Gas Transfer Highways Enhance the Hydrogen Evolution Reaction at Triple-Phase Boundaries.

Global demand for sustainable energy carriers has led to a growing interest in the hydrogen evolution reaction (HER), which produces an energy-dense and carbon-emission-free fuel. Despite notable advancements in the design of catalysts and membranes, HER production at high rates is still impeded by the removal of hydrogen gas bubbles, which leads to losses in energy efficiency. In this work, a nanoscale triple-phase boundary (TPB) of gas, liquid, and solid phases was prepared to study the limits of hydrogen removal from the catalyst/membrane interface. A robust atomic force microscopy (AFM) setup with a proton-conducting hydrogel was employed to study HER kinetics of single-entity Pt nanowires at the TPB. The TPB-based configuration allowed for the intrinsic activity of individual Pt catalysts to be quantified at current densities relevant to membrane electrolysis. Broadly, these findings provide a promising AFM-based model system for understanding electrocatalysis at TPBs and design of energy-efficient electrodes.