Influence of atomic layer deposition on nickel hydroxide phase transitions in nickel foam

This study investigates how Al 2 O 3 and V 2 O 5 coatings deposited on nickel foam by atomic layer deposition (ALD) modifies its electrochemical phase evolution in alkaline media. Phase transitions and surface kinetics were characterized using cyclic voltammetry (CV), in situ X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and Tafel analysis. Bare NF exhibits a positive cathodic peak shift for α-Ni(OH) 2 formation over 100 CV cycles attributed to surface activation. NF coated with Al 2 O 3 (NF-A) showed a larger shift (+90 mV) indicating enhanced charge transfer kinetics and reduced energy barrier. In contrast, V 2 O 5 -coated NF (NF-V) showed no shift suggesting a suppressed surface kinetics. These shifts disappear at higher scan rates suggesting a kinetic effect rather than a diffusion-induced behavior. Tafel and EIS measurements show that NF-A has the lowest charge transfer resistance, while NF-V exhibits the largest resistance. In situ XRD provides direct evidence for α-Ni(OH) 2 formation during extended cycling under alkaline conditions. These results demonstrate that different ALD coatings can selectively modulate surface kinetics and phase accessibility of nickel foam which can contribute to the design of nickel-based electrodes for phase-specific electrochemical applications. • Atomic layer deposition (ALD) tunes nickel hydroxide phase transitions in Ni foam. • In situ XRD reveals γ-NiOOH → α-Ni(OH)₂ conversion under controlled surface kinetics. • Al₂O₃-ALD lowers interfacial energy barrier, shifting α-Ni(OH)₂ formation by +90 mV. • V₂O₅-ALD stabilizes surface structure, suppressing kinetic phase evolution. • ALD enables phase-specific control of nickel electrodes for alkaline electrochemistry.