Photo-Assisted Catalytic CO2 Hydrogenation to CO with Nearly 100% Selectivity over Rh/TiO2 Catalysts

Photo-assisted catalytic CO2 hydrogenation represents a promising route to convert CO2 into value-added chemicals under mild conditions, but challenges remain in the design and development of highly active and selective catalysts. Herein, we synthesized highly efficient catalysts comprising Rh nanoparticles supported on TiO2 nanosheets for photo-assisted catalytic CO2 hydrogenation, which achieved a high CO production rate of 20.6 mmol gcat-1 h-1 (5.15 mol gRh-1 h-1) with nearly 100 % selectivity and excellent stability at 250 degrees C under light irradiation, outperforming most reported metal-based catalysts. X-ray photoelectron spectroscopy revealed that the electrons transfer from Rh nanoparticles to TiO2, hinting a strong interaction between Rh and the TiO2 support. Under illumination, the accumulated hot electrons on TiO2 surfaces could effectively promote the activation of CO2 molecules. In situ diffuse reflectance infrared Fourier transform spectroscopy results revealed that formate was the critical intermediate in the reverse water-gas shift reaction process, and light irradiation could effectively facilitate the activation and conversion of reactants and intermediate species, thereby improving CO production. This work provides a new strategy for the integration of solar and thermal energy for an efficient RWGS reaction under mild conditions.

Automated summary

In this study, highly efficient catalysts consisting of Rh nanoparticles supported on TiO2 nanosheets were synthesized for photo-assisted catalytic CO2 hydrogenation. The catalyst achieved a high CO production rate of 20.6 mmol gcat-1 h-1 (5.15 mol gRh-1 h-1) with nearly 100% selectivity and excellent stability under light irradiation at 250 degrees C, outperforming most reported metal-based catalysts. The integration of solar and thermal energy for an efficient reverse water-gas shift (RWGS) reaction under mild conditions is demonstrated.