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Summary: Developing a non‐precious or low Pt‐group metal‐containing (low‐PGM) hydrogen oxidation reaction (HOR) catalyst is crucial to fabricate economic anion exchange membrane fuel cells (AEMFCs), an alternative to proton exchange membrane fuel cells (PEMFC). In this study, low‐PGM Ni100‐xRhx electrocatalysts, seldomly studied as alkaline HOR catalysts, with various compositions are fabricated via electrodeposition. Substantial changes are observed in both the morphology and crystalline structure of the catalysts when Ni is alloyed with Rh, such as enlarged surface area and development of different textures. The HOR activities of Ni100‐xRhx catalysts evaluated in 0.1 M KOH solution are dramatically enhanced because of the enlarged surface area, bifunctional roles of H‐providing sites (Ni/Rh) and OH‐providing sites (Ni[OH]2/Rh2O3), and their balanced composition on the surface. The durability of Ni89Rh11, the most appropriate catalyst, is investigated with the 3000 potential cycling, giving the average decay rate of approximately 0.30 μA cm−2/cycle. The origin of enhanced activity and degradation during durability test was explained in terms of the electronic structures and surface composition of the catalysts. The initial high HOR activity of about 1.5 mA/cm2 for Ni89Rh11 at 0.05 VRHE, though it requires a further improvement in the durability, suggests the practical feasibility of it as a low PGM alkaline HOR catalyst. [ABSTRACT FROM AUTHOR]

Summary: To realize nonprecious‐metal catalysts with practical applicability for the hydrogen evolution reaction (HER), improved corrosion resistance and catalytic activity are required. In this study, composition‐controlled Co‐Cu alloys were fabricated by electrodeposition for use as HER catalysts in proton exchange membrane water electrolyzers (PEMWEs). As the Cu content in the alloy increased, the morphology changed from needle‐shaped particles to small round particles. Furthermore, a phase transition from a hexagonal close‐packed structure to a face‐centered cubic structure occurs because the latter structure is stabilized by adding Cu to Co. The optimum catalyst composition for the HER was found to be Co59Cu41, which had an overpotential of 342 mV at −10 mA cm−2. This catalyst exhibited excellent durability, showing a potential reduction of approximately 100 mV over 12 hours under a constant current density. This superior performance was attributed to the increase in the electrochemical surface area resulting from the addition of Cu, as confirmed by electrochemical double layer capacitance measurements, in addition to a counterbalance between the hydrogen adsorption energies of Co and Cu. Finally, the application of the Co‐Cu alloy catalyst as a cathode catalyst in a PEMWE resulted in excellent performance of 1.2 A cm−2 at 2.0 Vcell. [ABSTRACT FROM AUTHOR]