Comparisons of formic acid oxidation at supported Pt catalyst and at low-index Pt single crystal electrodes in sulfuric acid solution

Abstract

The oxidation of formic acid was studied at supported Pt catalyst (47.5 wt%. Pt) and a low-index single crystal electrodes in sulfuric acid. The supported Pt catalyst was characterized by the TEM and HRTEM techniques. The mean Pt particle diameter, calculated from electrochemical measurements fits well with Pt particle size distribution determined by HRTEM. For the mean particle diameter the surface averaged distribution of low-index single crystal facets was established. Comparison of the activities obtained at Pt supported catalyst and low-index Pt single crystal electrodes revealed that Pt(111) plane is the most active in the potential region relevant for fuel cell applications.

Oksidacija mravlje kiseline ispitivana je na Pt katalizatoru nanetom na aktivni ugalj (47,5 mas % Pt) i na nisko-indeksnim Pt monokristalnim elektrodama u sumpornoj kiselini. Prvi katalizator je okarakterisan korišćenjem tehnika transmisione elektronske mikroskopije niske (TEM) i visoke rezolucije (HRTEM), pri čemu je određena distribucija, veličina i oblik nanočestica Pt. Srednji prečnik nanočestica, izračunat iz elektro hemijskih merenja, saglasan je raspodeli veličina čestica dobijenoj HRTEM analizom. Na osnovu srednjeg prečnika nanočestica data je prosečna distribucija (111), (100) i (110) mesta na površini katalizatora na nosaču. Ovaj katalizator je aktivniji u oksidaciji mravlje kiseline od monokristalnih Pt elektroda orijentacije (100) i (110), ali je manje aktivan od Pt(111) elektrode u oblasti potencijala relevantnoj za primenu u gorivnom spregu.