Preparation of a nanoporous CoFe₂O₄/CoMoO₄ composite electrode material and a study on its performance in water electrolysis

In this study, a CoFe₂O₄/CoMoO₄ composite electrode material with a spinel structure (CoFe₂O₄) and a scheelite structure (CoMoO₄) was prepared by a hydrothermal method. The rich valence states and its unique morphological and structural advantages made the CoFe₂O₄/CoMoO₄ composite electrode material play a more effective synergistic catalytic role. Results of the electrochemical characterization showed that CoMoO₄ was attached to the CoFe₂O₄ skeleton structure in the composite electrode in a sheet form. At a current density of 50 mA cm^-2, the hydrogen evolution overpotential was 193 mV and the respective Tafel slope was 100.44 mV dec^-1, while the oxygen evolution overpotential was 319 mV and the corresponding Tafel slope was 70.47 mV dec^-1. At the same time, the overall water decomposition voltage was 1.55 V at a current density of 10 mA cm^-2, and the voltage changed only 11 mV for a 12 h continuous electrolysis, which suggested a good electrocatalytic water decomposition performance.