Photochemical H 2 dissociation for nearly quantitative CO 2 reduction to ethylene

Producing olefins by carbon dioxide (CO 2 ) hydrogenation is a long-standing goal. The usual products are multicarbon mixtures because the critical step of heterolytic hydrogen (H 2 ) dissociation at high temperatures complicates selectivity control. In this study, we report that irradiating gold–titanium dioxide at 365 nanometers induces heterolytic H 2 dissociation at ambient temperature. This process likely relies on interfacial electric dipoles from photogenerated electrons and holes situated on the metallic gold nanoparticles and interfacial gold–oxygen–titanium scaffolds. The heterolytic H 2 dissociation is further promoted by light-induced coating of gold nanoparticles with a titanium oxide layer. The resulting nucleophilic hydrogen species reduce CO 2 to ethane in >99% yield under light irradiation in a flow apparatus. Furthermore, cascading with a subsequent photocatalytic ethane dehydrogenation generates ethylene in >99% yield over 1500 hours of irradiation.