Abstract:
In view of their ability to absorb visible light and their high surface catalytic activity, metal sulfides are rapidly emerging as promising candidates for CO2 photoreduction, scoring over the traditional oxide-based systems. However, their low conversion efficiencies due to serious radiative recombination issues and poor stability restrict their real-life applicability. Enhancing their performance by coupling them with other semiconductor-based photocatalysts or precious noble metals as cocatalysts makes the process cost intensive. Herein, we report the single-phase ternary sulfide Cu3SnS4 (CTS) as a robust visible-light photocatalyst for selective photoreduction of CO2 to CH4. It showed a remarkable 80% selectivity for CH4 evolution with the rate of 14 μmol/g/h, without addition of any cocatalyst or scavenger. The mechanistic pathway for catalytic activity is elucidated by first principle calculations and in situ ATR, which imply a formaldehyde pathway of hydrocarbon production. The Cu–Sn termination of the surface is shown to be the key factor for competent CO2 absorption and activation as confirmed from our X-ray spectroscopy measurements and first principle calculations. This study provides a foundation and insights for the rational design of sulfide-based photocatalysts to produce renewable fuel.