Creation of SnxNb1−xO2 solid solution through heavy Nb-doping in SnO2 to boost its photocatalytic CO2 reduction to C2+ products under simulated solar illumination

Abstract Photocatalytic CO 2 reduction driven by green solar energy could be a promising approach for the carbon neutral practice. In this work, a novel defect engineering approach was developed to form the Sn x Nb 1− x O 2 solid solution by the heavy substitutional Nb-doping of SnO 2 through a robust hydrothermal process. The detailed analysis demonstrated that the heavy substitution of Sn 4+ by a higher valence Nb 5+ created a more suitable band structure, a better photogenerated charge carrier separation and transfer, and stronger CO 2 adsorption due to the presence of abundant acid centers and excess electrons on its surface. Thus, the Sn x Nb 1− x O 2 solid solution sample demonstrated a much better photocatalytic CO 2 reduction performance compared to the pristine SnO 2 sample without the need for sacrificial agent. Its photocatalytic CO 2 reduction efficiency reached ∼292.47 µmol/(g·h), which was 19 times that of the pristine SnO 2 sample. Furthermore, its main photocatalytic CO 2 reduction product was a more preferred multi-carbon (C 2+ ) compound of C 2 H 5 OH, while that of the pristine SnO 2 sample was a one-carbon (C 1 ) compound of CH 3 OH. This work demonstrated that, the heavy doping of high valence cations in metal oxides to form solid solution may enhance the photocatalytic CO 2 reduction and modulate its reduction process, to produce more C 2+ products. This material design strategy could be readily applied to various material systems for the exploration of high-performance photocatalysts for the solar-driven CO 2 reduction.

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