Issue 25, 2019

Synthesis of Pt@TiO2 nanocomposite electrocatalysts for enhanced methanol oxidation by hydrophobic nanoreactor templating

Abstract

In this work Pt@TiO2 nanocomposite electrocatalysts for methanol oxidation were synthesized using a one-pot process by hydrophobic nanoreactor templating. TiO2 was used as a support material for the platinum nanoparticles, thereby providing strong metal–support interactions. The Pt@TiO2 electrocatalyst consists of a monolayer of spherical superstructures comprising finely dispersed platinum nanoparticles in a crystalline TiO2 matrix as revealed by high resolution (scanning) transmission electron microscopy (HR-TEM and HR-STEM) combined with energy dispersive X-ray spectroscopy (EDX), electron diffraction and X-ray photoelectron spectroscopy (XPS). The Pt@TiO2 electrocatalyst showed high methanol oxidation activity, exceeding the activity of a commercial Pt/C catalyst by a factor of 2.5, as well as a cathodically shifted methanol oxidation peak. The increased methanol oxidation activity of Pt@TiO2 was attributed to its enhanced CO oxidation ability, an undesired intermediate, which is formed during methanol oxidation and poisons the Pt-surface. Indeed, CO stripping experiments confirmed that CO oxidation takes place at lower potentials in the case of Pt@TiO2, leading to a cathodic shift of the CO oxidation peak by 100 mV compared to a commercial Pt/C reference catalyst. Insights into the mechanism of methanol oxidation on Pt@TiO2 were found by comparison of methanol oxidation in different electrolytes. It was found that methanol oxidation via the CO-route is more pronounced on Pt@TiO2 than on Pt/C. The improved activity for CO oxidation resulted thereby in a better catalyst performance, especially at low potentials, and an increased stability, as demonstrated by chronoamperometry. The long-term stability of the catalyst was further addressed by accelerated stress tests (AST), which showed that the superior catalytic activity is retained even after 30 000 potential cycles.

Graphical abstract: Synthesis of Pt@TiO2 nanocomposite electrocatalysts for enhanced methanol oxidation by hydrophobic nanoreactor templating

Supplementary files

Article information

Article type
Paper
Submitted
25 jan 2019
Accepted
28 mai 2019
First published
14 jun 2019

Phys. Chem. Chem. Phys., 2019,21, 13555-13568

Synthesis of Pt@TiO2 nanocomposite electrocatalysts for enhanced methanol oxidation by hydrophobic nanoreactor templating

T. Unmüssig, J. Melke and A. Fischer, Phys. Chem. Chem. Phys., 2019, 21, 13555 DOI: 10.1039/C9CP00502A

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