Sensitivity of Gas-Evolving Electrocatalysis to the Catalyst Microenvironment

Manyelectrochemical reactions for the development of renewableenergy technologies are gas-evolving reactions, where the electrocatalyticperformance is susceptible to the wetting properties of the catalystmicroenvironment. Here, using N2H4 electro-oxidationto N-2 on carbon-supported Pt nanocatalysts as a model reaction,we controlled the microenvironment using oxygen-doped and fluorine-dopedcarbon supports to make it more hydrophilic and more hydrophobic,respectively, and elucidated the effect on the reaction kinetics.The electrode with oxygen-doped carbon showed a 123% higher activitythan that with pristine carbon, benefiting from the increased wettingand exposure of Pt catalytic sites to the electrolyte. Counterintuitively,the electrode with fluorine-doped carbon also exhibited a 46% higheractivity than that with pristine carbon, despite its lower wettingof Pt. We found that the hydrophobic microenvironment acceleratedthe surface diffusion, coalescence, and detachment of the generatedN(2) gas bubbles, which would otherwise block the Pt activesites from catalyzing the reaction.

Automated summary

The wetting properties of the catalyst microenvironment have a significant impact on the electrocatalytic performance of gas-evolving reactions. By controlling the microenvironment using oxygen-doped and fluorine-doped carbon supports, the activity of carbon-supported Pt nanocatalysts for N2H4 electro-oxidation was increased by 123% and 46% respectively.