Cyclic voltammetry electrodeposition of Fe–Mn–P nanoflake coatings on nickel foam: Process optimization, surface characteristics, and alkaline hydrogen evolution performance

Water electrolysis is a promising technology for sustainable hydrogen production, yet its large-scale implementation requires electrocatalysts that combine high activity, durability, and low cost. In this study, Fe–Mn–P nanoflake coatings were successfully deposited on nickel foam via a facile, scalable cyclic voltammetry electrodeposition process and evaluated as binder-free cathodes for the hydrogen evolution reaction (HER) in alkaline media. The influence of electrodeposition parameters, including cycle number (5–50 cycles) and scan rate (5–50 mV s⁻¹), on the coating morphology and electrochemical performance was systematically investigated. Structural characterization revealed the formation of a rough nanoflake coating with a predominantly amorphous structure, providing abundant electrochemically accessible active sites. The optimized Fe–Mn–P coating, obtained at 50 deposition cycles and a scan rate of 20 mV s⁻¹, exhibited excellent HER activity in 1 M KOH, requiring overpotentials of only 76 and 181 mV to achieve current densities of 10 and 100 mA cm⁻², respectively. Electrochemical analyzes demonstrated a low apparent charge-transfer resistance of 2.6 Ω cm², a Tafel slope of 69 mV dec⁻¹, and a high electrochemically active surface area of 210 cm², suggesting favorable electrochemical behavior and enhanced availability of catalytic sites. Comparative investigations revealed that the ternary Fe–Mn–P coating outperformed the corresponding Fe–P and Mn–P coatings, highlighting the beneficial synergistic interaction among Fe, Mn, and P species. Furthermore, the coating maintained stable HER performance at 100 mA cm⁻² for 20 h and exhibited enhanced resistance to alkaline corrosion during prolonged immersion tests. The superior electrochemical performance is attributed to the combined effects of the amorphous nanoflake morphology, increased active surface area, and strong coating adhesion to the nickel foam substrate. These findings demonstrate that cyclic voltammetry electrodeposition offers an effective strategy for fabricating durable Fe–Mn–P coatings and provides a promising route toward low-cost electrocatalysts for alkaline water electrolysis.