Testing of Catalyst Coated Membranes for PEMFC, Prepared by Electrospray Deposition

Abstract

Catalyst layers deposited on the membrane are compared with similar layers deposited on the gas diffusion layer (GDL), using the electrospray deposition method. The objective double: first, to explore the viability of this method for 'on membrane' deposition of Pt/C+Nafion films, and, second, to know the differences in single cell performance that this procedure introduces with respect to the 'on GDL' deposition. It is found that electrospray deposition is able to produce 'on membrane' deposited catalyst layers with good adherence. In addition, on membrane deposited cathodic catalyst layers have superior performance in single cells, compared with the same films deposited on the GDL. The analysis of polarization curves shows that the improvement is due to a decrease in the internal resistance of the cell, whereas electrocatalytic activity and active area maintain unchanged. The lower internal resistance corresponds to a decrease in the high frequency contribution (1 kHz), so it appears to indicate that on membrane deposition improves the fast ionic conduction processes at the cathodic catalyst layer-membrane interface. The good performance of electrospray deposited catalyst layers shown in previous works, and the possibility for on-membrane deposition demonstrated here, opens a new way to prepare PEMFC electrodes with high efficiency and low catalyst loading.