A Superaerophobic 3D Array Electrode Promotes Gas Bubble Management in Alkaline Water Splitting

Efficient gas bubble management is critical for enhancing the efficiency of alkaline water electrolysis, where adherent bubbles cause large overpotentials and unstable current densities. While optimizing the electrode structure has proven effective in promoting bubble detachment and improving reaction kinetics, achieving an ordered structure with a clear structure-performance relationship still remains challenging. Herein, a superaerophobic ordered 3D honeycomb Ni micromesh (3D HNM) integrated with NiCoP catalysts (3D HNM@NCP) is developed to address this challenge. By photolithography and the electrodeposition process, the hierarchical electrode is composed of a conductive Ni micromesh and Ni nanopyramids, which produces a discontinuous triple-phase contact line to minimize bubble adhesion. Operando high-speed imaging and finite element simulations reveal that the superaerophobic surface reduces bubble detachment size to ∼100 μm (compared with 150 μm for flat electrodes) and thus accelerates bubble release. As a result, the 3D HNM@NCP electrode exhibits an overpotential of 134 mV and demonstrates outstanding durability for over 60 h at 100 mA cm^-2 for the hydrogen evolution reaction. The overall water electrolysis enables over 24 h of chronopotentiometric steps at current densities up to 400 mA cm^-2. This work demonstrates an effective method to promote gas bubble removal with a 3D ordered structure with superaerophobic property for alkaline water electrolysis.