Understanding the electrochemical differences of Pt doped and Pt supported over CeO2

Abstract

Pt supported over CeO2 (Pt on CeO2) and Pt doped CeO2 (Pt in CeO2) are synthesized using chemical reduction and solution combustion method. In chemical reduction two different reducing agents are used namely; hydrazine hydrate and formaldehyde giving Pt supported over CeO2. Solution combustion method is used to prepare Pt doped CeO2. Detailed characterization using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area measurement and transmission electron microscopy (TEM) is carried out to distinguish the Pt supported and doped compounds. XRD and TEM results have clearly shown the differences in the structure and morphology, however, BET results do not show significant differences. Further, electrochemical measurements are performed in neutral medium to differentiate the electrochemical activity. Cyclic voltammetry (CV) indeed shows noticeable differences between Pt supported over CeO2 and Pt doped CeO2. CeO2 alone has also shown different electrochemical behavior compared to the Pt containing CeO2. Considering oxygen evolution reaction (OER) as a model reaction, Tafel slope measurements are performed for CeO2, Pt supported over CeO2 and Pt doped CeO2 to observe the differences. It was noted that CeO2 and Pt doped CeO2 showed similar Tafel slope indicating the same mechanism, while Pt supported over CeO2 showed different Tafel slopes, hence the different mechanism.