On the effect of Cu on the activity of carbon supported Ni nanoparticles for hydrogen electrode reactions in alkaline medium

Effects of adding varied amounts of copper to carbon-supported nickel particles on their structure, composition and electrocatalytic activity for the hydrogen oxidation and evolution reactions in alkaline medium have been explored. Ni_1-xCu_x/C catalysts were prepared by the incipient wetness impregnation. Comprehensive characterization of the catalysts included X-ray powder diffraction, X-ray photoelectron spectroscopic, transmission electron microscopic and cyclic voltammetric analyses, while atomistic Monte Carlo simulations have been undertaken to obtain further insights into the structure of the bimetallic NiCu nanoparticles. We found that compared to monometallic Ni, NiCu nanoparticles show lower propensity towards oxidation under ambient conditions. Furthermore, we report that adding Cu allows increasing the surface-weighted electrocatalytic activity, and the specific surface area of Ni_1-xCu_x/C electrodes, both contributing to a ca four-fold enhancement of the massweighted activity. The nature of the synergistic interactions between Ni and Cu is proposed on the basis of the analysis of experimental data and Monte Carlo structural modelling results.