In situ preparation and high electrocatalytic activity of binary Pd-Ni nanocatalysts with low Pd-loadings

Palladium nanoparticles supported on multi-walled carbon nanotube (MWCNT), with ultra-low Pd loadings (wt%) of 1.1%-1.9%, have been prepared through an in situ reduction of Pd2+ by Ni nanoparticles immobilized on MWCNT. That is, Ni nanoparticles are firstly loaded on MWCNT by chemical reduction method to fabricate the catalyst nanoNi/MWCNT. Then, aqueous PdCl2 solution with various concentrations is added to the nanoNi/MWCNT catalyst stepwise, leading to the formation of Pd nanoparticles and subsequent in situ deposition on the nanoNi/MWCNT. The as-synthesized nanocatalysts (Pd4.1Ni1/MWCNT, Pd3.7Ni1/MWCNT and Pd1.3Ni1/MWCNT) have been characterized by SEM, XRD and XPS. Their electrocatalytic activity for ethanol oxidation in alkaline media has been investigated. Compared to the Pd/MWCNT catalyst prepared by the conventional NaBH4 reduction method, the asprepared Pd-Ni/MWCNT catalysts present low Pd-loading and significantly high electroactivity for ethanol oxidation. According to the cyclic voltammetric data, the forward-scan anodic peak current density j(Pd) on the Pd3.7Ni1/MWCNT catalyst is 130.9 mA cm(-2) mu g(-1), which is over 11 times higher than on the Pd/MWCNT. (C) 2015 Elsevier Ltd. All rights reserved.