Cost-effective and dynamic carbon dioxide conversion into methane using a CaTiO₃@Ni-Pt catalyst in a photo-thermal hybrid system

This research focuses on the synergy of converting carbon dioxide (CO₂) into methane (CH₄) by simultaneously introducing light and heat as dynamic sources to activate the catalyst. A CaTiO₃@Ni-Pt catalyst, loaded with 30.0 wt.% Ni and 1.0 wt.% Pt on a perovskite CaTiO₃ support was introduced. The photo-thermal catalytic hybrid system has two features that distinguish it from other photo- or thermal-catalytic systems. First, unlike the CO₂ thermal-methanation reaction where CO₂ and H₂ react at a molar ratio of 1:4, 2.0 mol of H₂ was replaced with 2.0 mol H₂O in the photo-thermal catalytic hybrid system compared to the thermal-methanation reaction requiring 4.0 mol of H₂. Second, by loading Ni and Pt, which are catalytic active species with excellent CO₂ and H₂ adsorption abilities, the CO₂ reduction (46.48%) was promoted and the CH₄ selectivity (99.46%) in the product was increased compared to the photo-methanation reaction. The CaTiO₃@Ni-Pt not only inhibited the recombination of the photo-generated charges, but also facilitated the adsorption of the reactants in the photo-thermal hybrid system. The quantum efficiency of the CaTiO₃@Ni-Pt catalyst measured for the photo-thermal hybrid system steadily increased to 180 °C. Nevertheless, this study implies that a photo-thermal hybrid system can be useful to photo-reducing CO₂ by adding a small amount of heat. From a thermal reaction standpoint, a photo-thermal hybrid system can be used to reduce the reaction temperature during CO₂ thermal-methanation and to reduce the consumption of H₂ in half.