Skip to content
6CCVD Research

Effect of Surface Oxygen on the Wettability and Electrochemical Properties of Boron-Doped Nanocrystalline Diamond Electrodes in Room-Temperature Ionic Liquids

At a Glance

Section titled ā€œAt a Glanceā€
MetadataDetails
Publication Date2020-04-29
JournalLangmuir
AuthorsKirti Bhardwaj, Fatemehsadat Parvis, Yufeng Wang, G. J. Blanchard, Greg M. Swain
InstitutionsMichigan State University
Citations14

Abstract

Section titled ā€œAbstractā€

This paper reports on how the surface chemistry of boron-doped nanocrystalline diamond (BDD) thin-film electrodes (H vs O) affects the wettability and electrochemical properties in two room-temperature ionic liquids (RTILs): [BMIM][PF<sub>6</sub>] and [HMIM][PF<sub>6</sub>]. Comparative measurements were made in 0.5 mol L<sup>-1</sup> H<sub>2</sub>SO<sub>4</sub>. The BDD electrodes were modified by microwave or radio-frequency (RF) plasma treatment in H<sub>2</sub> (H-BDD), Ar (Ar-BDD), or O<sub>2</sub> (O-BDD). These modifications produced low-, medium-, and high-oxygen surface coverages. Atomic O/C ratios, as determined by X-ray photoelectron spectroscopy (XPS), were 0.01 for H-BDD, 0.08 for Ar-BDD, and 0.17 for O-BDD. The static contact angle of ultrapure water on the modified electrodes decreased from 110Ā° (H-BDD) to 41Ā° (O-BDD) with increasing surface oxygen coverage, as expected as the surface becomes more hydrophilic. Interestingly, the opposite trend was seen for both RTILs as the contact angle increased from 20Ā° (H-BDD) to 50Ā° (O-BDD) with increasing surface oxygen coverage. The cyclic voltammetric background current and potential-dependent capacitance in both RTILs were largest for BDD electrodes with the lowest O/C ratio (H-BDD) and smallest contact angle. Slightly larger voltammetric background currents and capacitance were observed in [HMIM][PF<sub>6</sub>] than in [BMIM][PF<sub>6</sub>]. Capacitance values ranged from 8 to 16 Ī¼F cm<sup>-2</sup> over the potential range for H-BDD and from 4 to 6 Ī¼F cm<sup>-2</sup> for O-BDD. The opposite trend was observed in H<sub>2</sub>SO<sub>4</sub> as the voltammetric background current and capacitance were largest for BDD electrodes with the highest O/C ratio (O-BDD) and smallest contact angle. In summary, reducing the surface oxygen on BDD electrodes increases the wettability to two RTILs and this increases the voltammetric background current and capacitance.

Tech Support

Section titled ā€œTech Supportā€

Original Source

Section titled ā€œOriginal Sourceā€

References

Section titled ā€œReferencesā€
  1. 2004 - Electroanalytical Chemistry

Reads Similar to This

Electrochemical degradation of surfactants in domestic wastewater using a DiaCleanĀ® cell equipped with a boron-doped diamond electrode Correction - Radtke et al. Plasma Treatments and Light Extraction from Fluorinated CVD-Grown (400) Single Crystal Diamond Nanopillars. C 2020, 6, 37 Boron-Doped Diamond Electrocatalyst for Enhanced Anodic H2O2 Production