Electrode morphology and structural engineering accelerates bubble detachment dynamics in NiFe porous electrodes for alkaline water electrolysis

The optimization of electrode structure and bubble dynamics is critical for enhancing the efficiency of alkaline water electrolysis, particularly for the oxygen evolution reaction (OER). While previous studies have focused on improving electrode kinetics through structural modifications, the coupled effects of bubble evolution and electrode design under high-current-density conditions remain insufficiently explored. This study investigates how electrode porosity, surface roughness, and material composition influence bubble behavior and OER performance. By systematically tuning the concentrations of Ni²⁺ and Fe²⁺ during electrodeposition, a series of porous NiFe electrodes with tailored pore structures and surface properties are synthesized. Advanced characterization techniques, including contact angle measurements, in-situ bubble photography at high current density, and electrochemical testing, are employed to analyze the interplay between bubble dynamics and electrode kinetics. The findings reveal that the balance between electrode roughness and pore size critically influences bubble behavior: larger pores promote faster bubble detachment and reduce overpotential due to increased roughness, while smaller pores lead to bubble clogging and impaired performance. Additionally, the study demonstrates that at low current densities, thermodynamic properties-such as high surface area-predominantly determine electrode performance. However, at high current densities, bubble dynamics become the primary determinant of overall performance, highlighting the importance of optimizing electrode structures to mitigate bubble-related losses. This work provides critical insights into the fundamental factors governing bubble dynamics and their impact on electrode performance, offering valuable guidance for the design of industrial-scale alkaline water electrolysis systems.