Preparation And Electro-oxidation Properties Of ATO/SiO₂Macroporous Electrodes

We studied the preparation and electro-oxidation properties of the macroporous materialsin this paper, using SiO₂macroporous material that has been prepared by predecessors in ourgroup as a support, accomplished the preparation and characterization of ATO/SiO₂macroporous electrodes. Meanwhile, ATO/SiO₂macroporous electrodes were used in theelectro-oxidation of organic compounds and water-soluble ligand anion, investigated its electro-oxidation properties. Details of the research as follows:Due to the effects of structure-direction and strong capillarity from the SiO₂macroporousmaterial, SnCl2and SbCl3in solution state were introduced into the SiO₂macroporous material,and then converted into nano-sized Sb-SnO2（ATO） through two-step hydrolysis andsubsequent calcination at high temperature,then we have prepared ATO/SiO₂macroporouscomposite material.The structures of the new materials were characterized by SEM, HRTEMand XRD, and the properties such as specific surface area and conductivity were also measured.The results showed that the nano-ATO chemically deposited on the SiO₂support underwentwell-controlled aggregation and recrystallization to form a sandwich structure with SiO₂nano-layer. Through four times loading of ATO the volume resistance and the specific surface arearespectively reached to be10cm and77m2.g-1. The electrochemical measurements showedthat the macroporous ATO/SiO₂anode has a high oxygen evolution potential in acidicconditons of2.5V.The ATO/SiO₂macroporous electrodes were used in the study of electro-oxidation oforganic compounds.Methyl orange was used to investigate the electro-oxidation properties ofATO/SiO₂macroporous electrodes as well as the degradation mechanism. It was found thatATO/SiO₂macroporous electrodes have good conductivity in aqueous solution and catalyticability to split water, which make methyl orange easily degradable by electro-oxidation. Thedegradation of methyl orange started from the breakage of azo double bond, leaving sodiumbenzene sulfonate and a small amount of aniline derivatives as residue.4-chlorophenol wasused to investigate the electro-oxidation properties of ATO/SiO₂macroporous electrodes as wellas the impact of adding Fe²⁺on the electrocatalytic oxidation. It was found that ATO/SiO₂ macroporous electrodes have the electro-catalysis ability of degradation of4-chlorophenol.Besides, it was also found that Fe²⁺can significantly improve the current efficiency ofATO/SiO₂macroporous electrode in4-chlorophenol solution by promoting the generation ofOH radicals.The ATO/SiO₂macroporous electrodes were used in the study of electro-oxidation ofwater-soluble ligand anion.The new materials have been served as macroporous anodes to studythe electro-catalytic oxidation of complexes containing metal ions such as Fe, Cu and Ni. Thesolid products from the oxidation of the Fe complexes and Ni complexes were identified byXPS to be Fe2O3xH2O and NiO, respectively, while the product from Cu complexes waselementary copper. The measurement of the content of metal in solution by means of atomabsorption indicated that above90%of metal can be recycled from the solution of thecorresponding complex. Through measuring the COD of pure ligands during oxidation it wasfound that CN-、SCN-and EDTA can be degraded to produce less harmful substances, the finalCOD reached to a very low level. Further-step investigations indicated that SCN-can bedesulfurized in the macroporous anode to produce CN-and sulfur. Since both of S2-and SO42-were found in the mixture of the products, it might be implied that a disproportionation reactionof the resulted sulfur had been induced on the surface of nano-ATO probably by strong effect ofpolarization.