Plasmonic systems convert light into electrical charges and heat that mediate catalytic transformations. However, the debate about the involvement of hot carriers in the catalytic process remains shredded in controversy. Here, we demonstrate the direct use of plasmon hot electrons in the hydrogen evolution with visible light. A plasmonic nanohybrid system consisting of NiO/Au/[CoII(phen-NH2)2(H2O)2] (phen-NH2 = 1,10-Phenanthrolin-5-amine) that is unstable at water thermolysis temperatures was consciously assembled, ensuring that the plasmon contribution to the catalytic process is solely from hot carriers. With the combination of photoelectrocatalysis and advanced in situ spectroscopies, one could establish the reaction mechanism, which consisted of electron injection into the phenanthroline-ligands followed by two quick, concerted proton-coupled electron transfer steps resulting in the evolution of hydrogen. Light-driven hydrogen evolution with plasmons provides a sustainable route for producing green hydrogen, which modern society strives to achieve.

Plasmonic systems effectively convert light into electrical charges and heat, which can mediate catalytic transformations. There are many examples of plasmonic photothermal catalytic reactions, but the involvement of hot carriers in the catalytic process remains a matter of intense debate and controversy. Here, we demonstrate the direct use of plasmon hot electrons in the photoelectrocatalytic CO2 reduction with visible light. A purposely assembled plasmonic nanohybrid system consisting of NiO/Au/ReI(phen-NH2)(CO)3Cl (phen-NH2 = 10-Phenanthrolin-5-amine) enabled direct access into hot-carrier-mediated reaction pathways by ultrafast spectroscopy, electrochemistry and catalytic testing. The ReI(phen-NH2)(CO)3Cl complex decomposes above 305°C, limiting thermal CO2 reduction contribution, making the plasmonic hot carriers the prime culprit for the process. Plasmonic light activation of CO2 provides a sustainable route for producing carbon fuels and feedstocks for society.