Fabrication of a boron-doped nanocrystalline diamond grown on an WC–Co electrode for degradation of phenol
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2022-01-01 |
| Journal | RSC Advances |
| Authors | Tao Zhang, Zhe Xue, Ying Xie, Guodong Huang, Guangpan Peng |
| Institutions | Wuxi Institute of Technology, Shanghai Ocean University |
| Citations | 11 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Boron-Doped Nanocrystalline Diamond on WC-Co for Phenol Degradation
Section titled “Technical Documentation & Analysis: Boron-Doped Nanocrystalline Diamond on WC-Co for Phenol Degradation”Executive Summary
Section titled “Executive Summary”This documentation analyzes the fabrication and performance of nanocrystalline Boron-Doped Diamond (BDD) films deposited on WC-Co substrates for electrochemical oxidation (EO) applications, specifically phenol degradation.
- Material Achievement: Successful deposition of highly uniform, pinhole-free nanocrystalline BDD films (NCD-BDD) with a grain size of 100 nm and a thickness of ~4 µm onto pretreated WC-Co cemented carbide.
- High Conductivity: The resulting WC-Co/BDD electrode exhibits extremely low resistivity (0.2 mΩ cm) and high boron incorporation (up to 3.5 x 1021 cm-3), essential for efficient charge transfer.
- Electrochemical Stability: Demonstrated superior stability compared to conventional substrates (Ti, Si, Nb), achieving a service life exceeding 400 hours in an Accelerated Life Test (ALT) at a high current density (1 A cm-2).
- Wide Potential Window: The electrode maintains a wide electrochemical window of 3.8 V, crucial for generating highly potent hydroxyl radicals (•OH) necessary for Advanced Oxidation Processes (AOPs).
- Application Performance: Achieved high mineralization capacity for concentrated phenol (25 mmol L-1), reducing Chemical Oxygen Demand (COD) from 5795 mg L-1 to 85 mg L-1 with an average current efficiency of 46%.
- Stress Management: The low residual compressive stress (-2.3 GPa) in the NCD-BDD film is cited as a key factor improving film adhesion and extending the overall electrode service life.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Film Type | Nanocrystalline BDD (NCD) | N/A | Deposited via HFCVD |
| Substrate Material | WC-Co (6% Co) | N/A | Cemented Carbide Rods (3 mm diameter) |
| Film Thickness | ~4 | µm | Measured via FE-SEM cross-section |
| Grain Size | ~100 | nm | Observed via FE-SEM |
| Residual Stress | -2.3 | GPa | Calculated compressive stress (Raman) |
| Boron Concentration (Raman) | 3.5 x 1021 | cm-3 | Estimated via 500 cm-1 peak |
| Resistivity (BDD Film) | 0.2 | mΩ cm | Four-point probe measurement |
| Electrochemical Window | 3.8 | V | Range: -1.0 V to 2.8 V vs. Ag/AgCl |
| ALT Service Life | >400 | h | In 3 mol L-1 H2SO4 at 1 A cm-2 |
| Initial COD (Phenol) | 5795 | mg L-1 | 25 mmol L-1 phenol solution |
| Final COD (Phenol) | 85 | mg L-1 | After 43 Ah L-1 charge loading |
| Average Current Efficiency (ICE) | 46 | % | For phenol oxidation |
| HFCVD [B]/[C]gas Ratio | 5000 | ppm | Dynamic boron-doping method |
| Growth Temperature | 850 | °C | Substrate temperature |
Key Methodologies
Section titled “Key Methodologies”The nanocrystalline BDD films were fabricated using a self-made Hot Filament Chemical Vapor Deposition (HFCVD) system.
- Substrate Pretreatment: WC-Co rods (6% Co composition) were subjected to a two-step chemical pretreatment (Murakami’s reagent for 30 min, Caro’s acid for 60 s) to remove the cobalt binder, followed by abrasion with 5 µm commercial diamond powders to create surface defects and enhance nucleation density.
- Reactive Sources: Acetone (C source), trimethyl borate (C3H9BO3) (B source), and excessive hydrogen (H2) were introduced into the HFCVD chamber.
- Boron Doping Control: A dynamic boron-doping method was employed, setting the [B]/[C]gas atomic ratio at a constant 5000 ppm for both nucleation and growth phases.
- Nucleation Parameters (30 min):
- CH4/H2 ratio: 2.0%
- Substrate Temperature: 800 °C
- Filament Temperature: 2000 ± 200 °C
- Pressure: 2 kPa
- Growth Parameters (270 min):
- CH4/H2 ratio: 1.5%
- Substrate Temperature: 850 °C
- Filament Temperature: 2200 ± 200 °C
- Pressure: 2 kPa (maintained low to improve nucleation density and reduce residual stress).
- Electrochemical Testing: Accelerated Life Tests (ALT) were conducted in 3 mol L-1 H2SO4 using a constant current density of 1 A cm-2, monitoring the cell voltage over time.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The research demonstrates the critical role of high-quality, low-stress, heavily doped diamond films for robust electrochemical oxidation. 6CCVD is uniquely positioned to supply the advanced MPCVD materials and customization required to replicate and scale this technology.
| Research Requirement | 6CCVD Solution & Capability | Technical Advantage |
|---|---|---|
| Material: Heavily Boron-Doped Diamond (3.5 x 1021 cm-3) | Heavy Boron-Doped Polycrystalline Diamond (BDD-PCD) | Our BDD-PCD is engineered for ultra-low resistivity (mΩ cm range) and high charge carrier concentration, ensuring maximum efficiency for hydroxyl radical generation and high current density operation. |
| Dimensions: Small 3 mm diameter rods (1 cm2 effective area) | Custom Dimensions & Large-Area Wafers | 6CCVD supplies BDD plates and wafers up to 125 mm in diameter. We offer precision laser cutting and shaping services to produce custom electrode geometries, enabling seamless scale-up from lab-bench rods to industrial prototypes. |
| Thickness Control: Precise 4 µm film thickness | Thickness Control (0.1 µm to 500 µm) | We offer precise control over BDD film thickness, allowing engineers to optimize the diamond layer for cost efficiency, mechanical stability, and specific electrochemical performance requirements. |
| Substrate Integration: Adhesion optimization on non-conventional substrates (WC-Co) | Custom Substrate Processing & Metalization | While the paper used WC-Co, 6CCVD provides BDD deposition on standard substrates (Si, Nb, Ti) and offers custom metalization services (Au, Pt, Pd, Ti, W, Cu) for enhanced electrical contact and bonding layers, crucial for long-term electrode stability. |
| Surface Quality: Need for highly uniform, low-stress films | Advanced Polishing Services | 6CCVD provides polishing services for PCD films to achieve surface roughness (Ra) < 5 nm on inch-size wafers, minimizing defects that could lead to premature failure or corrosion, as observed in the ALT test. |
Engineering Support
Section titled “Engineering Support”6CCVD’s in-house PhD team provides expert consultation on material selection and process optimization for similar Electrochemical Oxidation (EO) and Wastewater Treatment projects. We assist researchers in tailoring diamond film properties—including doping level, grain structure (NCD vs. MCD), and stress profile—to maximize electrode life and current efficiency on challenging substrates.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
WC-Co is applied as the substrate instead of conventional ones, on which nanocrystalline BDD films are deposited by HFCVD. WC-Co/BDD electrode like the standard BDD shows a wide potential window and a good mineralization capacity in phenol.