Junchuan Sun, Rui Song, Chang Xu, Xue Ding, Wanguo Gao, Athanasios A Tountas, Zhe Lu, Jiakun Wang, Zeshu Zhang, Xiaolu Zhuo, Yingfang Yao, Zhigang Zou, Geoffrey A Ozin, Lu Wang
Unlike the well-known charge-carrier kinetics in traditional photocatalysis, a knowledge gap remains regarding the photo-kinetic effects in heterogeneous photothermal catalysis. Conventionally, light is mainly regarded as a source of charge carriers and localized heating, yet how these light-induced effects alter intrinsic reaction kinetics, particularly the rate-determining step (RDS), remains unclear. Here, we provide direct kinetic evidence that illumination tunes the RDS in an archetypal Mars-van Krevelen (MvK) reverse water-gas shift (RWGS) reaction over In-doped MoO2. Under illumination, photogenerated electrons enrich In sites, promoting H2 activation and spillover while accelerating H2O desorption, thereby shifting the RDS from the H2-reduction half-reaction to the CO2-oxidation half-reaction. This kinetic modulation significantly enhances catalytic performance and lowers the apparent activation energy. Overall, this work elucidates the kinetic role of light in photothermal CO2 conversion, offering new insights into optimizing solar-driven catalytic processes.