Investigating the Impact of Electrolyte Temperature on the Oxygen Evolution Reaction Efficiency of Ni-Co/NiFelt Nano Composite Electrode

Alkaline water electrolysis (AWE) emerged as a viable alternative for producing eco-friendly hydrogen and has been a cornerstone in industrial hydrogen generation particularly through non-noble electrocatalysts [1]. Many studies focused on a three-electrode setup for studying the electrochemical behavior of electrocatalysts at room temperature (25°C) while some considered the electrolyte temperature at 60-80 °C in the AWE cell related to industrial applications [2]. The temperature of the electrolyte has a substantial impact on several aspects of the electrochemical reaction such as double-layer charging, electron charge transfer, diffusion in terms of mass transfer, and overall electrochemical processes at the electrodes. As a result, temperature changes affect the adsorption and dissociation of H2O or OH- species on electrocatalysts, as well as the production and desorption of H2 and O2 molecules from the surface of electrocatalysts. Considering these effects, electrolyte temperature is critical in evaluating the performance of electrocatalysts intended for industrial applications in AWE [3]. To this end, a nanocomposite of Ni-Co is synthesized with the hydrothermal method followed by calcination and used as a binder-free method to coat this electrocatalyst onto the NiFelt as gas diffusion layer (GDL) [4]. The investigation used a standard threeelectrode setup, employing Pt wire as the counter electrode, Hg/HgO as the reference electrode, and a selfmade Ni-Co/NiFelt nanocomposite electrode as the working electrode. Temperatures ranging from 20 to 80°C were tested to identify the optimal current density considering the stability. Various tests, including linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), chronopotentiometry, and chronoamperometry, were conducted to assess electrode activity. As expected, an increase in the KOH electrolyte temperature has shown an improvement in the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) kinetics. However, this rise in temperature compromised reaction stability due to increased conductivity, heightened hydrophilicity, more active sites, and reduced electrolysis resistance.