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.
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