Vacancy-enhanced photothermal activation for CO2 methanation on Ni/SrTiO3 catalysts

Photo-assisted thermocatalytic reduction of CO2 to CH4 has become a method used to alleviate the environmental crisis. In this study, Ni/SrTiO3-x catalysts enriched with oxygen vacancies were investigated to elucidate the role of these vacancies in photothermal CO2 methanation. The results show that Ni/SrTiO3-x catalysts have a higher concentration of oxygen vacancies and exhibit higher efficiency compared to Ni/SrTiO3 catalysts. The CO2 conversion reached 78 % under light conditions, which was about six times higher at 250 degrees C compared to the unlit state (14 %). First, the presence of oxygen vacancies enhances CO2 adsorption and activation. In addition, it leads to the formation of defective energy levels and improves light absorption. Meanwhile, the synergistic interaction of oxygen vacancies with Ni clusters promotes electron transfer. This study provides insights into the effect of oxygen vacancies on the methanation reaction under photothermal conditions, which guides the development of the field of CO2 reuse.