Direct Observation of Ni–Mo Catalyst Formation via Thermal Reduction of Nickel Molybdate Nanorods

Ni-Mo composites are known to catalyze several industrial relevant reactions involving hydrogen. Our interest is in Ni-Mo composites for hydrogen evolution reaction in alkaline anion exchange membrane water electrolyzers. We recently found that Ni-Mo composites comprise of core-shell structure where the core is metallic, rich in Ni while the shell is Mo-rich oxide. The transformation of the oxide intermediate into a core-shell architecture is studied in this work using in situ transmission electron microscopy. We reduced nickel molybdate nanorods in environmental transmission electron microscope and observed its transformation into the Ni-Mo catalyst composite. We further correlated these chemical transformations with the observed hydrogen evolution activity.