Cobalt Promotion of the InOx -TiO2 Heterojunction for Dual Photothermal Reduction of CO2

Abstract

A series of cobalt-promoted indium-titanium composite oxides was synthesized using a microemulsion method. Their functional properties were investigated for the photothermal reduction of carbon dioxide. In this series, the indium content varied between 2.5 and 20%, while the cobalt percentage was kept constant at 4% throughout the series. In all cases, carbon monoxide formation occurred selectively through the reverse water gas shift reaction. The sample with a 2.5% maximized the synergistic use of the two energy sources, while the sample with 10% showed the highest catalytic activity at both thermal and dual photo-thermo conditions. A physicochemical characterization was performed for all samples. The use of microscopy and X-ray absorption spectroscopy demonstrated that sub-nanometric indium entities, in combination with atomically dispersed cobalt oxide entities, achieved a balance between high thermal activity and significant synergy between light and heat in a catalytic process. The system with 10 % indium is thus able to improve the thermal catalytic process through the use of light, providing an intensification procedure for the classic process.