Polydopamine-functionalized multi-walled carbon nanotubes-supported palladium–lead bimetallic alloy nanoparticles as highly efficient and robust catalysts for ethanol oxidation

Abstract

High performance electrocatalysts of palladium–lead bimetallic alloy nanoparticles anchored onto polydopamine-functionalized multi-walled carbon nanotubes (PDA-MWCNTs) were fabricated by a facile one-step strategy. The PDA-MWCNTs, a superior electrocatalyst support, could be easily obtained through a mild and friendly method. Then, the palladium–lead alloy nanoparticles with different amounts of lead were uniformly anchored on the PDA-MWCNTs through a facile and surfactant-free one-step co-reduction approach. The morphologies, structures, compositional and electronic properties of the catalysts were analyzed by various techniques. As direct ethanol alkaline fuel cells (DEAFCs) catalysts, the new electrocatalysts exhibited improved electrocatalytic activities and enhanced electrochemical stabilities due to the synergistic effect of PDA and Pb as explained by the dispersive effect, bi-functional mechanism and d-band theory. In particular, the Pd₃Pb/PDA-MWCNTs, as the proposed catalyst, possesses a larger electrochemical active surface area, higher electrocatalytic activity, more negative onset oxidative potential and stability for ethanol electrooxidation compared to other as-prepared electrocatalysts. Therefore, the proposed electrocatalyst is a promising catalyst for DEAFCs and the PDA-MWCNTs is believed to have potential use in other fields as well.