Stable CO 2 reduction under natural air on Ni-Sn hydroxide photocatalyst with dynamic renewable oxygen vacancies.

Advanced photocatalysts are highly desired to activate the photocatalytic CO 2 reduction reaction (CO 2 RR) with low concentration. Herein, the NiSn(OH) 6 with rich surface lattice hydroxyls was synthesized to boost the activity directly under the natural air. Results showed that terminal Ni-OH could serve as donors to feed protons and generate oxygen vacancies (V O ), thus beneficial to convert the activated CO 2 (HCO 3 - ) mainly into CO (5.60 μ mol g -1 ) in the atmosphere. It was flexible and widely applicable for a stable CO 2 RR from high pure to air level free of additionally adding H 2 O reactant, and higher than the traditional gas-liquid-solid (1.58 μ mol g -1 ) and gas-solid (4.07 μ mol g -1 ) reaction system both using high pure CO 2 and plenty of H 2 O. The strong hydrophilia by the rich surface hydroxyls allowed robust H 2 O molecule adsorption and dissociation at V O sites to achieve the Ni-OH regeneration, leading to a stable CO yield (11.61 μ mol g -1 ) with the enriched renewable V O regardless of the poor CO 2 and H 2 O in air. This work opens up new possibilities for the practical application of natural photosynthesis.