Hydrolysis-Induced InOx on ZnIn2S4 Promotes Selective CO2 Photoreduction over H2 Evolution

Metal sulfides generally show high visible light photocatalytic activity, but lower selectivity in the CO2 photoreduction due to the competitive hydrogen evolution. Here, a partial hydrolysis method is reported to promote the selective photocatalytic CO2 reduction over ZnIn2S4. The ZnIn2S4 was post-hydrolyzed in an aqueous ammonia solution to form oxide species (ZIS-[InOx]). Detailed experiment and DFT calculation demonstrated that the post-hydrolysis treatment facilely prohibits the recombination of photogenerated charge carriers and benefits CO2 activation. Under visible light irradiation, the ZIS-[InOx] photocatalyst shows enhanced CO2-to-CO conversion activity with a CO-evolving rate of 1771 mu mol g(-1) h(-1), which is about 8 times higher than that over pristine ZIS and 3.5 times higher than that over bulk ZIS/In2O3. More importantly, the post hydrolysis treatment significantly prohibits the hydrogen evolution and increases the CO/H-2 ratio from 0.08 over ZIS to 1.8 over ZIS-[InOx]. This work provides a new strategy to prepare catalysts for photocatalytic CO2 reduction.