Non-Metal Sulfur Doping of Indium Hydroxide Nanocube for Selectively Photocatalytic Reduction of CO2 to CH4: A “One Stone Three Birds” Strategy

Photocatalytic CO 2 reduction is considered as a promising strategy for CO 2 utilization and producing renewable energy, however, it remains challenge in the improvement of photocatalytic performance for wide-band-gap photocatalyst with controllable product selectivity. Herein, the sulfur-doped In(OH) 3 (In(OH) x S y -z) nanocubes are developed for selective photocatalytic reduction of CO 2 to CH 4 under simulated light irradiation. The CH 4 yield of the optimal In(OH) x S y -1.0 can be enhanced up to 39 times and the CH 4 selectivity can be regulated as high as 80.75% compared to that of pristine In(OH) 3 . The substitution of sulfur atoms for hydroxyl groups in In(OH) 3 enhances the visible light absorption capability, and further improves the hydrophilicity behavior, which promotes the H 2 O dissociation into protons (H * ) and accelerates the dynamic proton-feeding CO 2 hydrogenation. In situ DRIFTs and DFT calculation confirm that the non-metal sulfur sites significantly weaken the over-potential of the H 2 O oxidation and prevent the formation of ·OH radicals, enabling the stabilization of * CHO intermediates and thus facilitating CH 4 production. This work highlights the promotion effect of the non-metal doping engineering on wide-band-gap photocatalysts for tailoring the product selectivity in photocatalytic CO 2 reduction.