Author: Guangrong DENG (The Hong Kong Polytechnic University) - Renewable electricity-driven water electrolysis provides a sustainable approach for green hydrogen production [1]. Anion exchange membrane water electrolysis (AEMWE) has gained considerable attention due to its ability to utilize non-precious metal catalysts and significantly reduce capital costs [2]. To make this technology closer to commercial applications, however, it is essential to achieve a high-rate hydrogen production . The key issue of water electrolysis is that bubble accumulation in porous electrode impedes water supply, particularly at high rates. To overcome this challenge, extensive research has focused on designing micro/nanostructured electrode surfaces with controlled morphology and surface wettability to improve bubble removal efficiency [3].
In this study, we develop a hierarchically structured stainless-steel electrode with grooved microchannels and a nanostructured surface to improve bubble removal efficiency and electrolysis performance. The grooved microchannels, fabricated through direct sintering, create preferred pathways for rapid bubble transport by inducing a self-pumping effect of bubbles that drive bubbles moving toward the flow channels. Concurrently, the nanostructured superhydrophilic surface, formed via controlled etching, reduces bubble adhesion by reducing the contact angle, thus promoting efficient bubble detachment. Through multi-scale bubble visualization, it can be observed that compared to commercial IrO₂-coated sintered titanium, the as-developed electrode significantly reduces the average bubble detachment diameter from 60 μm to 30 μm, accompanied by a two-fold enhancement in bubble release frequency, thereby demonstrating improved bubble removal efficiency. Furthermore, the as-developed electrode exhibits markedly improved electrolysis performance, with an overpotential reduction of approximately 120 mV at 5.0 A cm⁻² compared to the IrO₂-coated sintered titanium electrode.