Preparation And Catalytic Application Of Copper Hexacyanocobaltate And Nickel Zinc Chromium Composite Metal Oxide

Copper hexacyanocobaltate was electro-deposited at amino-graphene coated indium-tin-oxide glass by cyclic voltammetry to form multifunctional heterogeneous catalyst（Cu Co G/ITO）,which was confirmed by FE-SEM,XRD,FT-IR and electrochemistry techniques.The cubic copper hexacyanocobaltate（Cu₃[Co（CN）₆]₂）was evenly distributed at the graphene surface.A novel photo-electro-Fenton like system was established using Cu Co G/ITO as an air diffusion electrode,in which hydrogen peroxide（H₂O₂）and hydroxyl radical（·OH）could be simultaneously photo-electro-catalytically generated at Cu Co G/ITO by O₂ reduction and Fenton reaction.The study showed that the productive rate of·OH could reached to 70.5μmol h^-1 at-0.8 V with 300 W visible light irradiation in p H 7.0,0.1 M Na₂HPO₄.Moreover,Levofloxacin（LEV）could be degraded at Cu Co G/ITO during photo-electro-Fenton like process with a first-order kinetic constants of 0.49 h^-1.Polyaspartic acid modifying magentic graphene（MGA）was firstly prepared with promising magnetic separation and metal ions uptake properties.Ni（Zn）Cr layered double hydroxides coating magnetic-graphene composites（Ni（Zn）/Cr-LDHs/MGA）were synthesized by co-precipitation method using spent electroplating wastewaters,which were further calcined to form layered double oxides（Ni（Zn）/Cr-LDOs/MGA）.The resulting materials were carefully examined by FE-SEM,XRD,FT-IR and electrochemical techniques.A large number of spherical particles（Fe₃O₄）and flocculent（polyaspartic acid）adhered to the graphene surface;Ni（Zn）/Cr-LDHs with layered structure were uniformly distributed at the surface of MGA;Ni（Zn）/Cr-LDOs/MGA displayed porous structures.The electro-catalysis of the materials towards oxygen evolution reaction（OER）was investigated by various electrochemical methods in 1 M KOH（p H～13.6）.Ni/Cr-LDO/MGA formed at 500℃showed an excellent electro-catalysis for OER at lower over-potential of 0.41 V and Tafel slope of 110 m V dec^-1 with highly current density of 10 m A cm^-2.Moreover,Ni/Cr-LDO/MGA formed at 500℃showed good catalytic stability with current retention of 93%over long period of 50000 s.These demonstrated that the spent electroplating wastewaters could be reused to fabricating value-added catalyst on OER.