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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]

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]