Se-Doped Magnetic Co–Ni Spinel Ferrite Nanoparticles as Electrochemical Catalysts for Hydrogen Evolution

The magnetic Co0.5Ni0.5Fe2O4 spinel ferrites (NSFs) with various (x%) Se (x = 0.00–0.20) were synthesized via the sol–gel combustion route in conjunction with an advanced green laser ablation method. The structure and morphology of NSFs were explored through various physicochemical techniques. Interestingly, Se doping has a crucial impact on NSFs’ magnetic properties. While, at room temperature, the pristine sample exhibits a superparamagnetic-like behavior, the pristine sample and all doped CoNi NSFs + x% Se (x = 0.05–0.20) samples exhibited a high value of coercivity and remanence at 10 K, indicating their hard magnetic properties. Our findings indicate that Se can be harnessed to tune the magnetic properties of CoNiFe2O4 structures. In addition, improving effective electrocatalysts for hydrogen evolution reaction (HER) efficiency through water splitting is also vital to overcoming the impending energy crisis due to the rapid depletion of fossil fuels and their injurious impact on the environment. Hence, the optimized ideal catalysts CoNi NSFs + x% Se (x = 0.15) were developed, which outperformed as electrocatalysts for HER with a Tafel slope of 91 mV/dec and a very low overpotential of 173.5 mV at a current density of 10 mA/cm2, which could be attributed to a large number of electrochemically active surface area (5.2 cm2), accelerated electron mobility at the electrocatalysts/electrolyte interface, and long-term stability.