HPHT Boron-Doped Diamond Electrodes Nitrogen Getter
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Solution Overview
Problem
High-pressure high-temperature (HPHT) boron doped diamond electrodes face challenges due to uncontrolled atmospheric nitrogen incorporation, leading to disrupted electrical properties and reduced conductivity, unlike CVD boron doped diamond electrodes with similar boron doping levels.
Innovation Solution
The synthesis of synthetic HPHT diamond electrodes with a substitutional boron concentration between 1×10^20 and 5×10^21 atoms/cm^3 and a nitrogen concentration of no more than 10^19 atoms/cm^3, using a nitrogen getter material to minimize nitrogen compensation effects, and forming these electrodes into various structures such as microelectrodes or compacted bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HPHT method is used to synthesize boron doped diamond electrodes, then production cost and time are reduced compared to CVD, but nitrogen impurities are incorporated into the diamond material disrupting electrical conductivity
Solution Approach 1:
A nitrogen getter material is introduced as an intermediary substance during HPHT synthesis. This getter material selectively binds with nitrogen impurities in the reaction zone, preventing nitrogen from incorporating into the diamond crystal lattice while allowing boron to be incorporated substitutionally. The getter acts as a mediator that removes the harmful nitrogen without interfering with the desired boron doping process.
Solution Approach 2:
The nitrogen getter material extracts and removes nitrogen impurities from the HPHT reaction zone during diamond synthesis. By selectively binding with nitrogen, the getter extracts this harmful impurity from the system before it can be incorporated into the diamond structure, thereby producing high-purity boron doped diamond with improved electrical conductivity.
2Reliability
If high boron concentration is used to achieve metal-like conductivity, then electrical conductivity is improved, but nitrogen compensation effect increases reducing net conductivity
Solution Approach 1:
The nitrogen getter material performs preliminary anti-action by removing nitrogen impurities before they can compensate for boron dopants in the diamond lattice. By preemptively binding with nitrogen during synthesis, the getter prevents the formation of compensated boron-nitrogen pairs that would reduce electrical conductivity, thereby preserving the metal-like conductivity achieved through high boron doping.
Solution Approach 2:
The nitrogen getter serves as an intermediary that selectively interacts with nitrogen impurities, preventing nitrogen from compensating boron dopants. This intermediary substance allows high boron concentrations to be incorporated into the diamond lattice while blocking the harmful compensation effect, thus maintaining high electrical conductivity.
3Reliability
If CVD method is used to produce diamond electrodes, then electrical conductivity and inertness are maintained, but surface area is limited and production is expensive
Solution Approach 1:
The HPHT synthesis method inherently produces diamond materials with porous or high-surface-area structures. By combining this with nitrogen removal using a getter, the invention creates electrodes that maintain the electrical conductivity of dense diamond while utilizing the high surface area of porous structures for enhanced electrochemical performance and reduced cost compared to CVD.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in HPHT diamond electrodes with improved electrical conductivity and metal-like conductivity characteristics, maintaining a low nitrogen compensation effect and minimizing non-diamond carbon presence, thus enhancing their electrochemical performance and reversibility.
Implementation Method 1
the boron must be substitutionally doped, at high enough density; in other words, it must replace a carbon atom in the diamond crystal lattice
Implementation Method 2
when boron concentration in diamond is greater than 1×10^20 atoms cm^-3, the acceptor levels overlap with the valence band as the diamond undergoes the Mott transition to demonstrate metal-like conductivity
Implementation Method 3
The electronic level of the nitrogen donor is too deep in the band gap to give useful electrical conductivity. Nitrogen is known to reduce the electrical properties of boron doped diamond because, as a deep level, 1.7 eV, n-type dopant, it leads to charge compensation with boron
Implementation Method 4
Boron doped diamond (BDD) electrodes are made by the chemical vapour deposition (CVD) of BDD onto a suitable substrate
Implementation Method 5
The synthesis of boron-containing diamonds by a high pressure, high temperature (HPHT) solvent/catalyst method
Data Source
AI summary
An electrode comprising synthetic high-pressure high-temperature diamond material, the diamond material comprising a substitutional boron concentration of between 1×1020 and 5×1021 atoms/cm3 and a nitrogen concentration of no more than 1019 atoms/cm3. The electrode has a ΔE3/4-1/4 as measured with respect to a saturated calomel reference electrode in an aqueous solution containing 0.1 M KNO3 and 1 mM of Ru(NH3)63+ selected any of less than 70 mV, less than 68 mV, less than 66 mV, and less than 64 mV, and/or a peak to peak separation ΔEp as measured with respect to a saturated calomel reference electrode in an aqueous solution containing 0.1 M KNO3 and 1 mM of Ru(NH3)63+ selected any of less than 70 mV, less than 68 mV, less than 66 mV, and less than 64 mV.