Water-Mediated Selectivity Control of CH3OH versus CO/CH4 in CO2 Photoreduction on Single-Atom Implanted Nanotube Arrays

Controllable methanol production in artificial photosynthesis is highly desirable due to its high energy density and ease of storage. Herein, single atom Fe is implanted into TiO2/SrTiO3 (TSr) nanotube arrays by two-step anodization and Sr-induced crystallization. The resulting Fe-TSr with both single Fe reduction centers and dominant oxidation facets (001) contributes to efficient CO2 photoreduction and water oxidation for controlled production of CH3OH and CO/CH4. The methanol yield can reach to 154.20 mu mol g(cat)(-1) h(-1) with 98.90% selectivity by immersing all the catalyst in pure water, and the yield of CO/CH4 is 147.48 mu mol g(cat)(-1) h(-1) with >99.99% selectivity when the catalyst completely outside water. This CH3OH yield is 50 and 3 times higher than that of TiO2 and TSr and stands among all the state-of-the-art catalysts. The facile gas-solid and gas-liquid-solid phase switch can selectively control CH3OH production from approximate to 0% (above H2O) to 98.90% (in H2O) via slowly immersing the catalyst into water, where abundant center dot OH and H2O around Fe sites play important role in selective CH3OH production. This work highlights a new insight for water-mediated CO2 photoreduction to controllably produce CH3OH.