Vertically grown Cr-doped NiFe2O4 nanosheets for bifunctional water splitting for high current density hydrogen production

To improve water electrolysis performance at high current densities, innovative materials must be developed into effective nanostructured electrocatalysts. This study presents the fabrication of self-supported pristine NiFe2O4 (NFO) and Cr-doped NiFe2O4 (CNFO) nanosheets on 3D-scaffold of nickel foam (NF) as bifunctional catalyst in alkaline water splitting. The overpotential for the NFO is 445 mV hydrogen evolution reaction (HER) and 1.640V Oxygen evolution reaction (OER), whereas CNFO displayed lowered overpotential of 384 mV (HER) and 1.533V (OER) to generate current density of 500 mA cm−2. The two electrode electrolyzer using CNFO required cell potentials of only 1.62V, 1.82V, and 2.22V to achieve current densities of 10, 100, and 500 mA cm−2, respectively, in industrial scale electrolyte 5M KOH. Additionally, it delivered a maximum current density of 800 mA cm−2 at a cell potential of 2.46V. The stability of the CNFO electrode demonstrated nearly constant performance over 40 h in an alkaline environment. The electrochemical performance of electrolyzer was also evaluated across a temperature range of 40 °C–80 °C. Present CNFO electrodes with nanostructured catalysts advocates significant development of robust electrodes for its technical applications for hydrogen production at higher current densities.