Tailored nanocomposite FeNiB/MnO2/rGO@NF electrocatalyst for highly efficient and stable oxygen evolution reaction in freshwater and seawater environments

Efficient and stable electrocatalysts are of paramount importance for addressing the slow kinetics of the Oxygen Evolution Reaction (OER). In this study, we employ a robust strategy focusing on precise electronic modulation through nanocomposite structural engineering. FeNiB/MnO2/rGO@NF nanocomposites have been synthesized using a continuous hydrothermal method, with fine-tuned adjustments in the Ni/Fe ratio and boride content. The optimized composite, characterized by a Ni: Fe ratio of 2:1 and subjected to five boronization cycles, exhibited exceptional electrocatalytic performance in both alkaline freshwater (1.0 M KOH) and simular alkaline seawater (1.0 M KOH + 0.5 M NaCl). These materials achieved impressively low overpotentials of 266 mV and 276 mV to drive OER at 100 mA cm−2 in freshwater and seawater. Remarkably low Tafel slopes of 52.97 mV·dec−1 and 73.11 mV·dec−1 in alkaline freshwater and seawater, respectively, highlight their outstanding performance. The distinctive FeNiB/MnO2/rGO@NF composite amorphous structure emerges as a potent approach to fine-tune the catalyst's electronic configuration, significantly boosting OER performance. The incorporation of MnO2 within the rGO framework further mitigates agglomeration while creating additional catalytically active sites. This not only amplifies charge transfer capacity but also enhances overall electrochemical performance. The presence of nickel-iron boride renders the catalyst suitable for challenging seawater conditions, such as high salinity and corrosiveness. This study introduces a streamlined yet highly effective approach, offering a feasible and scalable route for crafting robust non-precious metal electrocatalysts tailored for OER applications in both freshwater and seawater environments.