Active Co _<b>3</b> O _<b>4</b> Nanosheet Integration and Morphological Tuning of Ni Nanocones for Efficient Electrocatalytic Hydrogen Generation

The growing demand for sustainable energy highlights the importance of developing efficient electrocatalysts for the hydrogen evolution reaction (HER). Achieving superior HER performance requires not only high catalytic efficiency but also precisely engineered geometric and electronic features, as bubble nucleation, growth, and detachment strongly influence the overall efficiency. Despite their apparent differences, these processes share common challenges, such as bubble blockage, restricted reactant access, and delayed product removal. Herein, a competitive electroreduction strategy is adopted for fabricating a Ni/Co3O4 nanocone-nanosheet hybrid electrode for HER. Nickel nanocones (NNCs), with their sharp geometry, provide abundant active sites but are prone to bubble trapping, which limits electrolyte accessibility and long-term durability. To address this challenge, cobalt oxide (Co3O4) nanosheets are integrated onto the nanocone framework, introducing both morphological and electronic modifications. The nanosheet integration facilitated rapid bubble detachment and improved mass transport, while interfacial electron transfer from Ni to Co3O4 optimized the local electronic structure, accelerated charge transfer, and enhanced the intrinsic catalytic activity. As a result, the Ni/Co3O4 nanocone-nanosheet hybrid electrode delivered a higher current response, superior HER performance, and excellent long-term stability. This work demonstrates the synergistic effect of structural and electronic engineering in advancing efficient electrocatalysts for sustainable hydrogen production.