Preparation of p-n heterojunction with NiWO4 and Co-based bimetallic oxide and its photocatalytic hydrogen evolution performance

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.