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

Nitrogen fixation is the second most important chemical process in nature next to photosynthesis. Herein, we report a novel ternary metal sulfide photocatalyst Zn 0.1 Sn 0.1 Cd 0.8 S 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, SnS 2 and CdS. The sulfur vacancies on Zn 0.1 Sn 0.1 Cd 0.8 S not only serve as active sites to adsorb and activate N 2 molecules but also promote interfacial charge transfer from Zn 0.1 Sn 0.1 Cd 0.8 S to N 2 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. The NH 4 + generation rate over the as-prepared ternary metal sulfide catalysts is linearly related to the sulfur vacancy concentration, confirming that the photocatalytic reduction capacity of N 2 over ternary metal sulfides is highly dependent on the amount of sulfur vacancies.