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

• Synthesis of MoO 3-x surface NiMoO 4 nanorods using commercial NiO nanopowder seeds. • Roughened surface rich in MnO3-x demonstrated by HR-TEM and Raman spectroscopy. • Evolution of hydrogen at high pH is enhanced compared to sample made with Ni foam. • 1 A cm 2 current density at 1.8 V with IrO2 anode and at 2 V with NiCo2O4 anode. 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 NiMoO 4 nanorods. During high temperature reductive annealing, a MoO 3-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 cm 2 area. A current density of 1 A cm −2 at a cell voltage of 1.8 V was obtained when coupled with an IrO 2 anode. When combined with a non PGM NiCo 2 O 4 anode, 1 A cm −2 of electrolysis current density was produced at 2.0 V.