Activation of dispersed PtSn/C nanoparticles by tungsten oxide matrix towards more efficient oxidation of ethanol

摘要

A novel electrocatalytic system for oxidation of ethanol, in which carbon-supported PtSn nanoparticles were modified with ultra-thin films/deposits of tungsten oxide, was proposed, fabricated and characterized here using electrochemical as well as spectroscopic (X-ray diffraction) and microscopic (transmission electron) techniques. The enhancement effect was evident from comparative diagnostic electrochemical experiments utilizing WO-3-modified and bare (unmodified) PtSn nanoparticles in acid medium (0.5moldm~(-3) H_2SO_4) at room temperature in the presence of ethanol. It is noteworthy that, the chronoamperometric electrocatalytic currents measured at potentials as low as 0.3 V (vs. RHE) were significantly larger for WO_3-modified PtSn/C relative to bare PtSn/C. In another diagnostic "stripping" experiment, it was found that oxidation of CO-adsorbate occurred in the presence of WO_3 at potentials almost lOOmV lower in comparison to the unmodified system. The overall activation effect may have origin in interactions of tungsten oxide with tin (from PtSn alloy nanoparticles) leading to stabilization of the catalytic tin oxo species.WO_3 may also provide large population of reactive oxo groups at the Pt/Sn-based electrocatalytic interface.