Study On The Preparation,Modification And Application Of Boron-Doped Diamond Film

As an excellent electrode material,Boron-Doped Diamond film electrode was used for electrochemical oxidation treatment of wastewater.Compared with traditional electrode materials for electrochemical oxidation,BDD film electrode has excellent electrochemical performance,such as wide electrochemical potential window,high oxygen evolution over-potential,low background current and good reversibility.In the wastewater treatment process,BDD film electrode has the advantage of degradation of wide range,high current efficiency,acid and alkali resistance,low adsorption properties and excellent catalytic activity.At the same time,BDD film is also an excellent electrode substrate material,which can realize the immobilization of Ti O2 with good photo-catalytic properties.In the process of photo-catalysis,the suspended TiO2 is easy to agglomerate,difficult to separate,easy to lose activity and difficult to recover.These problems can be easily solved by the immobilization of TiO2.The main purpose of this paper is to prepare BDD film electrode with large area,high quality,good electrochemical performance,excellent performance in degradation of simulated dye wastewater and TiO2 modified BDD composite electrode material with p-n heterojunction structure and good interface.BDD film was synthesized by MPCVD method.NanorodsTiO2 were synthesized on BDD film substrate by hydrothermal method.The degradation of simulated dye wastewater was further studied after encapsulation of electrode materials.The main contents and results of this paper were shown as followings.(1)BDD film was synthesized on(100)single crystal silicon substrates with Methane,Hydrogen and Diborane as gas source by MPCVD method.Through further characterization,the resistivity of the thin film is lower,which is 2.84×10-3 ?·cm.As p-type semiconductor,the hole concentration of BDD material is 1.03×1019 cm-3,the mobility is 214 cm2/v·s.Microstructure observation can be found that the BDD film is polycrystalline,the grain size distribution is below 10 ?m,and the film thickness is about 12 ?m.The characteristics of the film is high diamond content,excellent grade.The cyclic voltammetry test results show that the electrochemical potential window of BDD thin film electrode is wider.Acidic,neutral and alkaline conditions were respectively 3.5 V,4.5 V and 3 V,and the oxygen evolution over-potential of acidic and neutral conditions reached 2.3~2.5 V.(2)TiO2 modified BDD composite material were prepared by hydrothermal method using tetrabutyl titanate as raw material,ultra pure water as solvent and hydrochloric acid as catalyst.Firstly,the optimum conditions for the preparation of TiO2 modified single-crystal diamond were studied by adding different content of tetrabutyl titanate.The result was that TiO2 nanorods with uniform and compact density could be grown when the content of tetrabutyl titanate was 1 mL.According to this result,the TiO2/BDD composite material with p-n heterojunction structure was prepared.The morphology of TiO2 is nanobeam by aggregation of nanorods.The nanorodsTiO2 are uniform and dense,and the crystal form is rutile phase,which is close to the BDD film.(3)Degradation of simulated dye wastewater by BDD electrode and TiO2/BDD composite electrode.The concentration of Na2SO4 is 2 g/L as the supporting electrolyte and the current density is 70 mA/cm2.In the alkaline environment,the degradation of methylene blue dye wastewater is the best by using BDD electrode.On this basis,the degradation of reactive brilliant red X-3B was studied using TiO2/BDD composite electrode after optimizing the structure.Due to the introduction of TiO2,the electrode material with p-n hetero structure has been formed.Comparison of electrochemical oxidation of BDD electrode,photoelectric catalysis of composite electrode further enhance the degradation rate of reactive brilliant red.