Engineering Ultra-Small Nanochannel Electrocatalyst Towards the Improvement in Oxygen Evolution and Oxygen Reduction Reaction

The oxygen evolution (OER) and oxygen reduction reaction (ORR) offer a promising method of scalable energy storage and grid-scale power generation that could facilitate widespread adaptation of solar and wind power. However, the main challenge of these reactions is the sluggish kinetics, which caused by the scaling relation between adsorption energies of two reaction intermediates: *OH and *OOH species.¹ A theoretical study has proposed a scheme to circumvent these scaling relationships by defining a nanoscopic catalyst channel that capitalizes on different interactions between the intermediates and the catalyst owing to confinement.² However, such ultra-small nanochannel electrocatalyst has not been demonstrated experimentally.

Here in, we present a top-down nanofabrication scheme of nanoscopic electrocatalytic channels with tunable opening sizes from 10 nm to as small as 1 nm. The process utilizes standard nanofabrication techniques such as photolithography, atomic layer deposition, and ion-beam milling, and can be transferred to various catalyst systems. The performance of this proof-of-concept nanochannel electrocatalysts are investigated for the oxygen evolution and oxygen reduction reactions.

(1) Man, I. C.; Su, H.-Y.; Calle-Vallejo, F.; Hansen, H. A.; Martínez, J. I.; Inoglu, N. G.; Kitchin, J.; Jaramillo, T. F.; Nørskov, J. K.; Rossmeisl, J. ChemCatChem 2011, 3 (7), 1159-1165.

(2) Doyle, A. D.; Montoya, J. H.; Vojvodic, A. ChemCatChem 2015, 7 (5), 738-742.