A hybrid catalyst of Pt/CoNiO2 on carbon nanotubes and its synergetic effect towards remarkable ethanol electro-oxidation in alkaline media

Abstract

Herein, a hybrid catalyst of Pt/CoNiO₂ on carbon nanotubes (Pt/CoNiO₂–CNTs) has been successfully synthesized by a facile and cost-effective method, and its crystal structures, chemical valence states, and morphologies have been characterized in detail. CO stripping voltammograms reveal that the adsorbed CO_ads on the active sites of the Pt/CoNiO₂–CNT catalyst is easily oxidized at a lower potential (−0.60 V) as compared to the Pt particles on rGO (−0.35 V) and acid-treated CNTs (−0.36 V). Cyclic voltammograms demonstrate that the designed Pt/CoNiO₂–CNT catalyst possesses an ultrahigh electrocatalytic activity (1136.2 mA mg_Pt⁻¹) for ethanol oxidation, which is 5.1 and 3.0 times higher than that of Pt/rGO (221.6 mA mg_Pt⁻¹) and Pt/CNTs (375.4 mA mg_Pt⁻¹), respectively. The Tafel plot of Pt/CoNiO₂–CNTs is 205 mV dec⁻¹, indicating much faster reaction kinetics than that of the compared catalysts. In addition, the outstanding long-term stability indicates that the designed Pt/CoNiO₂–CNT catalyst exhibits expected application prospects in direct alkaline ethanol fuel cells. Moreover, the catalytic mechanism of the hybrid Pt/CoNiO₂–CNTs has been proposed and discussed via C2 and C1 pathways with respect to the final products for CH₃COO⁻ and CO₃²⁻, respectively.