Carbon supported PtRh catalysts for ethanol oxidation in alkaline direct ethanol fuel cell

摘要

Owing to the formation of an oxametallacyclic conformation, the C-C bond cleavage is the preferential channel for the ethanol dissociation on the Rh surface, the addition of Rh to Pt can increase the CO_2 yield during the ethanol oxidation. However, in acidic media the slow oxidation kinetics of CO_(ads) to CO_2 limits the overall reaction rate. In this work, we prepare carbon supported PtRh catalysts and compare their catalytic activities with that of Pt/C in alkaline media. Cyclic voltammetry tests demonstrate that the Pt_2Rh/C catalyst exhibits a higher activity for the ethanol oxidation than Pt/C does. Linear sweep voltammetry tests show that the peak current density on Pt_2Rh/C is about 2.4 times of that on Pt/C. The enhanced electro-activity can be ascribed not only to the improved C—C bond cleavage in the presence of Rh, but also to the accelerated oxidation kinetics of CO_(ads) to CO_2 in alkaline media.