Controllable Synthesis of the Three-Dimensional Co–Ni Nanoweb Structure for Electrocatalytic Hydrogen Evolution Reaction

Nanostructuring of alloyed electrocatalysts with earth-abundant transition metals represents a promising strategy for the practical implementation of water splitting to produce hydrogen. Here, we constructed a nanoporous CoNi alloy electrocatalyst with a unique three-dimensional nanoweb structure on a nickel foam substrate. The optimized CoNi/NF electrocatalyst exhibits excellent hydrogen evolution activity with an overpotential of 52 mV and a Tafel slope of 68 mV dec –1 . Furthermore, the high current density was sustained for 20 h with negligible decrease. Such superior activity and stability outperform other reported electrocatalysts, originating from the synergistic effect of Co and Ni metals and their unique porous 3D nanoweb structure, the latter are expected to create a large number of active sites for reaction. Density functional theory (DFT) calculations identified an increased density state at the Fermi energy level, which confirms the high electron density existing in the alloy structure.