Hierarchical-heterostructured porous intermetallics in nickel-cobalt-aluminum alloys as efficient electrocatalysts for hydrogen evolution

Extensive researches have unequivocally revealed the remarkable potential of hierarchical porous intermetallic materials within the realms of electrocatalysis and energy materials. Nevertheless, the efficient and cost-effective synthesis of such electrocatalysts remains a challenging task, and the atomic-level mechanisms underlying hydrogen evolutions at active catalytic sites are still insufficiently comprehended. Herein, we report a novel synthesis technique for the hierarchical-heterostructured non-noble Ni-Co-Al intermetallics using spark plasma sintering followed by a selective dealloying process. This approach maximizes the electrochemical active surface area, thereby facilitating highly efficient hydrogen evolution reactions with an impressively low overpotential of only 75 mV at a current density of 10 mA cm⁻² and a Tafel slope of 54 mV dec⁻¹. Through operando X-ray absorption fine structure and theoretical calculations, the dynamic evolution process during the hydrogen evolution reaction procedure is investigated and the atomic Ni and Co sites are identified as synergistic catalytic sites. These characteristics render this hierarchical-heterostructured porous intermetallics appealing contenders for electrocatalysts utilized in high-performance large-scale hydrogen generation applications.