Light-Driven Syngas Production over Defective ZnIn2 S4 Nanosheets.

Photocatalytic syngas (CO and H2 ) production with CO2 as gas source not only ameliorates greenhouse effect, but also produces valuable chemical feedstocks. However, traditional photocatalytic systems require noble metal or suffers from low yield. Here, we demonstrate that S vacancies ZnIn2 S4 (VS -ZnIn2 S4 ) nanosheets are an ideal photocatalyst to drive CO2 reduction into syngas. It is found that building S vacancies can endow ZnIn2 S4 with stronger photoabsorption, efficient electron-hole separation, and larger CO2 adsorption, finally promoting both hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2 RR). The syngas yield of CO and H2 is therefore significantly increased. In contrast to pristine ZnIn2 S4 , the syngas yield over VS -ZnIn2 S4 can be improved by roughly ≈4.73 times and the CO/H2 ratio is modified from 1:4.18 to 1:1. Total amount of syngas after 12 h photocatalysis is as high as 63.20 mmol g-1 without use of any noble metals, which is even higher than those of traditional noble metal-based catalysts in the reported literatures. This work demonstrates the critical role of S vacancies in mediating catalytic activity and selectivity, and highlights the attractive ability of defective ZnIn2 S4 for light-driven syngas production.