Electrochemical Reaction Mechanism And Applications Based On Interfacial Engineering Of Boron-doped Diamond

Known as the "ultimate semiconductor",diamond is an important ultra-wide-bandgap semiconductor material.With excellent optical,thermal and electrical properties,diamond is highly demanded in fields such as high-tech industry,national defense,and medical and health care.Boron-doped diamond(BDD)obtained by p-type doping in diamond plays an important role in electrochemistry because of its properties such as wide electrochemical window,low background current,and weak surface adsorption.However,the intrinsic inertness of BDD surface affected the electrochemical performance.In order to adapt to the practical applications,developing new methods to improve the properties of surface and interface is quietly urgent.In this thesis,we take BDD as the research object,and combine various surface/interface modification techniques to study the electrochemical reaction mechanism and applications at BDD interface.The main research contents and conclusions are as follows:1.We provide an overview of the structures and properties of diamond and boron-doped diamond materials,as well as methods for the fabrication of surface microstructures.In specific,we review the d-band model of transition metals,hydrophobic/water interfacial properties,and the current research states of electrochemical applications of boron-doped diamond.2.We prepare the patterned-BDD by high-speed nanosecond laser engraving.The patterned-BDD effectively improves the electrochemical degradation rate of methyl orange,and the final color removal rate is close to 100%.Furthermore,we develop a method for fabricating non-enzymatic glucose sensing electrode based on BDD by high-speed nanosecond laser engraving and pulsed electrodeposition.The electrode consists of patterned-BDD and densely packed periodic copper nanoflakes(CuNFs)arrays,that enables fast,precise,and high signal-to-noise detection of trace glucose.Outstanding performances that contain high sensitivity of 21 19 μA cm-2 mM-1,ultrafast response the of<1 s,and low detection limit of 0.2 μM are experimentally demonstrated.Furthermore,the electrode exhibits excellent cyclicality(500 cycles)and anti-interference ability,and maintains 90%of its initial detection activity after being stored in air for>8 months.3.We explain the improved glucose sensing on CuNFs/BDD based on the d-band model.The d-band of Cu promotes the catalytic oxidation of glucose and the patterned-BDD ensures a high signal-to-noise ratio and the high stability of CuNFs/BDD.The surface with multi-level micro-nanostructures accelerates the mass and electron transfer at the interface.4.We realize ECL reactions of Ru(bpy)3Cl2-TPrA and Ru(bpy)3Cl2-K2C2O4 on BDD surface.Nanobubbles are formed on BDD by in situ electrochemical reactions,which greatly enhance the ECL reaction of Ru(bpy)3Cl2-TPrA.5.We analyze the mechanism of the enhanced ECL reaction on nanobubbles/BDD surface.The large electric field at the bubble/solution interface reduces the reaction activation energy,and the low dielectric constant promotes the pre-equilibrium between the excited 3MLCT state and the 3MC state of Ru(bpy)32+to shift to the 3MLCT state,thereby enhancing the radiation transition efficiency.In summary,we develop methods for preparing the patterned-BDD,CuNFs/BDD and nanobubbles/BDD electrodes.The above electrodes facilitate the electrochemical methyl orange degradation,glucose detection,and electrochemiluminescence reactions,respectively.Combined with the d-band theory,the principles are analyzed for high-efficiency glucose sensing on CuNFs/BDD.The mechanisms are discussed for enhanced ECL reaction on nanobubbles/BDD surface in combination with the hydrophobic/water interface properties.