Research On Fabrication And Electrochemical Properties Of Highly Boron-doped Si/BDD Thin-Film Electrode

With the development of the living standard of the people, the requirement of the water quality for people become up and up. Whereas the industrial wastewater and the water pollution are becoming increasingly serious, so we would find a better way to solve these problems. In present society, "energy conservation and pollution reduction" has become the major themes of our times, while the wastewater contains many nonbiodegradable organic contaminants, especially the high concentration of aromatic compounds and the highly toxic compounds which are difficult to directly be degraded. So the electrochemical catalysis is coming. The electrochemical treatment of such wastes depends on a great many factors, and, in particular, the nature of the electrode material, that the electrocatalysis ability , current efficiency and the life of electrode is depend on , several electrodes in use today have many deficiencies, such as surface fouling and deactivation ,only selective oxidation and a limited service life. BDD is a new electrode material that has received great attention recently. Because it possesses several technologically important characteristics such as an inert surface with low adsorption properties, remarkable corrosion stability, even in strong acidic media, and an extremely wide potential window in aqueous and non-aqueous electrolytes. Comparing with other electrode materials, it possesses the better physical and chemical properties.Owing to these properties diamond electrodes meet the requirements for a wide range of electrochemical underlying applications. This article mainly discusses and summarize the recently researched results and problem concerning the application of BDD electrode to electrochemical such as waster water treatment. In this paper ,boron-doped diamond film on the heavily doped silicon substrate prepared by the microwave plasma chemical vapor deposition and the electrochemical properties of BDD were characterized by resistivity measurement by 4-point probe method ,SEM, Raman spectroscopy and electrochemistry working station,the resistivity of diamond films is 10^-2Ω·cm, meanwhile, the quality of the diamond film was deteriorated with the increasing of boron doped. The electrochemical properties of the electrode were investigated using cyclic voltammetry, the results showed that Si/BDD electrode had a very wide potential window and very low background current ,comparing with Pt electrode; and as electrode leader for BDD was jointed to the conducting substrate(high doped-Si),more work area and lower cost of BDD could get. In electrolyte including Ferri/Ferrocyanide, the electrochemical reaction carrying out on the surface was a diffusion-controlled reaction , with good quasi- reversibility and excellent chemical stability. Studies of the oxidation of organic compounds showed that,compared with Pt electrode, the diamond electrode could oxidate phenol ,and the process of oxidation was very simple and complete. In the experiment of electrochemical catalysis of the model wastewater, highly boron-doped diamond film, which will probably replace the traditional electrode materials, is a potentially promising and green electrode material.For restoring the damaged BDD electrode, the surface planarization of BDD, which would have a profound effect on the distribution of surface current density of BDD, should be essentially studied. But diamond with the super-high hardness is difficult to process and fabricated. For improving the surface planarization of BDD ,a suitable material with high etching rate of diamond need to be found. In chapter four a certain thickness of polycrystalline diamond films were synthesized in silicon by microwave plasma chemical vapor deposition(MPCVD) and then under the hydrogen plasma and the graphitization effect of dissolved carbon material-Fe, Co ,the corrosive action of Fe, Co on the surface of diamond film was investigated. The cleaned surface was observed with scanning electron microscopy under a secondary electron mode. The corroded surface of the diamond films were characterized by Raman spectroscopy. The results indicated that the corrosive effect of these dissolved carbon metals on the diamond films is clear, with Fe having the largest effect, after the etching of the diamond films, the non-diamond-like carbon left on the diamond films surface are cleaning for the further processing, the high quality which can be comparable with the original quality of diamond is obtained.