An Effective Approach towards the Immobilization of PtSn Nanoparticles on Noncovalent Modified Multi-Walled Carbon Nanotubes for Ethanol Electrooxidation

In this article, we describe an effective method to tether Pt and PtSn nanoparticles (NPs) on polyelectrolyte modified multi-walled carbon nanotubes (MWCNTs) for ethanol electrooxidation. By using a polymer wrapping technique, positively charged polyethyleneimine (PEI) was attached onto carbon nanotubes (CNTs) to provide preferential linking sites for metal precursors. Well-dispersed Pt and PtSn nanocrystals (2-5 nm) were subsequently decorated on PEI-functionalized MWCNTs through the polyol reduction method. The successful non-covalent modification of MWCNTs was confirmed by Fourier transform infrared spectroscopy (FTIR) and Zeta potential measurements. Energy dispersive X-ray (EDX) spectrum indicates approximately 20 wt % Pt loading and a desirable Pt:Sn atomic ratio of 1:1. Electrochemical analysis demonstrated that the as-synthesized PtSn/PEI-MWCNTs nanocomposite exhibited improved catalytic activity and higher poison tolerance for ethanol oxidation as compared to Pt/PEI-MWCNTs and commercial Pt/XC-72 catalysts. The enhanced electrochemical performance may be attributed to the uniform dispersion of NPs as well as the mitigating of CO self-poisoning effect by the alloying of Sn element. This modification and synthetic strategy will be studied further to develop a diversity of carbon supported Pt-based hybrid nanomaterials for electrocatalysis.