Stable CO2 Reduction under Natural Air on Ni-Sn Hydroxide Photocatalyst with Dynamic Renewable Oxygen Vacancies.

Advanced photocatalysts are highly desired to activate the photocatalytic CO2 reduction reaction (CO2RR) 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 (VO), thus beneficial to convert the activated CO2 (HCO3-) mainly into CO (5.60 μmol/g) 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 (1.58 μmol/g) and gas-solid (4.07 μmol/g) reaction system both using high pure CO2 and plenty of H2O. The strong hydrophilia by the rich surface hydroxyls allowed robust H2O molecule adsorption and dissociation at VO sites to achieve the Ni-OH regeneration, leading to a stable CO yield (11.61 μmol/g) with the enriched renewable VO regardless of the poor CO2 and H2O in air. This work opens up new possibilities for the practical application of natural photosynthesis.