From powder morphology to catalytic behavior: Unraveling the role of spherical/flaky Al powders in cold-sprayed coating’s electrochemical activity for alkaline electrolysis

Hydrogen energy is regarded as a promising clean alternative to fossil fuels, yet the efficiency of hydrogen evolution reaction (HER) in alkaline electrolytes remains limited by the low catalytic activity of nickel-based electrodes. In this study, porous Ni electrodes were fabricated via cold spraying mixed powders of Ni + spherical Al or Ni + flake Al onto Ni substrates, followed by activation treatment. The influence of powder morphology on the porous structure and catalytic performance was systematically investigated. The Ni + spherical Al electrode exhibited remarkable HER activity, requiring only 0.32 V and 0.42 V overpotentials to achieve current densities of -100 and -250 mA cm⁻², respectively, while maintaining excellent durability under long-term cycling. These remarkable HER performance can be attributed to the synergistic effects of large electrochemical active surface area, excellent HER stability, and superior charge transfer capability.