Effect of sulfur vacancies on the nitrogen photofixation performance of ternary metal sulfide photocatalysts

Abstract

Nitrogen fixation is the second most important chemical process in nature next to photosynthesis. Herein, we report a novel ternary metal sulfide photocatalyst Zn_0.1Sn_0.1Cd_0.8S with outstanding nitrogen photofixation ability under visible light. Characterization results indicate that the actual atomic ratio of the as-prepared ternary metal sulfide is Zn : Sn : Cd : S of 0.11 : 0.12 : 0.88 : 1.12 with many sulfur vacancies, not a mixture of ZnS, SnS₂ and CdS. The sulfur vacancies on Zn_0.1Sn_0.1Cd_0.8S not only serve as active sites to adsorb and activate N₂ molecules but also promote interfacial charge transfer from Zn_0.1Sn_0.1Cd_0.8S to N₂ molecules, thus significantly improving the nitrogen photofixation ability. The other three as-prepared ternary metal sulfides with sulfur vacancies fabricated via the same method exhibit nitrogen photofixation ability, confirming the significantly important role of sulfur vacancies in the nitrogen photofixation process.