Photo-depositing ruthenium species on defect-rich strontium titanate enhances photothermal catalytic dry reforming of methane through light-induced charge transfer and oxygen migration

Abstract

Photothermal catalytic dry reforming of methane (DRM) has emerged as a promising approach to lower activation energy and prevent catalyst sintering and coking, garnering widespread interest. In this study, we developed a photo-induced reduction method to mediate Ru species onto defect-rich strontium titanate (SrTiO_3-x), resulting in photothermal catalytic activity. The catalyst performed production rates of 306.4 mmol·g_cat⁻¹·h⁻¹ for CO and 236.1 mmol·g_cat⁻¹·h⁻¹ for H₂ at 400 °C under 3.21 W·cm⁻² light intensity in a flow reactor, with remarkable light-to-chemical energy efficiency (LTCEE) of 7.41 %. Experimental characterizations and theoretical simulations revealed that the interfacial contact between Ru and SrTiO_3-x significantly enhanced photogenerated electrons transfer and gather on Ru, facilitating the adsorption and C − H bond cleavage of CH₄. Additionally, surface oxygen vacancies, the light-induced metal-to-metal charge transfer (MMCT) process and high oxygen mobility synergistically promoted the cleavage of C=O bonds and the elimination of carbon species. Consequently, the activation energy barrier was significantly lower, enhancing the conversion efficiency and selectivity of DRM under lower reaction temperatures. This work provides valuable insights into a straightforward approach for designing efficient noble-metal-supported photothermal DRM catalysts.