Preparation And Study Of Cobalt Molybdenum Oxide Electrode For Water Splitting In Alkaline Electrolyte

In the electrocatalytic water splitting field,mixed metal oxides have received strong attention due to their excellence performance.The microscopic morphology of the catalyst has an important influence on its electrochemical catalytic performance.Through the design of the microscopic morphology of mixed metal oxides,it is possible to prepare a low-cost,high-performance catalyst for water splitting.In this paper,CoMoO₄ and its mixed materials with Co₃O₄ were used as the research object,a novel foam nickel-base cobalt-molybdenum metal oxide coating electrode was prepared by using hydrothermal reaction.We use the field emission scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,energy dispersive X-ray spectroscopy?EDX?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS??Raman?spectrum characterization of the electrode surface morphology,elemental composition and valence,crystal structure.In this paper,electrochemical impedance spectroscopy?EIS?,Tafel slope,linear sweep polarization curve?LSV?,cyclic voltammetry?CV?,electrochemical active area?ECSA?,I-t curves and so on to analyze the electrochemical properties of the electrode.In this paper,the optimal hydrothermal conditions of CoMoO₄ were explored through the morphology design of CoMoO₄.The electrocatalytic hydrogen evolution performance of the prepared electrode was the best when using polyethylene glycol-400 as solvent,1:1 molar ratio of Co and Mo,a reaction temperature of 200oC and the reaction time of 20 h during the hydrothermal process of synthesizing CoMoO₄.The CoMoO₄ and Co₃O₄ hybrid materials were firstly applied to the field of bi-functional water splitting.By the two-step hydrothermal method,self-assembled honeycomb-like pore structures containing Co₃O₄ nanowires coated on two-dimensional?2D?CoMoO₄ nanosheets arrays grown on nickel foam?denoted as Co₃O₄/CoMoO₄/NF?was synthesized.The electric double-layer capacitance of electrode is more than 1.5 times the sum of the two control group electrodes.The charge transfer resistance obtained by the EIS spectrum of CoMoO₄/Co₃O₄/NF is also only 20%of the CoMoO₄ nanosheets.The CoMoO₄/Co₃O₄/NF electrode has excellent electrocatalytic activity that requires the overpotential of 10 mA·cm^-2 in an alkaline medium relative to the hydrogen evolution reaction?HER?and the oxygen evolution reaction?OER?with only 143 mV and 244 mV,much better than the control group CoMoO₄ nanosheets electrode,Co₃O₄ nanowires electrode and bare nickel foam electrode,close to and even beyond the commercial precious metal electrode.In addition,the voltage for bi-functional water splitting at 10 mA·cm^-2 only required 1.61V and had good stability over 30 h during the electrolysis period.The research of this paper shows that CoMoO₄ nanosheets electrode and the CoMoO₄/Co₃O₄/NF electrode has good application prospects in the field of electrocatalytic water splitting.