Synthesis, characterization and electrochemical studies of nanostructured CaWO4 as platinum support for oxygen reduction reaction

In the present work, we employed nanostructured calcium tungstate as a supporting material for platinum, a well-known electrocatalyst for oxygen reduction. The co-precipitation method has been utilized to synthesize nanostructured calcium tungstate from aqueous solution. The structure and morphology of the obtained CaWO4 were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Preparation of the Pt/CaWO4-graphite catalyst was carried out by electrodeposition of Pt onto the surface of CaWO4/graphite electrode. The physical properties of the catalyst were determined by scanning electron microscopy analysis and energy dispersive X-ray (SEM/EDX). The electrochemical activity of the Pt/CaWO4-graphite for the oxygen reduction reaction (ORR) was investigated in acid solution by cyclic voltammetry measurements, linear sweep voltammetry, and electrochemical impedance spectroscopy. The results revealed that the Pt/CaWO4-graphite has higher electrocatalytic activity for oxygen reduction in comparison with Pt/graphite catalyst.