Hot-electron-induced CO2 hydrogenation on Au@AuRu/g-C3N4 plasmonic bimetal–semiconductor heterostructure

Abstract

Hot-electron-induced CO2 hydrogenation is a promising pathway for solar-to-chemical energy conversion under mild conditions. Herein, we designed a unique “antenna–reactor” architecture with surface alloyed Au@AuRu plasmonic nanoparticles (NPs) loaded on g-C3N4 (Au@AuRu/g-C3N4) to achieve high-efficiency CO2 methanation under light-heat dual activation. Remarkably, Au@AuRu/g-C3N4 exhibits a high CH4 production rate (103 μmol/g/h) with 98.4% selectivity under light at 150 °C. The activity is 11 times higher than that in dark, and also 12 and 2.6 times that of Au/g-C3N4 and Au@Ru/g-C3N4, respectively. The modified Ru atoms significantly boost the H2, CO2 and CO adsorption capacity, facilitating the selective transformation of CO2 to CH4. In situ DRIFT analysis indicated that CO2 is converted to CO and then adsorbed on the metal surface for further hydrogenation to CH4. The femtosecond transient absorption spectroscopic study further reveals that the synergy between the surface structure and the metal–semiconductor heterojunction provides a longer time window for hot electrons to promote the chemical reaction. This work provides new insights for plasmonic nanostructures to efficiently activate CO2 at low temperatures.