Structural Optimization Of Boron-Doped Diamond Electrode And Study Of Its Electrochemical Oxidation Products

Boron-doped diamond（BDD）electrode is commonly considered as an ideal anode material for electrochemical oxidation of water treatment due to exceptional advantages of high oxygen evolution potential,and ultra-high electrochemical stability.However,during electrochemical oxidation water treatment,BDD electrodes are prone to generate high concentrations of perchlorate with strong biological toxicity,and the energy consumption of water treatment is too high to meet the practical application standards.Herein,the electrochemical oxidation process of chloride ions on the surface of BDD electrode with different boron doping concentrations was studied,and the electrochemical oxidation efficiency was improved by constructing a three-dimensional foam BDD electrode,thereby reducing the energy cost of water treatment,from the perspective of the composition and macroscopic structure of BDD electrodes.（1）Based on the composition of BDD films,the safety of electrochemical oxidation technology is improved.BDD films with different boron doping concentrations were deposited on Si substrates via hot filament chemical vapor deposition（HFCVD）.The mechanistic effects of boron doping concentration on the types and concentrations of chlorine products at BDD electrodes during the electrochemical oxidation process were explored.The results showed that as the boron doping concentration increased,the grain size of diamond decreased,the oxygen evolution potential slightly shifted negatively,the charge transfer resistance gradually decreased,and the electrochemically active surface area gradually increased accordingly.The minimum energy to generate active chlorine per unit was observed with the doping concentration of 1.23×10²⁰cm^-3,and the corresponding energy consumption and the yields of Cl O₃^-and Cl O₄^-were the lowest,meeting the highest safety standard for electrochemical water treatment.（2）By optimizing the macrostructure of the BDD electrode,the energy consumption of electrochemical oxidation technology to degrade wastewater can be reduced.The Ta foam skeleton was fabricated via 3D printing,followed by HFCVD growth of continuously dense polycrystalline BDD films with good quality.The electrochemical properties and degradation performance of BDD foam and BDD plate electrodes were comparatively investigated.The results showed that the BDD foam electrode exhibited a significantly pronounced electrochemical active surface area and apparent advantages over BDD plate electrodes,whether in different current densities,different initial pollutant concentrations or a high stirring speed.The lowest energy consumption for tetracycline hydrochloride removal was only 0.33 k Wh g^-1.However,it is noted that under stationary conditions,the electrochemical oxidation performance of the BDD foam electrode was slightly lower than that of the BDD plate electrode,presumably attributed to the relatively low utilization of hydroxyl radicals（·OH）generated at the electrochemically active sites inside the foam BDD electrode.