Highly efficient hydrogen production performance of g-C 3 N 4 quantum dot-sensitized WO 3 /Ni–ZnIn 2 S 4 nanosheets

Metal sulfide semiconductor photocatalysts have been widely used in photocatalytic hydrogen evolution reactions due to their good light absorption properties and high photostability. However, the metal sulfide photogenerated carriers of these catalysts are susceptible to recombination, which reduces the rate of hydrogen production. In this study, ZnIn 2 S 4 was doped with the transition metal ion Ni 2+ to regulate and control the absorption sidebands of ZnIn 2 S 4 , improve the catalyst's responsiveness to visible light, and hence increase the hydrogen production rate. Ni–ZnIn 2 S 4 catalysts with varying doping ratios were prepared, and the optimal doping ratio of 1.0% was selected for further experiments. A WO 3 /Ni–ZnIn 2 S 4 composite photocatalyst was synthesized using the hydrothermal method to produce a heterojunction with a constant doping ratio of 1.0%. Loading WO 3 on this catalyst enhanced the light absorption intensity, improved the photogenerated carrier separation efficiency, and significantly increased the hydrogen evolution rate of the catalyst by 2.1 times. Finally, an g-C 3 N 4 QDs/WO 3 /Ni–ZnIn 2 S 4 catalyst was prepared by loading quantum dots for sensitization. The g-C 3 N 4 quantum dots served as a sensitizing role, greatly improved the light absorption intensity, and further improved the hydrogen evolution rate of the catalyst, which was increased to 9.29 mmol/(g·h).