The photoelectric effect at the metal-electrolyte interface leads to the emission of electrons into the solution, creating solvated electrons. These powerful reducing agents, capable of reducing CO<sub>2</sub> and hydrocarbons, enable new opportunities for electrocatalysis by no longer restricting the reaction to the electrode surface. However, electron photoemission has attracted little attention due to low quantum efficiencies. Previous work has demonstrated that photoemission yield is enhanced by employing nanostructured electrodes, however, the enhancement mechanism has remained unknown. In this work, we quantitatively determine that electron photoemission into water is increased by electric field enhancement on the surface of nanoparticles. We measure hydrated electron-induced photocurrents from different smooth and nanostructured metal electrodes to spectrally resolve the photoemission enhancement and find a ten-times enhancement in quantum yield when using nanostructured metal electrodes. Simulations of the electric field on the electrode surfaces using finite-difference time-domain method reveal that the photoemission-enhancement spectra follow electric field enhancement and not absorption spectra. Our results, therefore, suggest that quantum yields can be maximized by optimizing the electric field of the electrode. This work shows that plasmonic nanoparticles can be used to drive homogenous photoelectrochemical catalysis, opening up new catalytic pathways.

Electric field enhancement increases photoemission of hydrated electrons

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.