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6CCVD Research

Porous BiVO4/Boron-Doped Diamond Heterojunction Photoanode with Enhanced Photoelectrochemical Activity

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2022-08-16
JournalMolecules
AuthorsJiangtao Huang, Aiyun Meng, Zongyan Zhang, Guanjie Ma, Yuhao Long
InstitutionsShenzhen University, Shenzhen Technology University
Citations9
AnalysisFull AI Review Included

Executive Summary

Section titled “Executive Summary”

This research successfully fabricated a novel porous n-BiVO4/p-BDD (Boron-Doped Diamond) heterojunction photoanode, designed to maximize photoelectrochemical (PEC) efficiency for water splitting and pollutant degradation.

  • Novel Structure: The photoanode incorporates masses of ultra-micro p-n heterojunction electrodes and porous n-type Bismuth Vanadate (BiVO4) films deposited on a p-type BDD substrate.
  • Optimal Performance: The optimized sample (M30, 30 min BiVO4 deposition) achieved a peak current density of 1.8 mA/cm2 at 1.23 VRHE under AM 1.5 irradiation.
  • Pollutant Degradation: The M30 photoanode demonstrated superior degradation activity, achieving 45.1% removal of Tetracycline Hydrochloride (TCH) in just 10 minutes (rate constant k = 0.057 min-1).
  • Enhanced Mechanism: The high PEC activity is attributed to the built-in electric field at the ultra-micro p-n junction, which drives efficient charge separation and significantly lowers the carrier recombination rate.
  • Material Advantages: The BDD substrate provides exceptional chemical robustness, high thermal/electrical conductivity, and a wide potential window, making the device highly stable for practical applications.
  • Electronic Structure: Mott-Schottky analysis confirmed the successful formation of the p-n junction, with BiVO4 (n-type, ND ~ 1018 cm-3) and BDD (p-type, NA ~ 1018 cm-3).

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Peak Current Density (J)1.8mA/cm2M30 sample, at 1.23 VRHE, AM 1.5
Optimal BiVO4 Deposition Time (Td)30minSample M30
TCH Degradation Rate Constant (k)0.057min-1M30 sample, 10 min test
TCH Removal Efficiency45.1%M30 sample, 10 min test
BiVO4 Band Gap (Eg)2.5 ± 0.1eVDirect-gap semiconductor
BiVO4 Carrier Density (ND)1018cm-3n-type semiconductor
BDD Carrier Density (NA)1018cm-3p-type semiconductor
BiVO4 Flat Band Potential (Efb)0.25VRHEMott-Schottky analysis
BDD Flat Band Potential (Efb)3.24VRHEMott-Schottky analysis
BiVO4 Annealing Temperature500°CPost-sputtering crystallization
BiVO4 Annealing Duration120minAtmospheric condition
BDD Raman Peak1331cm-1Crystalline diamond confirmation
BiVO4 Raman Peak (V-O stretch)823cm-1Monoclinic BiVO4 confirmation
PEC Electrolyte0.1 M Na2SO4N/AAqueous solution
Light Irradiation100mW/cm2AM 1.5 standard

Key Methodologies

Section titled “Key Methodologies”
  1. BDD Substrate Growth: Conductive silicon (Si) substrates were seeded with diamond nanoparticles, followed by deposition of the BDD film using Hot Filament Chemical Vapor Deposition (HFCVD) in a CH4/H2/TMB gas mixture.
  2. Amorphous V-BiVO4 Deposition: An amorphous V-rich BiVO4 (V-BiVO4) film was deposited onto the BDD using a Magnetron Sputtering (MS) system, utilizing Vanadium (V) and BiVO4 targets in an O2/Ar gas mixture.
  3. Thickness Tuning: The thickness of the V-BiVO4 film was controlled by varying the sputtering duration (Td) between 15 min and 75 min (M15 to M75).
  4. Vanadium Addition: 0.3 mL of vanadium (V) solution (prepared from vanadyl acetylacetonate in DMSO) was drop-cast onto the V-BiVO4/BDD films.
  5. Crystallization Annealing: The films were annealed at 500 °C for 120 min under atmospheric conditions to form the monoclinic BiVO4 crystalline phase.
  6. Purification: Excess V2O5 was removed using a 1 M NaOH solution to yield the final porous BiVO4/BDD heterojunction photoanodes.
  7. Electrochemical Testing: PEC performance was evaluated using a CHI 760E workstation under AM 1.5 irradiation (100 mW/cm2) in 0.1 M Na2SO4 solution. Mott-Schottky tests were conducted at 1000 Hz.

Commercial Applications

Section titled “Commercial Applications”
  • Industrial Wastewater Treatment: High-speed, efficient photoelectrocatalytic degradation of persistent organic pollutants (e.g., antibiotics like TCH) and dyes, leveraging the high oxidative power of BDD-based anodes.
  • Solar Fuel Production: PEC water splitting devices for generating clean hydrogen (H2), utilizing the visible-light absorption capability of BiVO4 and the charge separation efficiency of the p-n heterojunction.
  • Environmental Management Systems: Development of robust, long-lifetime photoanodes for continuous operation in harsh chemical environments due to the chemical inertness and stability of the BDD substrate.
  • Advanced Sensor Technology: The ultra-micro electrode array structure inherent in the porous BiVO4/BDD interface can be adapted for high-sensitivity electrochemical or photoelectrochemical sensing applications.
  • Self-Cleaning Materials: Integration into surfaces requiring photocatalytic self-cleaning or antifouling properties under ambient light conditions.
View Original Abstract

Constructing heterojunction is an attractive strategy for promoting photoelectrochemical (PEC) performance in water splitting and organic pollutant degradation. Herein, a novel porous BiVO4/Boron-doped Diamond (BiVO4/BDD) heterojunction photoanode containing masses of ultra-micro electrodes was successfully fabricated with an n-type BiVO4 film coated on a p-type BDD substrate by magnetron sputtering (MS). The surface structures of BiVO4 could be adjusted by changing the duration of deposition (Td). The morphologies, phase structures, electronic structures, and chemical compositions of the photoanodes were systematically characterized and analyzed. The best PEC activity with the highest current density of 1.8 mA/cm2 at 1.23 VRHE was achieved when Td was 30 min, and the sample showed the highest degradation efficiency towards tetracycline hydrochloride degradation (TCH) as well. The enhanced PEC performance was ascribed to the excellent charge transport efficiency as well as a lower carrier recombination rate, which benefited from the formation of BiVO4/BDD ultra-micro p-n heterojunction photoelectrodes and the porous structures of BiVO4. These novel photoanodes were expected to be employed in the practical PEC applications of energy regeneration and environmental management in the future.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2022 - Heterojunction photoanode of SnO2 and Mo-Doped BiVO4 for boosting photoelectrochemical performance and tetracycline hydrochloride degradation [Crossref]
  2. 2021 - Stable unbiased photo-electrochemical overall water splitting exceeding 3% efficiency via covalent triazine framework/metal oxide hybrid photoelectrodes [Crossref]
  3. 2014 - Semiconductor heterojunction photocatalysts: Design, construction, and photocatalytic performances [Crossref]
  4. 2020 - Tunable photo-electrochemistry of patterned TiO2/BDD heterojunctions [Crossref]
  5. 2016 - Charge separation in TiO2/BDD heterojunction thin film for enhanced photoelectrochemical performance [Crossref]
  6. 2019 - Use of boron-doped diamond electrodes in electro-organic synthesis [Crossref]
  7. 2019 - Conductive diamond: Synthesis, properties, and electrochemical applications [Crossref]
  8. 2021 - Photoelectrocatalytic degradation of glyphosate on titanium dioxide synthesized by sol-gel/spin-coating on boron doped diamond (TiO2/BDD) as a photoanode [Crossref]
  9. 2022 - Enhanced visible-light-driven photoelectrochemical activity in nitrogen-doped TiO2/boron-doped diamond heterojunction electrodes [Crossref]

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