Enhancing Hydrogen Evolution Reaction through Coalescence-Induced Bubble Departure on Patterned Gold-Silicon Microstrip Surfaces.

Hydrogen bubble adhesion to the electrode presents a major obstacle for green hydrogen generation via the hydrogen evolution reaction (HER) as it would induce undesired overpotential and undermine the reaction efficiency by reducing reaction area, increasing transport resistance, and creating an undesired ion concentration gradient. While electrodes with aerophobic/hydrophilic surfaces have been developed to facilitate bubble detachment, they primarily rely on micro- and nanostructured catalyst surfaces to enhance buoyance-induced bubble departure. Here, we demonstrate that introducing nonreactive yet more hydrophilic surfaces can promote coalescence-induced bubble departure, thereby significantly reducing the transport overpotential and improving HER performance. Through a systematic study using patterned gold-silicon microstrip (GSM) surfaces with varied gold strip widths (50-1600 μm), we found that reducing the gold strip width results in a smaller bubble departure diameter and increased bubble departure frequencies, leading to a 400 mV reduction in transport overpotential at 400 mA/cm on 50 μm wide GSM surfaces. These patterned surfaces demonstrated superior HER performance compared to a plain gold surface, even with a 50% reduction in the reaction area. The optimal HER performance, characterized by the lowest total overpotential, was achieved on GSM surfaces with 200 μm wide gold strips, highlighting the intricate interplay between improved bubble dynamics and reduced reaction area.