Photochemical conversion of CO2 into fuels has promise as a strategy for storage of intermittentsolar energy in the form of chemical bonds. However, higher-energy-value hydrocarbonsare rarely produced by this strategy, because of kinetic challenges. Here we demonstrate a strategy for green-light-driven synthesis of C1-C3 hydrocarbons from CO2 and H2O. In this approach, plasmonic excitation of Au nanoparticles produces a charge-rich environment at the nanoparticle/solution interface conducive for CO2 activation, while an ionic liquid stabilizes charged intermediates formed at this interface, facilitating multistep reduction and C-C coupling. Methane, ethylene, acetylene, propane, and propene are photosynthesized with a C2+ selectivity of ~50% under the most optimal conditions. Hydrocarbon turnover exhibits a volcano relationship as a function of the ionic liquid concentration, the kinetic analysis of which coupled with density functional theory simulationsprovides mechanis