Crucial size effects of atomic-layer-deposited Pt catalysts on methanol electrooxidation

Abstract

Fundamental understanding of the size effects of Pt-electrocatalyzed methanol oxidation reaction (MOR) in the alkaline media is rarely explored, especially from the viewpoint of catalyst active sites. Herein, we report a remarkable size-dependent MOR activity of atomic-layer-deposited Pt nanoparticles on CNT. The surface properties of CNT are tailored, and using the growth temperature of 600 °C followed by the oxidation treatment is found to yield an attractive support, i.e., CNT-600-O, for the fabrication of highly active Pt catalysts. On such support, the 1.9 nm sized Pt catalyst gives rise to the highest peak current density, which is approximately 3.2 times higher than the commercial Pt/C catalyst. The underlying nature of the Pt size effects is further elucidated by the model calculations together with HRTEM and XPS measurements. The Pt corner sites are discriminated as the dominant active sites, and the lower Pt° 4f binding energy favors the reaction. The insights revealed here could shed light on the fabrication of highly efficient Pt-based MOR catalyst by tailoring the quantity and quality of the catalyst active sites.