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

Nanostructuring of alloyed electrocatalysts with earth-abundanttransition metals represents a promising strategy for the practicalimplementation of water splitting to produce hydrogen. Here, we constructeda nanoporous CoNi alloy electrocatalyst with a unique three-dimensionalnanoweb structure on a nickel foam substrate. The optimized CoNi/NFelectrocatalyst exhibits excellent hydrogen evolution activity withan overpotential of 52 mV and a Tafel slope of 68 mV dec(-1). Furthermore, the high current density was sustained for 20 h withnegligible decrease. Such superior activity and stability outperformother reported electrocatalysts, originating from the synergisticeffect of Co and Ni metals and their unique porous 3D nanoweb structure,the latter are expected to create a large number of active sites forreaction. Density functional theory (DFT) calculations identifiedan increased density state at the Fermi energy level, which confirmsthe high electron density existing in the alloy structure.