell-type nanoparticles (Pd–P/Pt–Ni NPs) were prepared via a facile seed-mediated method. After acid treatment, the NPs exhibited self-improved catalysis for hydrogen evolution during electrolysis in an alkaline medium. [ABSTRACT FROM AUTHOR]

Previous reports indicate that the catalyst CdxZn1−xS shows good activity and reliability in the process of photocatalytic hydrogen production. However, it is still a challenge to design a cost-effective catalyst to replace the traditional CdxZn1−xS. In this work, Roman broccoli Cd0.8Zn0.2S-2 was successfully prepared through reasonable adjustment and control of the amount of raw materials. In the photocatalytic hydrogen evolution test, the amount of hydrogen evolution of CZS-2 was 1.24, 1.34, 2.06, and 2.24 times that of CZS-1, CZS-3, CZS-4, and CZS-5, respectively. This is because Cd0.8Zn0.2S-2 has more excellent synergy inside. Theoretical and experimental studies show that, based on rational design, the optical and electrical properties of the CZS-2 structure have been substantially improved (based on UV–Visible diffusion and photoluminescence). The mechanism of the study shows that the photocatalytic hydrogen evolution activity of CZS-2 is effectively improved due to the favorable energy band of effective charge transfer inside CZS-2. In this work, Roman broccoli-like CZS-2 provides a new research direction for photocatalytic water decomposition. [ABSTRACT FROM AUTHOR]

Research into catalytic materials that convert light energy into chemical energy by decomposing water still faces great difficulties. CuNi2S4 has attracted public attention due to its unique morphology; however, its high electron–hole recombination rate and weak charge separation efficiency limit its use in the field of catalysis. Herein, CoWO4 material is synthesized in situ on a CuNi2S4 surface by a hydrothermal method; the Z-type heterointerface constructed by the surface contact of the two materials under fusion shows a huge promotion effect on the catalytic ability. The performance (3754.3 μmol g−1 h−1) of the composite material (CW/CNS-12%) reached 42 and 6 times those of the two monomer materials, respectively, and the excellent catalytic ability of the composite is also reflected in its long-term stability. The experimental data proves that the modification of CuNi2S4 by building a heterostructure can improve the specific surface area of the material and the amount of carriers it generates. The charge transfer caused by the existence of the heterojunction hinders the recombination of carriers and holes; fluorescence and electrochemical characterization further confirms the charge transfer process in the Z-type heterojunction. This research provides new insights to promote catalytic performance by building heterostructures between monomer materials. [ABSTRACT FROM AUTHOR]

Covalent triazine frameworks (CTFs) have emerged as new candidate materials in various research areas such as catalysis, gas separation storage, and energy-related organic devices due to their easy functionalization, high thermal and chemical stability, and permanent porosity. Herein, we report the successful synthesis of a CTF rich in cyano groups (CTF-CN) by the solvothermal condensation of 2,3,6,7-tetrabromonapthalene (TBNDA), Na2(1,1-dicyanoethene-2,2-dithiolate), and 1,3,5-tris-(4-aminophenyl)-triazine (TAPT) at 120°C. XRD, SEM, and TEM characterization studies revealed CTF-CN to be amorphous and composed of ultrathin 2D sheets. CTF-CN possessed strong absorption at visible wavelengths, with UV-vis measurements suggesting a band gap energy in the range 2.7-2.9 eV. A 5 wt.% Pt/CTF-CN was found to be a promising photocatalyst for hydrogen production, affording a rate of 487.6 μmol g-1 h-1 in a H2O/TEOA/CH3OH solution under visible light. The photocatalytic activity of CTF-CN was benchmarked against g-C3N4 for meaningful assessment of performance. Importantly, the 5 wt.% Pt/CTF-CN photocatalyst exhibited excellent thermal and photocatalytic stability. Further, as a nitrogen-rich porous 2D material, CTF-CN represents a potential platform for the development of novel electrode material for fuel cells and metal ion batteries. [ABSTRACT FROM AUTHOR]

The prepared non-precious metal composite catalyst uses Eosin Y as a sensitizer; triethanolamine is an electronic sacrificial agent. It has high efficiency and stable catalytic activity. CoS/ZnWO4 has a stronger ability to absorb visible light and greater photocatalytic hydrogen evolution activity than ZnWO4. The hydrogen production rate of CoS/ZnWO4 can reach 7.12 mmol/h/g, and the catalytic activity is 3.6 times that of CoS. The excellent catalytic activity of the composite catalyst is due to its proper band gap. [ABSTRACT FROM AUTHOR]

The expansion of the optical response range and the high photoelectron holes separation and the transfer efficiency are prerequisites for the excellent hydrogen evolution performance of the catalyst. In this paper, amorphous CoSx is combined with rare-earth complex LaMnO3 and under the characterization of SEM, TEM, XRD and XPS, the successful synthesis of the composite catalyst was demonstrated; characterization results by UV–Vis, BET and electrochemical workstations show that the composite material exposes more active sites, and the close contact interface formed between the two effectively improves the separation and transmission of photogenerated carriers, and the ability of the composite material to sense light is also significantly enhanced. After optimizing the hydrogen production conditions of the composite catalyst, the hydrogen production under visible light (≥ 420 nm) for 5 h reached 458.8 μmol, which was about 6.8 and 4.5 times that of pure LaMnO3 and CoSx, and the hydrogen evolution stability of the material is very good. Studies have shown that amorphous CoSx is a good material that can replace precious metals for hydrogen production. [ABSTRACT FROM AUTHOR]

In this study, a CoS/NiMoO4 composite catalyst with good TYPE-II heterojunction was prepared by hydrothermal method with NiMoO4 nanorods, with water as a medium to load small amount of amorphous CoS, by changing the loading amounts of amorphous CoS. X-ray diffraction, UV–Visible diffuse reflection and other characteristics indicate that doped amorphous CoS can significantly improve the photocatalytic performance of NiMoO4, and the charge separation and electron transfer efficiency of composite catalysts detected by photoelectric chemistry are also significantly improved compared with NiMoO4. The photocatalytic activity and stability of the composite catalyst were studied by hydrogen evolution experiment. The hydrogen production rate of the composite catalyst can reach 338 μmol, which is 3.23 times higher than pure NiMoO4. This simple hydrothermal synthesis of photocatalytic materials provides new ideas and methods for the design and development of new composite photocatalysts. [ABSTRACT FROM AUTHOR]

A photocatalytic material, NiCo2S4@Ni2P, with a unique hollow core–shell structure based on hollow spherical NiCo2S4, which has a structure that is greatly advantageous for heterogeneous photocatalytic reactions, was successfully prepared. The unique hollow core–shell structure formed a homogeneous surface heterojunction, which caused the composite photocatalytic material to exhibit better photocatalytic HER activity and stability than the initial NiCo2S4 in the dye-sensitized system. The photocatalytic HER rate of the optimal photocatalytic material, NiCo2S4@Ni2P 10%, reached 77.97 μmol h−1via the optimization of the photocatalytic H2 evolution performance. XRD and XPS were used to study the crystal structure and valence state of the photocatalytic material, respectively. Additionally, its morphology and structure were observed by SEM and TEM, respectively. The CB and VB potentials were derived by combining empirical formulas based on the UV-vis DRS data. Finally, the photocatalytic HER mechanism was investigated by photoelectrochemical and PL tests combined with the above data. [ABSTRACT FROM AUTHOR]

In this study, a novel molybdenum disulfide modified nickel titanate composite photocatalyst MoS2/NiTiO3 was designed and synthesized by a simple hydrothermal method. The petal-like MoS2 is highly dispersive, which provides many active sites. The photocatalytic activity of MoS2/NiTiO3 for hydrogen evolution is better than that of pure MoS2 and NiTiO3 nanosheets. The hydrogen evolution amount of MoS2/NiTiO3 is 300.43 μmol, which is 5.3 and 1.9 times higher than of pure NiTiO3 and MoS2, respectively. In addition, the catalyst 7% MoS2/NiTiO3 has good stability through cyclic experiments. The results of photoluminescence spectroscopy and photoelectrochemical measurements show that the introduction of MoS2 accelerates the separation and transfer efficiency of photogenerated electrons. We have also proposed new discoveries for charge transfer mechanism of MoS2/NiTiO3 composite catalyst, which will provide a novel way to develop simple and inexpensive photocatalysts. [ABSTRACT FROM AUTHOR]

A Z-scheme heterojunction composite material Ni2P/RGO/MoO2 with high efficiency HER activity via a simple hydrothermal synthesis method which is one-step for photocatalytic H2 production was synthesized. The composite material which used reduced graphene oxide (RGO) as an electron transport medium and utilized a synergistic action of non-noble metal semiconductors Ni2P and MoO2 to construct Z-scheme heterojunction. Compared with the binary Ni2P/MoO2 composite photocatalyst, the photocatalytic hydrogen evolution activity of RGO assisted ternary composite Ni2P/RGO/MoO2 is significantly improved under visible light (λ > 420 nm) in the dye sensitization system in 5 h. The photocatalyst with optimal ratio reaches 355.34 μmol, which is about two times as much as the one without RGO. The transient photocurrent response, fluorescence test and hydroxyl radical capture experiment show that the type-II heterojunction originally composed of Ni2P and MoO2 is converted to Z-scheme in the presence of RGO. The transformation of the electron transfer mode effectively reduces the composite of photogenerated carriers. In addition, in situ hydrothermal synthesis allows Ni2P and MoO2 to be firmly modified on the RGO surface. This makes the composite photocatalyst exhibit great catalytic stability, and the HER activity of the photocatalyst hardly decrease in the four-cycle experiment. Through the one-step hydrothermal method, RGO assisted non-precious metal semiconductor composite provides a new idea for the synthesis of photocatalytic materials. The composite catalyst via the band gap regulation of MoO2 by Ni2P exhibits great hydrogen production activity in the dye-sensitized system. Subsequently, the GO solution was added during the synthesis to construct a Z-scheme heterojunction with graphene as an electron transporter. The ternary composite catalyst with a Z-scheme heterojunction shows approximately twice the hydrogen production rate of the binary catalyst. [ABSTRACT FROM AUTHOR]

The CoNi 2 S 4 /CdWO 4 -3 (CNS/CW-3) was an excellent photocatalyst for hydrogen evolution. The controlled morphology of CNS/CW-3 was successfully by adding thiourea as sulfur source and TBA to control the CoNi 2 S 4 nanoparticles. The photocatalytic hydrogen evolution activity of CoNi 2 S 4 and CdWO 4 under visible light irradiation was studied with different CoNi 2 S 4 incorporation ratios. UV–vis absorption spectra showed that the absorbance of CNS/CW-3 composite catalyst increased significantly after doping CoNi 2 S 4. The electrochemical and photoelectrochemical experiments also showed that the charge separation and electron transfer efficiency were higher when CoNi 2 S 4 was attached to CdWO 4. CNS/CW-3 exhibited excellent photocatalytic activity for hydrogen evolution under visible light irradiation. Its hydrogen evolution activity reached 269.08 μmol in 5 h, and had good light stability. It was a potential strategy to design photocatalyst with controllable morphology. The new composite material CoNi 2 S 4 /CdWO 4 has good photocatalytic activity and stability under visible light irradiation. UV–vis analysis showed that the band gap of the composite photocatalyst increased after hydrothermal recombination. In addition, under the regulation of TBA, CoNi 2 S 4 /CdWO 4 has a large specific surface area and pore volume, which is conducive to EY adsorption and electron transfer. The composite photocatalyst CoNi 2 S 4 /CdWO 4 with controllable flower globule has good application potential. Unlabelled Image • As a new kide of photocatalyst, it had a unique internal structure and good synergy, which greatly enhanced the photocatalytic activity of CuCo 2 S 4. • The electron transfer and charge separation were significantly improved by the uniform diffusion of CdWO 4 rod on the spherical CoNi 2 S 4 surface. • Bimetallic sulfides had a large specific surface area and provided more active sites to promote photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

Abstract The g-C 3 N 4 is an excellent photocatalyst for hydrogen evolution, but it is limited to only ultraviolet light by the wide band gap. In this work, the photocatalytic performance of g-C 3 N 4 was enhanced by loading of CeO 2 @Ni 4 S 3 cocatalyst. The XRD analysis result showed that CeO 2 @Ni 4 S 3 /g-C 3 N 4 was successfully synthesized by one-step hydrothermal method. UV–vis analysis shows that the visible light absorption range of photocatalyst becomes larger with the addition of CeO 2 @Ni 4 S 3. And the analysis results of PL and photo-electrochemical indicate that the electron transfer rate of the photocatalyst becomes faster with the addition of CeO 2 @Ni 4 S 3. The rate of hydrogen evolution of CeO 2 @Ni 4 S 3 /g-C 3 N 4 composite reaches to 3.74 mmol h−1 g−1 under visible light, it is 12 times that of pure g-C 3 N 4. And CeO 2 @Ni 4 S 3 /g-C 3 N 4 catalyst still has high photocatalytic activity after 4 cyclic reactions under visible light irradiation. Therefore, CeO 2 @Ni 4 S 3 /g-C 3 N 4 will be a potential excellent photocatalyst in the future. Graphical abstract The new composite CeO 2 @Ni 4 S 3 /g-C 3 N 4 exhibited excellent photocatalytic activity and photocatalytic stability under visible light irradiation. UV–vis analysis shows that the visible light absorption range of the composite becomes larger and its band gap decreases with the addition of CeO 2 @Ni 4 S 3. In addition, larger specific surface area and pore volume of CeO 2 @Ni 4 S 3 /g-C 3 N 4 are beneficial to adsorption of EY and transfer of electrons. fx1 Highlights • In this work, the new photocatalyst of CeO 2 @Ni 4 S 3 /g-C 3 N 4 was successfully synthesized by one-step hydrothermal method, and the visible light absorption range of photocatalyst becomes larger with the addition of CeO 2 @Ni 4 S 3. • The analysis results show that photocatalytic performance of g-C 3 N 4 was enhanced by loading of CeO 2 @Ni 4 S 3 cocatalyst. And the photo-electrochemical indicate that the electron transfer rate of the photocatalyst becomes faster with the addition of CeO 2 @Ni 4 S 3. • The rate of hydrogen evolution of CeO 2 @Ni 4 S 3 /g-C 3 N 4 composite reaches to 3.74 mmol h-1g-1 under visible light, it is 12 times that of pure g-C 3 N 4. And it still has high photocatalytic activity after 4 cyclic reactions under visible light irradiation. • Therefore, CeO 2 @Ni 4 S 3 /g-C 3 N 4 will be a potential excellent photocatalyst in the future. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO 2 to valuable multi-carbon products is an important potential solution to environmental and energy crises caused by fossil fuel burning. As an effective way to address the drawbacks of direct CO 2 reduction, the reduction of CO to multi-carbon products remains a challenge, specially lacking high-efficient, selective and low-cost metal-free catalysts. N-heterocyclic carbenes (NHCs) have been shown to be effective metal-free catalysts for converting CO 2 to CO or C 1 -products, but the facile release of CO limits the further reduction to valuable multi-carbon fuels. In this study, using density functional theory calculations, we developed heterogeneous NHCs by incorporating NHCs into the graphene lattice and found that these NHCs could stably adsorb and effectively activate CO molecules, enabling the efficient conversion of CO into CH 3 OH, C 2 H 4 and C 2 H 5 OH with low limiting potentials, i.e., –0.70, –0.45 and –0.36 V, respectively. These limiting potentials for C 2 -products are lower than those of most known metal-based or metal-free electrocatalysts. Moreover, competitive hydrogen evolution reaction can be effectively inhibited. The excellent catalytic performance is attributed to the charge transfer between NHCs and CO as well as the strong hybridization of C-2p orbitals of carbene carbon atoms in NHCs and carbon atoms in CO molecule. Our findings suggest that these heterogeneous NHCs exhibit high catalytic activity and selectivity for the conversion of CO to valuable C 2 -products. This study is the first report of NHC-based metal-free electrocatalysts for the conversion of CO to multi-carbon products, which will offer cost-effective opportunities for CO 2 reduction. [Display omitted] • This work presents a metal-free electrocatalyst with heterogeneous N-heterocyclic carbenes as the active centers. • The designed electrocatalyst exhibits high catalytic activity and selectivity for the conversion of CO to valuable C 2 -products. • This work is the first report of NHC-based metal-free electrocatalyst for the reduction of CO to multi-carbon products, opening a new and cost-effective method for CO 2 reduction. [ABSTRACT FROM AUTHOR]

NiCo-LDH with a layered structure was coupled to Mn 0.2 Cd 0.8 S through electrostatic self-assembly to construct tightly heterojunctioned photocatalysts. The bundles of stacked nanorods and the tightly packed sheets break the agglomeration of each other after electrostatic self-assembly, exposing more redox active sites. The introduction of NiCo-LDH further expands the light absorption of Mn 0.2 Cd 0.8 S towards the visible wavelength range, effectively improving the photoresponse performance. The charge density in NiCo-LDH increases after coupling and the transport direction of photogenerated carriers inside the photocatalyst follows the S-scheme heterojunction migration path. Photogenerated carriers are effectively separated, preserving the more redox-competent conduction band and valence band potentials. The reduction of charge transfer resistance and hydrogen evolution overpotential facilitated the hydrogen evolution reaction. Thus the optimised composite photocatalyst exhibits a significant improvement in hydrogen evolution performance (15.21 mmol·g−1h−1, approximately 28.17 times that of Mn 0.2 Cd 0.8 S) and maintained a good hydrogen evolution stability. [Display omitted] • Tight-contact NiCo-LDH/Mn 0.2 Cd 0.8 S photocatalyst was constructed through electrostatic self-assembly. • Charge transfer path following S-scheme heterojunction of NiCo-LDH/Mn 0.2 Cd 0.8 S is clarified. • Photocatalytic hydrogen evolution activity of NiCo-LDH/Mn 0.2 Cd 0.8 S reached 15.21 mmol·g−1·h−1. • 1D/2D interface enables fast migration of photogenerated carriers. [ABSTRACT FROM AUTHOR]