Revealing the correlation between the hydrogen evolution reaction kinetics and multi-scale porous nickel electrode structure

A comprehensive understanding of electrode structure and electrode process kinetics is crucial for the design of advanced electrodes. To date, scholars have devoted considerable effort to elucidating the relationship between electrode structure and reaction kinetics. However, the understanding of the interactions among these factors remains quite limited once bubble dynamics are coupled. In this work, by adjusting the concentration of NH₄Cl during the electrodeposition process, we synthesize a series of electrodes with varying pore structures (size and density) and chemical compositions (hydrophilic vs. non-hydrophilic), and systematically characterize their electrochemical behaviors and bubble dynamics. The findings reveal that at low current densities (∼10 mA cm⁻²), electrodes with high specific surface areas and intrinsic activities exhibit optimal Hydrogen Evolution Reaction (HER) activity due to superior thermodynamic properties. In contrast, at higher current densities (∼1000 mA cm⁻², closer to industrial conditions), electrodes featuring larger pore sizes and higher hydrophilic material content demonstrate enhanced performance due to faster bubble detachment process. This work deeply understands the contributions of reaction and bubble dynamics to electrode process kinetics from a cross-scale perspective of electrode structure and emphasizes electrode structure design considers operational conditions.