Preparation of Pt-Co alloy catalysts by electrodeposition for oxygen reduction in PEMFC

Direct current (DC) and pulse current (PC) electrodeposition of Pt-Co alloy onto pretreated electrodes has been conducted to fabricate catalyst electrodes for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). The effect of plating mode and pulse plating parameters on the Pt-Co alloy catalyst structure, composition and electroactivity for the ORR in PEMFC has been investigated. The electrodeposited Pt-Co alloy catalyst indicates higher electrocatalytic activity towards the ORR than the electrodeposited Pt catalyst. The activity of the electrodeposited Pt-Co catalysts is further improved by applying the current in a pulse waveform pattern. The electrodeposition mode and the pulse plating parameters do not have the significant effect on the Pt: Co composition of deposited catalysts, but show the substantial effect on the deposit structures produced. The Pt-Co catalysts prepared by PC electrodeposition have finer structures and contain smaller Pt-Co catalyst particles compared to that produced by DC electrodeposition. By varying the Pt concentration in deposition solution, the Pt: Co composition of the electrodeposited catalyst that exhibits the highest activity is found. The Pt-Co alloy catalyst with the Pt: Co composition of 82: 18 obtained at the charge density of 2 C cm(-2), the pulse current density of 200 mA cm(-2), 5% duty cycle and 1 Hz was found to yield the best electrocatalytic activity towards the ORR in PEMFC.