Electrochemical Properties and Chemical Oxygen Demand Depending on the Thickness of Boron-Doped Diamond

At a Glance

Metadata	Details
Publication Date	2020-11-16
Journal	Coatings
Authors	Chang Song, Mi Young You, Jae‐Myung Lee, Dae‐Seung Cho, Pung Keun Song
Institutions	Pusan National University
Citations	3
Analysis	Full AI Review Included

Technical Documentation & Analysis: Boron-Doped Diamond for Electrochemical Water Treatment

Executive Summary

This analysis focuses on the successful fabrication and evaluation of Boron-Doped Diamond (BDD) films for high-efficiency electrochemical wastewater treatment, providing a clear pathway for 6CCVD material solutions.

Material Achievement: BDD films were successfully deposited using Hot-Filament Chemical Vapor Deposition (HFCVD) with cost-effective liquid precursors (Acetone and Trimethyl Borate).
Constant Deposition Rate: A stable deposition rate of 100 nm/h was maintained, allowing precise control over film thickness, yielding 1.1 µm (12 h) and 5.6 µm (60 h) films.
Electrochemical Performance: Boron doping (approx. 11,400 ppm) imparted necessary electrochemical properties, with the potential window slightly increasing with film thickness.
Superior Application Efficacy: BDD electrodes demonstrated exceptional performance in Chemical Oxygen Demand (COD) removal, achieving an average degradation rate of 90%.
Competitive Advantage: BDD significantly outperformed conventional IrO₂ electrodes, which achieved only a 47.35% COD removal rate under identical testing conditions.
6CCVD Value Proposition: 6CCVD specializes in high-quality MPCVD BDD, offering superior control over doping uniformity, thickness, and large-area deposition necessary for scaling this critical wastewater treatment technology.

Technical Specifications

The following hard data points were extracted from the experimental results and deposition parameters:

Parameter	Value	Unit	Context
Deposition Method	HFCVD	N/A	Hot-Filament Chemical Vapor Deposition
Deposition Rate	100	nm/h	Constant rate observed across 12 h and 60 h runs
BDD Thickness (12 h)	1.1 ± 0.2	µm	Measured via cross-sectional FE-SEM
BDD Thickness (60 h)	5.6 ± 0.5	µm	Measured via cross-sectional FE-SEM
Boron Doping Concentration	11,400	ppm	Calculated based on precursor flow rate (approx. 1% doping)
Filament Input Power	16	kW	Optimized HFCVD power setting
Deposition Pressure	4000	Pa	Process pressure during growth
Filament-Susceptor Distance	10	mm	Optimized working distance
COD Removal Rate (BDD Avg.)	90	%	High removal rate for nonbiodegradable contaminants
COD Removal Rate (IrO₂ Ref.)	47.35	%	Performance of conventional reference electrode
Electrolysis Voltage	5	V	Constant voltage used for COD analysis

Key Methodologies

The BDD films were fabricated using a controlled HFCVD process optimized for cost-effective precursor utilization and uniform deposition.

Substrate Preparation: Silicon wafers (for thickness measurement) and Niobium (Nb) plates (for electrochemical testing) were cleaned using ethanol and ultrasonication.
Seeding Process: Substrates were pretreated by applying a 1:1 weight ratio mixture of 500 nm diamond powder and glycerin, followed by rubbing and ethanol washing to ensure high nucleation density.
CVD Setup: A custom HFCVD chamber utilized twelve rows of Tantalum (Ta) filaments (320 mm length, 0.7 mm diameter) spaced 20 mm apart.
Precursor System: Acetone (carbon source) and Trimethyl Borate (TMB, boron source) solutions were introduced via a bubbling system using Hydrogen (H₂) as the carrier gas.
Precursor Temperature Control: Both liquid precursors were immersed in an antifreeze solution maintained precisely at 0 °C using a thermostat to ensure consistent vapor pressure and stable delivery of reactants.
Deposition Parameters: Key process parameters were fixed: 16 kW filament power, 4000 Pa pressure, and a 10 mm filament-susceptor distance. The susceptor was rotated at 1 rpm for uniform film growth.
Electrochemical Testing: Cyclic Voltammetry (CV) was performed using a potentiostat in 0.5 M Na₂SO₄ solution to measure the potential window and catalytic activity (using 50 mM K₃Fe(CN)₆/K₄Fe(CN)₆).
Application Testing: COD removal efficiency was measured using farm wastewater samples under a constant 5 V electrolysis voltage, comparing BDD performance against a standard IrO₂ electrode.

6CCVD Solutions & Capabilities

The research successfully validates BDD as a superior material for advanced electrochemical oxidation in wastewater treatment. 6CCVD’s expertise in high-quality, scalable MPCVD diamond is perfectly positioned to meet and exceed the requirements of this application, offering enhanced material control and larger dimensions necessary for industrial deployment.

Applicable Materials

To replicate and extend this research, 6CCVD recommends the following materials:

Material Specification	6CCVD Offering	Relevance to Research
Boron-Doped Polycrystalline Diamond (BDD)	Heavy Boron Doped PCD	Essential for high electrochemical activity and hydroxyl radical generation (required 11,400 ppm doping). 6CCVD offers precise, tunable doping levels.
Substrate Material	Custom Substrates (Nb, Si, Mo, W)	The paper utilized Niobium (Nb) and Silicon (Si). 6CCVD provides BDD deposition on various conductive and insulating substrates up to 10 mm thick.
Film Thickness	PCD Films (0.1 µm - 500 µm)	The tested films were 1.1 µm and 5.6 µm. 6CCVD can supply BDD films across this entire range, enabling optimization for long-term industrial electrode life (up to 500 µm).

Customization Potential

The transition from laboratory-scale HFCVD to industrial application requires robust, large-area electrodes. 6CCVD’s capabilities directly address these scaling challenges:

Large-Area Electrodes: While the paper used small 900 mm² samples, 6CCVD offers PCD plates/wafers up to 125 mm in diameter, crucial for high-throughput industrial wastewater reactors.
Precision Thickness Control: 6CCVD’s MPCVD process offers superior control over film uniformity and thickness compared to HFCVD, ensuring consistent electrochemical performance across large areas.
Custom Metalization: For robust electrical contacts on BDD anodes, 6CCVD provides in-house metalization services, including Ti/Pt/Au, W, or Cu layers, ensuring low-resistance ohmic contacts necessary for efficient electrolysis.
Surface Finish: Although not the primary focus of the paper, 6CCVD offers advanced polishing (Ra < 5 nm for inch-size PCD), which can be critical for flow dynamics and minimizing fouling in industrial water treatment systems.

Engineering Support

The high efficiency of BDD relies on optimizing the material properties (doping level, grain size, and surface termination) to maximize the generation of strong oxidizing agents (OH⁻, O₃).

6CCVD’s in-house PhD team provides expert consultation to assist researchers and engineers in:

Doping Optimization: Fine-tuning boron concentration to maximize the potential window and catalytic activity for specific Electrochemical Wastewater Treatment projects.
Material Selection: Advising on the optimal substrate and diamond grade (PCD vs. SCD) based on required current density and operational lifetime.
Electrode Design: Supporting the design and fabrication of complex electrode geometries using our advanced laser cutting and metalization capabilities.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

In this study, boron-doped diamond (BDD) film was deposited by hot-filament chemical vapor deposition (HFCVD) using acetone as the carbon source and trimethyl borate (TMB) as the boron source with the aim of lowering the manufacturing cost of BDD electrodes. The BDD film was deposited for 12 and 60 h to observe changes in the morphological behavior of the film as well as subsequent changes in the electrochemical properties. The morphology of the BDD film was not affected by the deposition time, but the thickness increased with increasing deposition time. As the deposition time increased, the deposition rate of the BDD film did not increase or decrease; rather, it remained constant at 100 nm/h. As the thickness of the BDD film increased, an increase in the potential window was observed. On the other hand, no distinct change was observed in the electrochemical activation and catalytic activity depending on the thickness, and there were not many differences. Chemical oxygen demand (COD) was measured to determine the practical applicability of the deposited BDD film. Unlike the potential window, the COD removal rate was almost the same and was not affected by the increase in the thickness of the BDD film. Both films under the two deposition conditions showed a high removal rate of 90% on average. This study confirms that BDD electrodes are much more useful for water treatment than the existing electrodes.

Tech Support

Original Source

DOI: https://doi.org/10.3390/coatings10111097

References

2012 - Boron doped diamond electrodes based on porous Ti substrates [Crossref]
2018 - Depth treatment of coal-chemical engineering wastewater by a cost-effective sequential heterogeneous Fenton and biodegradation process [Crossref]
2018 - Biodegradation of Emerging Organic Micropollutants in Nonconventional Biological Wastewater Treatment: A Critical Review [Crossref]
2009 - Electrochemical disinfection of biologically treated wastewater from small treatment systems by using boron-doped diamond (BDD) electrodes—Contribution for direct reuse of domestic wastewater [Crossref]
2012 - Synthesis and Temperature-dependent Electrochemical Properties of Boron-doped Diamond Electrodes on Titanium
2000 - Boron doped diamond (BDD)-layers on titanium substrates as electrodes in applied electrochemistry [Crossref]
2006 - Impact of grain-dependent boron uptake on the electrochemical and electrical properties of polycrystalline boron doped diamond electrodes [Crossref]
2007 - Studies on electrochemical treatment of wastewater contaminated with organotin compounds [Crossref]
2008 - Primary biodegradation of ionic liquid cations, identification of degradation products of 1-methyl-3-octylimidazolium chloride and electrochemical wastewater treatment of poorly biodegradable compounds [Crossref]