Transient Temperature Response of Supported Rh Nanoparticles in Photothermal Dry Reforming of Methane-An Operando Dispersive X-ray Absorption Spectroscopy Study

Photothermal catalytic conversion of CO2 is an effective strategy for solar energy storage and CO2 utilization. The selective heating of metal nanoparticles (NPs) endows the high temperature reaction field for CO(2 )conversion; however, temperatures at the nanoscale under photothermal reaction conditions remain unrevealed. In this study, we performed operando dispersive X-ray absorption spectroscopy (DXAS) under concentrated visible and near-infrared light to evaluate the temperature of the catalytic active sites of Rh NPs on Al2O3 (local temperature) in the photothermal dry reforming of methane. The millisecond-order DXAS measurements demonstrated that the transient change in the local temperature of Rh NPs was affected by the formation process of the surface carbon-containing intermediates. The analysis methodology using operando time-resolved DXAS opens temperature evaluation at the nanoscale under light irradiation, including sunlight.