Enhancement of activity of platinum towards oxidation of ethanol by supporting on titanium dioxide containing phosphomolybdate-modified gold nanoparticles

摘要

A new concept of utilization or titanium dioxide matrix in electrocatalysis by admixing it with polyoxometallate modified gold nanoparticles is described here. The approach utilizes Keggin-type phosphododecamolybdate (PMo_12O_40~3-) adsorbates capable of modifying, activating and stabilizing Au nanoparticles of the sizes of 30-40 nm. Ultra-thin films of phosphomolybdates on nanostructured gold are characterized by well-defined fast (reversible) multi-electron electrochemical reactions. By dispersing platinum black over the Au-containing TiO_2, the electrocatalytic activity of Pt nanoparticles towards oxidation of ethanol has been enhanced. Remarkable increases of electrocatalytic currents measured under voltammetric and chronoamperometric conditions have been observed. The most likely explanation takes into account improvement of overall conductivity (due to the presence of nanostructured gold) at the electrocatalytic interface (including TiO_2-support), as well as and possibility of specific Pt-TiC>2 or Pt-Au electronic interactions and existence of active hydroxyl groups (on titanium dioxide or polyoxometallate surfaces) in the vicinity of catalytic Pt sites.