Reaction Mechanism of the Enhanced Reaction Activity and Rate of N-Doped CoO Photocatalysts for Photoreduction of CO₂ in Air

Abstract

The use of light to directly reduce CO2 in the atmosphere is the actual development trend of photocatalysis applications in the future. However, it is still in the initial stage of exploration. In this work, oleylamine is used as a template in a one-step hydrothermal method to obtain the N-doped CoO catalyst that can be used to efficiently reduce CO2 in air. N-doped CoO achieves ultrahigh CO2 conversion efficiency (about 75%), amazing CO yield (2.902 mmol g–1 h–1), and superior CO conversion frequency (TOFCO > 300) in air. However, in a 0.03% simulated atmosphere (Ar/CO2), the CO precipitation rate drops by 18 times, while the H2 precipitation rate increases significantly. Quasi-in situ spectroscopy and experimental studies show that O2 in the CO2 reduction process will promote the formation of an amorphous layer with a small number of hydroxyl groups on the surface of N-doped CoO. This amorphous/crystalline interface will effectively promote the catalytic reduction of CO2. This work has inspired further research on the photoreduction process of low-concentration CO2 in the future.