Improved Charge Separation and CO₂ Affinity of In₂O₃ by K Doping with Accompanying Oxygen Vacancies for Boosted CO₂ Photoreduction

The CO2 photocatalytic conversion efficiency of the semiconductor photocatalyst is always inhibited by the sluggish charge transfer and undesirable CO2 affinity. In this work, we prepare a series of K-doped In2O3 catalysts with concomitant oxygen vacancies (O-V) via a hydrothermal method, followed by a low-temperature sintering treatment. Owing to the synergistic effect of K doping and O-V, the charge separation and CO2 affinity of In2O3 are synchronously promoted. Particularly, when P/P-0 = 0.010, at room temperature, the CO2 adsorption capacity of the optimal K-doped In2O3 (KIO-3) is 2336 cm(3)g(-1), reaching about 6000 times higher than that of In2O3 (0.39 cm(3)g(-1)). As a result, in the absence of a cocatalyst or sacrificial agent, KIO-3 exhibits a CO evolution rate of 3.97 mu molg(-1)h(-1) in a gas-solid reaction system, which is 7.6 times that of pristine In2O3 (0.52 mu molg(-1)h(-1)). This study provides a novel approach to the design and development of efficient photocatalysts for CO2 conversion by element doping.