Atomic layer deposition assisted Pt-SnO2 hybrid catalysts on nitrogen-doped CNTs with enhanced electrocatalytic activities for low temperature fuel cells

Nitrogen doped carbon nanotubes (CNx) of a high nitrogen concentration were synthesized directly on carbon paper as the skeleton of a 3D composite electrode. Ultra-fine SnO2 nanoparticles about 1.5 nm were deposited on CNx with atomic layer deposition (ALD) technique. Pt nanoparticles from 1.5 to 4 nm were deposited on CNx/carbon paper and SnO2/CNx/carbon paper with ethylene glycol reduction method. Three dimensional Pt/CNx/carbon paper and Pt-SnO2/CNx/carbon paper composite electrodes were obtained, respectively. They were characterized over oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) for low temperature fuel cells. With similar sizes of Pt nanoparticles, the electrochemical surface area (ECSA) of Pt-SnO2/CNx/carbon paper is larger than that of Pt/CNx/carbon paper. Pre-deposited SnO2 nanoparticles promote the electrocatalytic activity of Pt toward ORR, carbon monoxide (CO) stripping and MOR. The underlying mechanisms for the enhanced activities are discussed.