The Preparation Of Spinel Co-base Compounds Nanomaterials And The Applications In Catalysis

With the increasement of the earth's population and the rapid development of modern economy,we are facing huge challenges about environmental pollution and energy crisis.Co-based spinel oxides which has high catalytic activity,corrosion resistant in alkaline solution,and are relatively inexpensive,are widely used in photocatalyst and electrocatalytic oxygen evolution.In this article,spinel Co₃O₄ and CoFe₂O₄ three-dimensional nanochain network catalysts were synthesized by a facile hydrothermal method for photocatalytic degradation of dye and electrocatalytic oxygen evolution reaction.CuO/Co₃O₄ coaxial heterostructures were prepared by hydrothermal methods.Themorphology of composite strongly affects the efficiency of photodegradation.Compared with CuO NRs,CuO/Co₃O₄ nanosheets,and Co₃O₄nanoflowers,the synthesized CuO/Co₃O₄ coaxial heterostructures catalysts showed high photocatalytic efficiency for the degradation of MB under full spectrum solar light irradiation.According to the PL spectra and UV-Vis absorption spectra,the enhanced photocatalytic performance of CuO/Co₃O₄ composite can mainly be explained by the electronhole?e-h?charge separation.The band structure of the heterostructures permits the transfer of electrons from CB of Co₃O₄ to CB of CuO and transfer of holes from VB of CuO to VB of Co₃O₄.Therefore,the recombination of electron-hole pairs will be hindered and the photocatalytic property would be improved.A facile chemical reduction process and hydrothermal treatment is developed for preparation of CoFe₂O₄ 3D nanochain networks which could be excellent catalyst for anode of OER.The morphology of CoFe₂O₄ 3D nanochain networks were characterized by scanning electron microscopy and transmission electron microscopy.Spinel-type structure is determined by XRD.The composition and chemical state are determined by Raman measurement and XPS Spectra.Vibrating sample magnetometer have been used to characterize their microstructures and magnetic properties.Finally the water electrolysis for oxygen evolution activity of the catalyst have been characterized by electrochemical workstation in alkaline.Results show that CoFe₂O₄ 3D nanochain networks have high catalytic activity and good electrocatalytic stability.According to the calculation,the Co nanoparticles have the moderate d-band center position which indicates the optimal adsorption energies.Co nanoparticles are the best among the three transition metals and alloy.CoFe₂O₄,which can create a surface with a high oxygen coverage.This kind of surface may in turn establish optimal oxygen adsorption energy,thus lead to maximum in activity for oxygen evolution.Due to its large active surface area,stable structure,high stability and high catalytic efficiency,there is great potential for practical application.