A facile synthesis of metal ferrites (MFe2O4, M = Co,Ni, Zn,Cu) as effective electrocatalysts toward electrochemical hydrogen evolution reaction

Developing low-cost, stable, and robust electrocatalysts for hydrogen evolution reaction (HER) is highly desirable for large-scale application. In this study, a highly efficient electrocatalysts of metal ferrites (MFe₂O₄, M = Co, Ni, Zn, Cu) with superior activity and durability are successfully fabricated on copper substrate through a facile co-precipitation method followed by doctor-blading deposition. The electrocatalytic performance of CoFe₂O₄, NiFe₂O₄, ZnFe₂O₄ and CuFe₂O₄ electrodes for hydrogen evolution reaction is studied in alkaline media using polarization curves and electrochemical impedance spectroscopy (EIS). Among them, CoFe₂O₄ presented the best electrocatalytic activities for HER with extremely low overpotentials of 270 mV (vs. RHE) at a current density of 10 mA cm^?2 in 1 M KOH. The electrocatalytic activity of MFe₂O₄ (M = Co, Ni, Zn, Cu) for HER to generate current density of 10 mA cm^?2 with low overpotential followed the order of CoFe₂O₄ > CuFe₂O₄ > NiFe₂O₄ > ZnFe₂O₄. The highly improved HER performance of CoFe₂O₄ is mainly due to a large number of exposed active sites, high electrical conductivity and low apparent activation energy, which are confirmed by a remarkable electrochemically active surface area (ECSA = 53.17 cm²), Nyquist plots analysis and Arrhenius plots measurement, respectively. Moreover, the CoFe₂O₄ electrode showed outstanding electrocatalytic stability even after 1000 cyclic voltametry tests. These results provide a promising avenue for developing cost-effective and high-efficiency electrocatalysts based on earth-abundant transition metal ferrite as advanced electrodes for large-scale energy conversion processes.