Elaboration and Electrochemical Study of Ni and Mn-Based Deposit: Application as an Electrode for Fuel Cells

Abstract

The development of electrocatalysts with enhanced reactivity, stability, and costeffectiveness is a critical challenge in advancing sustainable energy systems. Large-scale applications such as hydrogen production and fuel cells often rely on expensive precious metals to ensure performance and durability. Designing efficient and affordable electrodes for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is essential for improving the viability of hydrogen energy technologies. The development of highperformance electrocatalysts for overall water splitting and fuel cell processes remains a significant hurdle in this field. This study investigated nonprecious metal-based electrodes, including Ni, Ni-Mn, Ni-MnCo, and Ni-Mn-Co-Fe thin films, as electrocatalysts for the HER, OER, and overall water splitting. The electrodes were synthesized via electrochemical deposition and characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) to analyze their morphology, surface roughness, and phase structure. The electrocatalytic performance of these materials was evaluated through linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) under alkaline conditions. The Ni-Mn-Co-Fe electrode demonstrated outstanding catalytic activity, requiring overpotentials of 436 mV for the HER and 447 mV for the OER to achieve a current density of 100 mA/cm². This performance is attributed to its unique microstructure, enhanced electrochemically active surface area, and synergistic interaction with its components. The electrode also exhibited excellent stability, with a less than 4% increase in overpotential after 20 hours of continuous electrolysis at 100 mA/cm². As a bifunctional electrode in watersplitting systems, it achieves a current density of 10 mA/cm² at a cell voltage of 1.57 V vs. RHE, highlighting its potential for practical applications. Key deposition parameters, including the bath composition, scan rate, pH, current density, applied potential, deposition time, supporting electrolyte, and temperature, were systematically optimized for the Ni, Ni-Mn, and Ni-Mn-Co-Fe films. The electrocatalytic performance was assessed in alkaline KOH solutions at various temperatures and concentrations. Comparative analysis of the deposition conditions, including scan rates (5–50 mV/s), pH values (1.5–7.5), V bath temperatures (25°C–60°C), and applied potentials (-0.5 to -1.4 V vs. Ag/AgCl), enabled a comprehensive understanding of the factors affecting catalytic efficiency. This study presents an effective strategy for producing active, stable, and cost-efficient electrocatalysts, demonstrating a scalable approach for renewable energy applications. These findings contribute to the development of high-performance catalysts for sustainable hydrogen production and fuel cell technologies