Photo-accelerated water dissociation across one-atom-thick electrodes

TL;DR

This study demonstrates that visible-light illumination significantly accelerates water dissociation at graphene electrodes, revealing new insights into ion dynamics and potential applications in photo-catalysis and reconfigurable materials.

Contribution

It uncovers a photo-induced acceleration of water dissociation on atomically-thin graphene, combining the Wien effect with proton selectivity for enhanced ionic processes.

Findings

Order-of-magnitude increase in water dissociation rate under light

Proton separation across graphene prevents recombination

Enhanced ion transport due to interfacial electric fields

Abstract

Recent experiments demonstrated that interfacial water dissociation (H2O = H+ + OH-) could be accelerated exponentially by an electric field applied to graphene electrodes, a phenomenon related to the Wien effect. Here we report an order-of-magnitude acceleration of the interfacial water dissociation reaction under visible-light illumination. This process is accompanied by spatial separation of protons and hydroxide ions across one-atom-thick graphene and enhanced by strong interfacial electric fields. The found photo-effect is attributed to the combination of graphene's perfect selectivity with respect to protons, which prevents proton-hydroxide recombination, and to proton transport acceleration by the Wien effect, which occurs in synchrony with the water dissociation reaction. Our findings provide fundamental insights into ion dynamics near atomically-thin proton-selective interfaces and suggest that strong interfacial fields can enhance and tune very fast ionic processes, which is of relevance for applications in photo-catalysis and designing reconfigurable materials.