Stability of Ceria Supports in Pt-CeOx/C Catalysts

Pt-CeOx/C (1.5 <= x <= 2) catalysts are promising electrode materials in polymer electrolyte membrane fuel cells (PEMFCs), especially in direct methanol fuel cells. In this study, the chemical and microstructural features of the catalysts before and after electrocatalytic reactions were compared, and then the stability of ceria supports in the catalysts was studied. It was found that, during the impregnation of Pt on ceria, Pt particles will invade into the ceria supports and the ceria will be partly reduced. Subsequently, in an acidic condition that is required in a fuel cell using an Before reactions acid-based polymer electrolyte, the cent supports were instable and easily dissolved into the sulfuric acid solution. As a result, only a small amount of ceria remains around/between the Pt particles. The experimental result suggested that the dissolution of ceria could be due to the partial reduction of the ceria supports in the as-prepared catalysts. Although only a small amount of ceria could remain in the catalysts, it can effectively prevent the growth and sintering of Pt particles and contribute to the CO tolerance and higher catalytic activities of the Pt-CeOx/C catalysts.