Mesoporous Hollow Cu–Ni Alloy Nanocage from\nCore–Shell Cu@Ni Nanocube for Efficient Hydrogen Evolution\nReaction

Abstract

We have created a\nfacial self-templated method to synthesize three\ndistinct nanostructures, including the unique edge-cut Cu@Ni nanocubes,\nedge-notched Cu@Ni nanocubes, and mesoporous Cu–Ni nanocages\nby selective wet chemical etching method. Moreover, in the synthesis\nprocess, the corners of edge-cut Cu@Ni nanocubes and mesoporous Cu–Ni\nnanocages can be etched to produce the highly catalytically active\n(111) facets. Impressively, compared to edge-notched Cu@Ni nanocubes\nand edge-cut Cu@Ni nanocubes, the Cu–Ni nanocages exhibit higher\nelectrocatalytic activity in the hydrogen evolution reaction (HER)\nunder alkaline conditions. When obtained overpotential is 140 mV,\nthe current density can reach 10 mA cm^–2; meanwhile,\nthe corresponding Tafel slope is 79 mV dec^–1. Moreover,\nfrom the calculation results of density functional theory (DFT), it\ncan be found that the reason why the activity of pure Ni is lower\nthan that of Cu–Ni alloy is that the adsorption energy of the\nintermediate state (adsorbed H*) is too strong. Meanwhile the Gibbs\nfree-energy (|Δ<i>G</i>_H*|) of (111) facets\nis smaller than that of (100) facets, which brings more active sites\nor adsorbs more hydrogen.