Improved ethanol electro-oxidation at Ni@Pd/C and Ni@PdRh/C core-shell catalysts

This paper describes the synthesis and catalytic activity of carbon-supported Pd/C, PdNi/C, and PdNiRh/C catalysts with core-shell morphologies towards the oxidation of ethanol in alkaline media. The catalysts are synthesised by a chemical reduction method using sodium borohydride as the reducing agent. Electrochemical characterisations show that the addition of Ni and Rh enhances remarkably the electrocatalytic activity of the materials due to the bifunctional and electronic effects in PdNi/C and PdNiRh/C catalysts, and the synergetic effect of the bifunctional and core-shell morphology on the Ni@Pd/C and Ni@PdRh/C catalysts. Electrochemical impedance spectra reveal lower values of charge transfer resistance for Pd60Ni20Rh20/C and Ni-20@Pd60Rh20/C. Chronoamperometric tests also reveal the Ni-20@Pd60Rh20/C catalyst displays current densities 9.3 times higher than the Pd/C catalyst. The superior catalytic performance of the trimetallic core-shell Ni-20@Pd60Rh20/C catalyst can result from the synergy between the metals and the presence of core-shell morphology. (C) 2020 Elsevier Inc. All rights reserved.