Preparation And Application Of Complex Oxide Coated Nano-electrode For The Oxidation Of Pollutants

Electrochemical catalyze and oxidation of organic pollutants is one of the best and most efficient treatments and searching for the right electrode to apply in the environment treatment is popular in the recent years. Surface microstructure and modified species are two key factors according to the electrode performance. Study of the internal relation between the factors and other characters is a significative preparation of environment protecting and applied electrode products.In this paper, preparation and application of different complex metal oxide modified Ti electrodes were studied. Noble metal (Pt, Pd) and rare earth elements (La, Ce, Eu, Sm) were respectively added into SnO₂+Sb₂O₅ by different preparation methods. SEM, XRD, CV and etc. were introduced to investigate surface microstructure, electrochemical characters, serve life and electrochemical oxidation effect and the conclusions were listed below.The average crystal lattice of the SnO₂+Sb₂O₅/Ti which was prepared by sol-gel and dip-pull method is found to be 20nm, indicated a significantly increase of the electrode surface area value. The noble metal mixed SnO₂+Sb-2O₅/Ti is 25nm (Pt) and 35nm (Pd), and the rare earth mixed SnO₂+Sb₂O-5/Ti also have a nano-structure surface as the average crystal lattice size is below 50nm.The oxygen evolution potential of micro-SnO₂+Sb₂O₅/Ti is lower than nano-SnO₂+Sb₂O₅/Ti in H₂SO₄, Na₂SO₄, NaOH medium, especially in Na₂SO₄ solution. The noble metal mixed SnO₂+Sb₂O₅/Ti is a bit lower than nano-SnO₂+Sb₂O₅/Ti in H₂SO₄ and Na2SC>4 solution and the rare earth mixed SnO₂+Sb₂O₅/Ti is higher than nano-SnO₂+Sb₂O₅/Ti in NaOH medium.The transfer coefficient 6 of oxidation at anode raised with the average crystal lattice size shrank from micro to nano.βof the noble metal mixed SnO₂+Sb₂O₅/Ti and the rare earth mixed SnO₂+Sb₂O₅/Ti is higher than nano-SnO₂+Sb₂O₅/Ti.The serve life of nano-SnO₂+Sb₂O₅/Ti greatly extended to 19 hours that is three times than the micro-SnO₂+Sb₂O-5/Ti. And the noble metal mixed SnO₂+Sb₂O₅/Ti and the rare earth mixed SnO₂+Sb₂O₅/Ti respectively extended to 23 hours and 30 hours. A significant electrochemical oscillation of formaldehyde on nano-SnO₂+Sb₂O₅/Ti was discovered. Further study indicated the electrochemical oscillation behavior is related with electrode surface area value, modified species, concentration of support electrolyte and formaldehyde, experiment temperature and etc. Similar electrochemical oscillation is also received on noble metal mixed SnO₂+Sb₂O₅/Ti and the rare earth mixed SnO₂+Sb₂O₅/Ti have good electrocatalytic property towards aniline.Electrochemical oxidation of phenol, aniline and benzoic acid on eight complex metal oxide electrodes were studied. The results showed that the total oxidation capability of nano-SnO₂+Sb₂O₅/Ti, nearly the same as noble metal mixed SnO₂+Sb₂O₅/Ti, is five times of micro-SnO₂+Sb₂O₅/Ti while the rare earth mixed SnO₂+Sb₂O₅/Ti increased 40%-60% according to the nano-SnO₂+Sb₂O₅/Ti. Phenol is mainly oxided into CO₂ and H₂O on nano-SnO₂+Sb₂O₅/Ti and rare earth mixed SnO₂+Sb₂O₅/Ti, and mainly turned into intermediate on noble metal mixed SnO₂+Sb₂O₅/Ti. Polyaniline film will cover the surface of noble metal mixed SnO₂+Sb₂O₅/Ti and benzoic acid is mainly turned into intermediate on SnO₂+Sb₂O₅+PtO/Ti.Impact factors of electrochemical characters of complex metal oxide electrodes were studied. The preparation methods were considered to be the most important factor of the electrode surface microstructure. The sol-gel and dip-pull method leads to a fine uniform nano surface. The mixed species can affect the average crystal lattice size, improve the combination between metal oxide layer and Ti, raise the serve life of the electrode. Furthermore, the reduction of the average crystal lattice size will increase the surface area value and the oxidation capability.