Ultralow Loading and High-Performing Pt Catalyst for a Polymer Electrolyte Membrane Fuel Cell Anode Achieved by Atomic Layer Deposition

Abstract

Decreasing Pt loading in the anode layer below ∼0.025 mg·cm –2 is found to reduce the hydrogen oxidation reaction rate during polymer electrolyte membrane fuel cells (PEMFCs) normal operation, when using conventional Pt/C catalysts and electrode coating methods. To achieve extremely low Pt loading in the anode catalyst layer while maintaining high PEMFC performance and durability, a series of membrane electrode assemblies (MEAs) with low Pt loading in the anode layer are successfully prepared using an atomic layer deposition (ALD) technique. When the ALD cycle number is controlled, the Pt nanoparticles (NPs) with different sizes and loadings are directly deposited on the carbon layer to form the anode catalyst layer. The ALDPt NPs with uniform particle sizes are highly distributed on the carbon surface, which promotes the ALDPt with high electrochemical active surface area and enables enhanced performance of ALDPt-MEAs. Particularly, the 50ALDPt-MEA with the anode Pt prepared by 50ALD cycles shows excellent H 2 –air PEMFC activity and durability. Importantly, the 20ALDPt-MEA with an ultralow anode Pt loading of 0.01 mg·cm –2 displays a significantly high surface area of 155 m 2 ·g –1 Pt, approximately 3 times higher than the 50.3 m 2 ·g –1 Pt for commercial Pt catalyst. The 20ALDPt anode also shows better stability than that of the commercial Pt/C during the anode potential cycling test. The ultralow Pt loading, uniform Pt distribution, high MEA performance, and durability achieved indicate that the ALD technique has great potential in developing high-performing electrocatalysts for PEMFC.