A Green Solvent-Free Approach Synthesis for Rational Designing of a NiFe-Layered Double Hydroxide [NiFe-LDH] Electrocatalyst for Hydrogen Generation

Creating cost-effective, chemically stable electrocatalysts to improve the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a major challenge in electrocatalytic water splitting. We synthesized a highly efficient NiFe-layered double hydroxide (LDH) electrocatalyst using a solvent-free method. The formation of well-interconnected metal ions with nanospherical architectures created an extensive electrochemically active surface area enriched with catalytically active sites, demonstrating synergistic effects. Preserving the suitable stoichiometric ratio, such as Ni6Fe4LDH, was crucial in enhancing the catalytic performance for both the HER and OER. The optimal Ni6Fe4LDH ratio established overpotentials of 167 mV (112 mV dec–1) for the HER and 280 mV (116 mV dec–1) for the OER, attaining a 10 mA cm–2current density in 1 M KOH. Moreover, Ni6Fe4LDH demonstrated impressive robustness, stable up to 90 h with a minor decrease of 4.1 and 4.6% in the current density for the HER and OER. Notably, in the bifunctional two-electrode arrangement of Ni6Fe4LDH/NF||Ni6Fe4LDH/NF, effective water electrolysis was accomplished, preserving a stable 10 mA cm–2current density at a bias of 1.64 V for over 140 h, with a slight current loss of 3.9% of the current density.