Sn2+ and Cu2+ Self-Codoped Cu2ZnSnS4 Nanosheets Switching from p-Type to n-Type Semiconductors for Visible-Light-Driven CO2 Reduction

ABSTRACT: Energy level engineering is a powerful technique to tune the electron transport and the photocatalytic properties of photocatalysts with low-valence Sn2+ and high-valence Cu2+ selfcodoping by solvothermal method. The band gap energy level and Fermi level of Cu2ZnSnS4 nanosheets can be adjusted by controlling Sn2+ and Cu2+ self-codoping at different solvothermal temperature. This leads to semiconductor behavior change from p-type of the intrinsic Cu2ZnSnS4 to the n-type of self-codoped sample. The n-type Cu2ZnSnS4 nanosheets exhibit a good CO2 photoreduction performance to yield 48.14 and 25.04 mu mol g-1 h-1 of CO and CH4, where CO yields on n-type Cu2ZnSnS4 is about 4 times higher than that on the intrinsic Cu2ZnSnS4. This work offers a versatile approach of different valence metal ion self-codoping to engineer the energy level of multimetal semiconductor photocatalyst.