Boosting photo-thermal co-catalysis CO₂ methanation by tuning interface electron transfer via Mott-Schottky heterojunction effect

Photo-thermal co-catalytic reduction of CO₂ to synthesize value-added chemicals presents a promising approach to addressing environmental issues. Nevertheless, traditional catalysts exhibit low light utilization efficiency, leading to the generation of a reduced number of electron-hole pairs and rapid recombination, thereby limiting catalytic performance enhancement. Herein, a Mott-Schottky heterojunction catalyst was developed by incorporating nitrogen-doped carbon coated TiO₂ supported nickel (Ni) nanometallic particles (Ni/x-TiO₂@NC). The optimal Ni/0.5-TiO₂@NC sample displayed a conversion rate of 71.6 % and a methane (CH₄) production rate of 65.3 mmol/(g_cat·h) during photo-thermal co-catalytic CO₂ methanation under full-spectrum illumination, with a CH₄ selectivity exceeding 99.6 %. The catalyst demonstrates good stability as it shows no decay after two reaction cycles. The Mott-Schottky heterojunction catalysts display excellent efficiency in separating photo-generated electron-hole pairs and elevate the catalysts' temperature, thus accelerating the reaction rate. The in-situ experiments revealed that light-induced electron transfer effectively facilitates H₂ dissociation and enhances surface defects, thereby promoting CO₂ adsorption. This study introduces a novel approach for developing photo-thermal catalysts for CO₂ reduction, aiming to enhance solar energy utilization and facilitate interface electron transfer.