Controllable design of double metal oxide (NiCo 2 O 4 )-modified CdS for efficient photocatalytic hydrogen production.

In the present study, we have successfully synthesized a kind of high-efficiency NiCo2O4/CdS composite photocatalyst using the hydrothermal method and high-temperature calcination. With the addition of NiCo2O4, hydrogen evolution has been significantly improved by successfully adjusting the electron transport routes. For the composite catalyst, the maximum amount of hydrogen evolution under visible light irradiation for 5 hours reached 549 μmol. Through this phenomenon, the hydrogen production rate of the corresponding composite catalysts reached 10 980 μmol g-1 h-1. The hydrogen production rate of the composite catalysts is 5.1 times that of pure CdS under the same conditions. In addition, there was no significant decrease in the photocatalytic activity of the composite catalyst even after 5 cycles of photocatalytic hydrogen production. These phenomena indicate that the introduction of NiCo2O4 inhibits the photo-corrosion of CdS itself and enhances hydrogen production activity while ensuring the stability of the catalyst. In order to characterize the physical properties of the NiCo2O4/CdS composite catalyst, we used XRD, SEM, TEM, XPS, BET and UV-vis techniques. In photoelectron and hole transport mechanisms, we have studied the catalysts by photoluminescence spectroscopy, transient photocurrent and photoelectrochemical experiments. The introduction of NiCo2O4 increases the active site of the composite catalyst, which facilitates the separation of photogenerated electrons and holes and accelerates the transfer of electrons.