Experimental and theoretical insights into an enhanced CO2 methanation mechanism over a Ru-based catalyst

Converting excessive CO2 emissions from industrial operation into methane (CH4) is critical for the remediation of global warming. However, this reaction requires a high temperature to overcome the high thermodynamic stability of CO2. The development of efficient catalysts for the CO2 methanation reaction at low temperature remains challenging. Here we report that when a TiO2 photothermal catalyst is loaded with Ru nanoparticles, the CO2 to CH4 conversion efficiency is markedly enhanced under light illumination. In fact, the CO2 performance was enhanced fourfold and twofold from those of the traditional thermal catalytic reaction at 200 ? and 250 ?, respectively. In-situ DRIFTS analysis revealed that light irradiation accelerates the transition of bicarbonate to formates via light-induced charge carriers. Moreover, theoretical calculations revealed that photo-induced electron transfer effectively promotes H-2 dissociation and CO2 activation on the Ru atoms. This work provides new theoretical insights into CO2 activation and methanation under light illumination.