Effect of SnO2 Deposition Sequence in SnO2-Modified PtRu/C Catalyst Preparation on Catalytic Activity for Methanol Electro-Oxidation

Abstract

-modified PtRu/C catalysts were prepared in a polyol process to investigate the effect of a deposition sequence on the catalytic activity for methanol electro-oxidation. The structure, morphology, and chemical state of the prepared catalysts were characterized by X-ray diffraction, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy. The electrochemical activities were evaluated by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry measurements in combination with in situ IR reflection–absorption spectroscopy (IRRAS). Compared with those in the PtRu/C catalyst, a simultaneous deposition of PtRu and particles or a deposition of prior to PtRu improved the metal dispersion and decreased the alloyed Ru fraction. The deposition sequence of did not alter the chemical-state distribution of Pt and Ru but resulted in a different surface atomic ratio of Pt, Ru, and . Electrochemical and in situ IRRAS measurements indicated that the -modified PtRu/C catalyst prepared by the deposition of PtRu prior to gave the best catalytic activity for and methanol electro-oxidation among the PtRu/C and -modified PtRu/C catalysts. The roles of deposited with different sequences in the -modified PtRu/C catalysts were proposed.