Nickel-Rhodium bimetallic dispersions supported on nickel foam as the efficient catalyst for urea electrooxidation in alkaline medium

The nickel-rhodium bimetallic dispersions supported on nickel foam (Ni-Rh/Ni foam) are prepared by the hydrogen-bubble templated electrodeposition of nickel on nickel foam (Ni/Ni foam) and the subsequent electrodeposition of rhodium on Ni/Ni foam. The physicochemical characterizations including FESEM, XRD, XPS and ICP show the Ni-Rh/Ni foam electrode owns highly porous structure and uniform unalloyed Ni-Rh dispersions, and loads minute amount of Rh (0.467 mg cm(-2)). By modulating the Rh electrodeposition time to 50 min, the Ni-Rh/Ni foam electrode exhibits the highest catalytic current density for urea electrooxidation and the most delayed oxygen evolution reaction. From the quadrant position of the Nyquist plots, the Rh component in Ni-Rh/Ni foam is found to exert no apparent effect on the anti-poisoning of intermediate (adsorbed CO2). Instead, Rh facilitates the formation of Ni(OH)(2), which contributes to the boost in the catalytic activity of Ni-Rh/Ni foam over Ni/Ni foam. This work suggests the Ni-Rh/Ni foam electrode is a promising anode catalyst for the urea electrooxidation-assisted hydrogen production and the simultaneous urea-containing sewage disposal. (C) 2019 Elsevier Ltd. All rights reserved.