Nickel-molybdenum hydrogen evolution and oxidation reaction electrocatalyst obtained by electrospinning

To accelerate the deployment of anion exchange membrane (AEM) technologies, and break free from our reliance on expensive and rare platinum group metals (PGM), this study explores a novel family of non-PGM electrocatalysts capable of both hydrogen evolution and oxidation. By thermal reduction, nanoparticles of nickel-molybdenum, 9:1 atomic ratio, were grown on fibrous carbon supports obtained by electrospinning and doped with carbon nanotubes (CNT). Complimentary characterization techniques confirm the integration of the CNT with the carbon fibers and a high loading of active alloy material on the support. In particular, XANES indicates a strong interaction between NiMo and the CNT. When supported on undoped carbon fibers, NiMo shows superior activity towards the hydrogen oxidation reaction (HOR) compared to the doped carbon supports. However, heat treating the catalysts in 10 % NH3/ 90 % N2 upsets this trend, while also improving the HOR performance of all the catalysts based on several performance indicators. In the case of NiMo on carbon fibers containing 7 wt% CNT, denoted as NiMo/CF(7 %), the ammonia heat treatment produced a five-fold increase in the kinetic current. The catalysts NiMo/CF(7 %)-NH3 and NiMo/CF(24 %)-NH3, also capable of hydrogen evolution, match other state-of-the-art PGM-free HOR catalysts for their remarkable specific activity.