Stable CO₂reduction under natural air on Ni-Sn hydroxide photocatalyst with dynamic renewable oxygen vacancies

Advanced photocatalysts are highly desired to activate the photocatalytic CO₂reduction reaction (CO₂RR) with low concentration. Herein, the NiSn(OH)₆with 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 CO₂(HCO₃^-) mainly into CO (5.60μmol g^-1) in the atmosphere. It was flexible and widely applicable for a stable CO₂RR from high pure to air level free of additionally adding H₂O reactant, and higher than the traditional gas-liquid-solid (1.58μmol g^-1) and gas-solid (4.07μmol g^-1) reaction system both using high pure CO₂and plenty of H₂O. The strong hydrophilia by the rich surface hydroxyls allowed robust H₂O molecule adsorption and dissociation at V_Osites to achieve the Ni-OH regeneration, leading to a stable CO yield (11.61μmol g^-1) with the enriched renewable V_Oregardless of the poor CO₂and H₂O in air. This work opens up new possibilities for the practical application of natural photosynthesis.