Preparation and characterization of Pt–CeO2/C and Pt–TiO2/C electrocatalysts with improved electrocatalytic activity for methanol oxidation

Abstract

Pt–TiO2/C and Pt–CeO2/C electrocatalysts were synthesized by solid state reaction of TiO2/C and CeO2/C powders using intermittent microwave heating, followed by chemical reduction of platinum ions using mixed reducing agents of ethylene glycol and sodium borohydride. The crystal structure, surface morphology and chemical composition of prepared electrocatalysts were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The phase angle values of different Pt diffraction planes in Pt–TiO2/C and Pt–CeO2/C were shifted in the positive direction relative to those in Pt/C. Pt particles with diameter values of 3.06 and 2.78nm were formed in Pt–TiO2/C and Pt–CeO2/C, respectively. The electrochemical performance of prepared electrocatalysts was examined using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Pt–CeO2/C showed an enhanced oxidation current density when compared to Pt/C. Long time oxidation test at Pt–TiO2/C and Pt–CeO2/C revealed their improved stability. Lower charge transfer resistance values were estimated at Pt–metal oxide/C electrocatalysts.