The photoexcitation of plasmonic nanoparticles has been shown to drive multistep, multicarrier transformations, such as the conversion of CO2 into hydrocarbons. But for such plasmon-driven chemistry to be precisely understood and modeled, the critical photoinitiation step in the reaction cascade must be identified. We meet this goal by measuring H/D and 12C/13C kinetic isotope effects (KIEs) in plasmonic photosynthesis. In particular, we found that the substitution of H2O with D2O slows hydrocarbon production by a factor of 5–8. This primary H/D KIE leads to the inference that hole-driven scission of the O−H bond in H2O is a critical, limiting step in plasmonic photosynthesis. This study advances mechanistic understanding of light-driven chemical reactions on plasmonic nanoparticles.
Funding for this work was provided by the Energy & Biosciences Institute (EBI) through the EBI‐Shell program. We thank Varun Mohan, who compared pH and pD values of EMIM–BF. 4Funding for this work was provided by the Energy & Biosciences Institute (EBI) through the EBI-Shell program. We thank Varun Mohan, who compared pH and pD values of EMIM–BF4.
