Excellent Electrochemical Properties of Boron-Doped Single-Crystal Diamond

Direct doping of boron-doped diamond can be achieved by adding a gaseous boron source to the feed gas for chemical vapor deposition (CVD), or introducing volatile liquid or solid boron sources via other gases. CVD is a crucial method for the artificial synthesis of diamond.

Doping with boron not only enhances the electrical conductivity of diamond films but also improves their electrochemical properties. Boron-doped diamond exhibits advantages such as low background current, a wide electrochemical potential window, surface inertness against contamination, high electrochemical stability, and good biocompatibility. These characteristics have earned it the reputation of being an optimal electrode material, with broad application prospects in electrochemical sensors, organic matter degradation, supercapacitors, redox catalysis, and other fields.

Boron-doped diamond film electrodes possess a wide electrochemical potential window: the wider the potential window, the higher the oxygen evolution potential (OEP), making it easier for highly oxidizing reaction intermediates to form in the solution without oxygen evolution reactions occurring. Conversely, a narrow electrochemical potential window leads to oxygen evolution side reactions, which affect the production of strong oxidizing free radicals (e.g., hydroxyl radicals, ozone) and reduce current efficiency and energy efficiency.

Boron-doped diamond film electrodes have low background current; therefore, using BDD electrodes results in a higher signal-to-noise ratio compared to traditional electrodes. Additionally, boron-doped diamond film electrodes are resistant to acid and alkali corrosion, offering longer service life and better stability.

The boron doping concentration is a key factor influencing the electrochemical properties of diamond electrodes. Li Haiqing et al. [7] prepared diamond film electrodes with different boron doping concentrations on a tantalum substrate. When the boron mass concentration was 2 g/L, the grain size was the largest, the potential window reached 3.99 V, and the electrode quality was optimal. The oxygen evolution potentials in acidic, salt, and alkaline solutions were 2.11 V, 1.82 V, and 0.86 V respectively, showing a decreasing trend. However, increasing the boron mass concentration led to reduced particle size, a gradual narrowing of the potential window, and deterioration of film quality.

The boron-doped single-crystal diamond produced by CSMH can achieve doping from low concentration to high concentration. It has realized a uniform and controllable concentration and a customizable boron doping process.CSMH uses the MPCVD method to prepare large-sized and high-quality diamonds,and currently has mature products such as diamond heat sinks, diamond wafers, diamond windows,diamond hetero junction integrated composite substrates,etc.