Facile fabrication of SnO2 modified hierarchical BiOI S-scheme heterojunction photocatalyst with efficient activity for carbon dioxide reduction

The use of photocatalysts on semiconductor substrates is a promising strategy for multiple use of solar energy and environmental improvement to convert CO2 to CH3OH. In this paper, a series of SnO2-modified BiOI (SnO2/BiOI) novel s-scheme heterojunction microsphere catalysts were synthesized, and the effect of temperature on the photocatalytic CO2 reduction reactivity of SnO2 grown on pure BiOI surface was systematically investigated by adjusting the calcination reaction temperature. Among all SnO2/BiOI composite photocatalytic systems, the highest CH3OH yield (1183 μmol/gcat, 4 h) was achieved when SnO2/BiOI was synthesized at 400 °C, which was 2.7 times higher than that of BiOI alone (437 μmol/gcat, 4 h). The SnO2/BiOI microspheres with s-scheme heterojunction exhibited surprising photocatalytic performance for CH3OH formation due to the formation of an internal eletricfield between SnO2 and BiOI also facilitated the separation of the photogenerated electron-hole pairs.