Nickel-Tungsten Composite Anodes, in Anion Exchange Membrane Fuel Cells

Abstract

Fuel cell technology has been undergoing huge developments recently, and the most fundamental progress is the electrolyte being replaced with polymer electrolytes, specifically in the field of anion exchange ionomers, which has enabled an increase in power density for AEMFCs. Currently, acidic polymer electrolytes are widely used. Fuel cells based on acidic electrolytes are very successful but they heavily depend on noble metal catalysts and among those mostly on Pt. Therefore, there is a strong need for PGM-Free catalysts to reduce the cost and facilitate the widespread application of such fuel cells [1]. Due to improved kinetics for ORR in alkaline media, it is necessary to also develop PGM-Free anode catalysts for HOR. Between all PGM-Free metals, Ni has shown a significant potential in catalyzing HOR reaction, however, due to oxidation of Ni in alkaline media, as well as the need to tune the binding energy of adsorbed hydrogen (Had) on the nickel active sites, alloying Ni with other PGM-Free transition metals is a promising strategy to improve the HOR performance as well as the stability of these catalysts. It has also been shown that Tungsten doped nickel can act as a stable catalyst in alkaline media toward HOR. [2], [3] We prepared NiW composites (which activity is shown in figure 1.) using Incipient Wetness Method (IWM), adding compounds of Ni and W to carbon support and then pyrolyzed for the composite to form and stabilize on the carbon support. Here, we will present on advances in the NiW system for HOR in alkaline media relating to: electrochemical corrosion, MEA performance and the role of the support material on HOR kinetics and stability of these NiW composites.