MoO3-xNiMoO4 nanorods synthesized using NiO nanoparticles for hydrogen evolution in anion exchange membrane water electrolysis

The development of sustainable catalysts for anion exchange membrane water electrolysers (AEMWE) has attracted considerable attention in recent years due to the possibility of using earth abundant elements to replace platinum group metals (e.g. Pt, Ru, Ir) as catalysts. One class of promising materials for the hydrogen evolution reaction are nickel-molybdenum compounds. Here we present a novel method for preparing Mo-Ni based catalysts with high dispersion using commercially available NiO nanoparticles as seeds. A complete physical and morphological characterization indicates that the NiO particles act as nucleation centers for the growth of NiMoO4 nanorods. During high temperature reductive annealing, a MoO3-x rich layer forms on the surface of the rods. Electrochemical measurements demonstrate enhanced performance when compared to the analogous material produced using Ni foam. The powder catalyst was applied to a membrane electrode assembly using a catalyst coated substrate technique and tests in AEMWEs were carried out with electrodes of 78.5 cm2 area. A current density of 1 A cm−2 at a cell voltage of 1.8 V was obtained when coupled with an IrO2 anode. When combined with a non PGM NiCo2O4 anode, 1 A cm−2 of electrolysis current density was produced at 2.0 V.