Tuning electrode wettability to optimize nanobubble nucleation and reaction rates in water electrolysis

ZL Wang and YX Yu and MK Qin and H Jiang and ZJ Guo and L Bai and LM Wang and XC Zhang and XP Zhang and YW Liu, CHEMICAL ENGINEERING JOURNAL, 523, 168725 (2025).

DOI: 10.1016/j.cej.2025.168725

Bubble formation during water electrolysis can significantly hinder reaction efficiency by decreasing active area and obstructing mass transfer. In this work, using molecular simulations, the nanobubble nucleation on macro/ nanoelectrodes and its impact on reaction rates were investigated. As the electrode surface changes from hydrophobic to hydrophilic, regimes of gas layers, surface nanobubbles, bulk nanobubbles, and no nanobubbles are observed sequentially, along with a volcano-shaped relationship between wettability and current density (i.e., actual reaction rate). The optimal wettability balances the reactant concentration in the reaction zone and the surface bubble formation suppression. Applying appropriately elevated electrode potentials can further enhance reaction rates when no surface bubble forms, while excessive potentials cause surface nanobubble nucleation and reduced reaction rate. Nanoelectrodes exhibit higher reaction rates than macroelectrodes with the same wettability, owing to the increased reaction probability at electrode edges. These findings highlight the importance of optimizing electrode wettability, along with using suitable electrode potentials and nanostructured electrodes, to improve water electrolysis.

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