Efficient Alkaline Hydrogen Evolution Reaction Using Superaerophobic Ni Nanoarrays with Accelerated H2 Bubble Release

• Published in: Advanced materials (Weinheim) 2023-12, Vol.35 (52), p.e2305844-n/a
• Main Authors: Kim, Jaerim, Jung, Sang‐Mun, Lee, Noho, Kim, Kyu‐Su, Kim, Yong‐Tae, Kim, Jong Kyu
• Format: Article
• Language: English
• Subjects: 3D nanostructures; bubble release; Bubbles; Catalysts; Control surfaces; electrocatalysts; Electrolysis; hydrogen evolution reaction; Hydrogen evolution reactions; Materials science; Nanorods; nickel; oblique angle deposition; Optimization; Porosity; superaerophobicity
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202305844

Despite the adverse effects of H2 bubbles adhering to catalyst's surface on the performance of water electrolysis, the mechanisms by which H2 bubbles are effectively released during the alkaline hydrogen evolution reaction (HER) remain elusive. In this study, a systematic investigation on the effect of nanoscale surface morphologies on H2 bubble release behaviors and HER performance by employing earth‐abundant Ni catalysts consisting of an array of Ni nanorods (NRs) with controlled surface porosities is performed. Both aerophobicity and hydrophilicity of the catalyst's surface vary according to the surface porosity of catalysts. The Ni catalyst with the highest porosity of ≈52% exhibits superaerophobic nature as well as the best HER performance among the Ni catalysts. It is found that the Ni catalyst's superaerophobicity combined with the effective open pore channels enables the accelerated release of H2 bubbles from the surface, leading to a significant improvement in geometric activities, particularly at high current densities, as well as intrinsic activities including both specific and mass activities. It is also demonstrated that the superaerophobicity enabled by highly porous Ni NRs can be combined with Pt and Cr having optimal binding abilities to further optimize electrocatalytic performance. Through a systematic investigation on the impact of nanoscale surface morphologies on H2 bubble release behaviors and hydrogen evolution reaction (HER) performance, it is revealed that highly porous catalyst consisting of an array of Ni nanorods exhibits the superaerophobic nature, leading to accelerated release of H2 bubbles from the surface along with effective open pore channels, and hence, remarkably enhanced HER performance.