FeO–CeO2 nanocomposites: an efficient and highly selective catalyst system for photothermal CO2 reduction to CO
Jiaqing Zhao, Qi Yang, Run Shi, Geoffrey I. N. Waterhouse, Xin Zhang, Li‐Zhu Wu, Chen‐Ho Tung, Tierui Zhang
Abstract
Abstract Solar-driven catalysis is a promising strategy for transforming CO 2 into fuels and valuable chemical feedstocks, with current research focusing primarily on increasing CO 2 conversion efficiency and product selectivity. Herein, a series of FeO–CeO 2 nanocomposite catalysts were successfully prepared by H 2 reduction of Fe(OH) 3 -Ce(OH) 3 precursors at temperatures ( x ) ranging from 200 to 600 °C (the obtained catalysts are denoted as FeCe- x ). An FeCe-300 catalyst with an Fe:Ce molar ratio of 2:1 demonstrated outstanding performance for photothermal CO 2 conversion to CO in the presence of H 2 under Xe lamp irradiation (CO 2 conversion, 43.63%; CO selectivity, 99.87%; CO production rate, 19.61 mmol h −1 g cat −1 ; stable operation over 50 h). Characterization studies using powder X-ray diffraction and high-resolution transmission electron microscopy determined that the active catalyst comprises FeO and CeO 2 nanoparticles. The selectivity to CO of the FeCe- x catalysts decreased as the reduction temperature ( x ) increased in the range of 300–500 °C due to the appearance of metallic Fe 0 , which introduced an additional reaction pathway for the production of CH 4 . In situ diffuse reflectance infrared Fourier transform spectroscopy identified formate, bicarbonate and methanol as important reaction intermediates during light-driven CO 2 hydrogenation over the FeCe- x catalysts, providing key mechanistic information needed to explain the product distributions of CO 2 hydrogenation on the different catalysts.