NiWO3−x-Supported Pd Nanocluster Catalyst Boosts Hydrogen Oxidation Activity in Anion Exchange Membrane Fuel Cells

Slow reaction kinetics of the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) under alkaline conditions limits the performance of anion exchange membrane fuel cells and water electrolysers (AEMFC and AEMWE). Consequently, high loadings of PGM metal-based compounds such as Pd-CeO2 and PtRu are required to obtain competitive performance. The amount of precious metals present can be reduced by exploiting interaction with an active support material that tunes both hydrogen desorption and hydroxyl adsorption, processes that are key descriptors of HOR activity. In this work, NiWO3−xC is prepared, composed of oxygen-deficient tungsten oxide (WO3−x) doped with Ni nanoparticles and mixed with conductive carbon (50:50 wt%). This material is decorated with Pd nanoparticles (6.6 wt% Pd loading). Structural analysis (XRD, XPS, and HR-TEM/STEM) confirm a hybrid morphology of Pd nanoparticles deposited on both the Ni and W portions of the support. The HOR and HER activity was studied using electrochemical tests and compared to the performance of both a Pd/C standard with equivalent Pd loading (6.9 wt%) and the NiWO3−xC support. The Pd-normalized exchange current densities for the HOR (I0) are 18.7 A gPd−1 for Pd/NiWO3−xC and 3.21 A g−1 for Pd/C. The enhanced HOR activity of Pd/NiWO3−xC translates to high power densities in AEM fuel cell tests with this catalyst applied to the anode electrode (up to 0.9 W cm−2).