Mesoporous Hollow Cu-Ni Alloy Nanocage from Core-Shell Cu@Ni Nanocube for Efficient Hydrogen Evolution Reaction

We have created a facial self-templated method to synthesize three distinct nanostructures, including the unique edge-cut Cu@Ni nanocubes, edge notched Cu@Ni nanocubes, and mesoporous Cu-Ni nanocages by selective wet chemical etching method. Moreover, in the synthesis process, the corners of edge cut Cu@Ni nanocubes and mesoporous Cu-Ni nanocages can be etched to produce the highly catalytically active (111) facets. Impressively, compared to edge-notched Cu@Ni nanocubes and edge-cut Cu@Ni nanocubes, the Cu-Ni nanocages exhibit higher electrocatalytic activity in the hydrogen evolution reaction (HER) under alkaline conditions. When obtained overpotential is 140 mV, the current density can reach 10 mA cm(-2); meanwhile, the corresponding Tafel slope is 79 mV dec(-1). Moreover, from the calculation results of density functional theory (DFT), it can be found that the reason why the activity of pure Ni is lower than that of Cu-Ni alloy is that the adsorption energy of the intermediate state (adsorbed H*) is too strong. Meanwhile the Gibbs free-energy (vertical bar Delta G(H*)vertical bar) of (111) facets is smaller than that of (100) facets, which brings more active sites or adsorbs more hydrogen.