Evolution of composition and structure of PtRh/C in the acidic methanol electrooxidation process

Abstract

PtRh alloys are highly active in the anodic methanol oxidation reaction (MOR) but few studies have looked at their evolution in the composition and structure during the catalytic process. Herein, a uniformly dispersed carbon-supported PtRh (PtRh/C) catalyst with Rh-enriched surface was synthesized via a facial hydrothermal method. By recording the performance of different cyclic voltammetry (CV) cycles during electrocatalytic MOR process in acid, the evolution of PtRh/C in composition and structure was elucidated. During the first 80 CV cycles, the rapid dissolution of the surface Rh atoms and the exposure of active Pt sites lead to the dramatic enhancement of the current density. When further continue the CV cycling, Pt atoms on the surface have aggregated and recombined to form a tightly aligned Pt-enriched surface. But Rh tends to be stable and catalytic performance reaches a relatively stable status with slightly decreased activity. Compared with the performance of PtRu/C catalyst, it can be concluded that PtRh/C has better stability and higher activity based on the less soluble property of Rh than Ru. Keywords: PtRh alloys, Anode catalysts, Methanol electrooxidation, Structural evolution, Compositional evolution