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

Abstract This research focuses on the synergy of converting carbon dioxide (CO 2 ) into methane (CH 4 ) by simultaneously introducing light and heat as dynamic sources to activate the catalyst. A CaTiO 3 @Ni-Pt catalyst, loaded with 30.0 wt.% Ni and 1.0 wt.% Pt on a perovskite CaTiO 3 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 CO 2 thermal-methanation reaction where CO 2 and H 2 react at a molar ratio of 1:4, 2.0 mol of H 2 was replaced with 2.0 mol H 2 O in the photo-thermal catalytic hybrid system compared to the thermal-methanation reaction requiring 4.0 mol of H 2 . Second, by loading Ni and Pt, which are catalytic active species with excellent CO 2 and H 2 adsorption abilities, the CO 2 reduction (46.48%) was promoted and the CH 4 selectivity (99.46%) in the product was increased compared to the photo-methanation reaction. The CaTiO 3 @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 CaTiO 3 @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 CO 2 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 CO 2 thermal-methanation and to reduce the consumption of H 2 in half.