Ultrathin Nickel-doped ZnIn2S4 Nanosheets with Sulfur Vacancies for Efficient Photocatalytic Hydrogen Evolution

Graphical Sulfur vacancies and nickel dopants were simultaneously introduced into ultrathin ZnIn 2 S 4 nanosheets (ZIS NSs) to boost photocatalytic hydrogen evolution. Ni 0.05 −V S −ZIS reaches the highest photocatalytic hydrogen evolution rate of 8.91 mmol g −1 h −1 under visible light irradiation. The synergistic role of S vacancies and Ni dopants allows the photoexcited electrons in the CB to transfer to the trap state, thus delaying the recombination of photogenerated electrons and holes. Introducing vacancies and element doping are effective approaches to boost photocatalytic activities of metal sulfides. In this work, sulfur vacancies and nickel dopants were simultaneously introduced into ultrathin ZnIn 2 S 4 nanosheets (ZIS NSs) to explore their synergistic role in promoting photocatalytic hydrogen evolution. The S vacancies can trap the photo-generated electrons, lower the conduction band minimum (CBM), improve the photo-generated charge reduction capacity and prolong the carrier lifetime. Meanwhile, Ni dopants cause an increase in the Fermi level (E F ), which ensures a higher charge density and an effective carrier separation efficiency. The optimum hydrogen evolution rate of sample Ni 0.05 −V S −ZIS reaches 8.91 mmol g −1 h −1 under visible light due to the synergistic effect of the S vacancies and Ni dopants.