Heavily boron-doped diamond grown on scalable heteroepitaxial quasi-substrates: A promising single crystal material for electrochemical sensing applications

Liu, Z.; Baluchová, S.; Frota Sartori, A.; Li, Z.; Gonzalez Garcia, Y.; Schreck, Matthias; Buijnsters, J.G.

doi:10.1016/j.carbon.2022.10.023

Heavily boron-doped diamond grown on scalable heteroepitaxial quasi-substrates

Title

Heavily boron-doped diamond grown on scalable heteroepitaxial quasi-substrates: A promising single crystal material for electrochemical sensing applications

Author

Liu, Z. (TU Delft Micro and Nano Engineering)
Baluchová, S. (TU Delft Micro and Nano Engineering)
Frota Sartori, A. (TU Delft Micro and Nano Engineering)
Li, Z. (TU Delft Team Arjan Mol)
Gonzalez Garcia, Y. (TU Delft Team Yaiza Gonzalez Garcia)
Schreck, Matthias (Universität Augsburg)
Buijnsters, J.G. (TU Delft Micro and Nano Engineering)

Date

2023

Abstract

In this work, three distinct heteroepitaxial single-crystal boron-doped diamond (SC-BDD) electrodes were fabricated and subjected to detailed surface analysis and electrochemical characterization. Specifically, the heteroepitaxy approach allowed to synthesize large-area (1 cm²) and heavily-doped (100)-oriented SC-BDD electrodes. Their single-crystal nature and crystal orientation were confirmed by X-ray diffraction, while scanning electron and atomic force microscopies revealed marked variations in surface morphology resulting from their growth on respective on-axis and off-axis substrates. Further, absence of sp² impurities along with heavy boron doping (>10²¹ cm⁻³) was demonstrated by Raman spectroscopy and Mott-Schottky analysis, respectively. Cyclic voltammetry (CV) in a 0.1 M KNO₃ solution revealed wide potential windows (∼3.3 V) and low double-layer capacitance (<4 μF cm⁻²) of the SC-BDD electrodes. Their highly conductive, ‘metal-like’ nature was confirmed by CV with [Ru(NH₃)₆]^3+/2+ probe manifesting near-reversible redox response with ΔE_p approaching 0.059 V. The same probe was used to record scanning electrochemical micrographs, which clearly demonstrated homogeneously distributed electrochemical activity of the heteroepitaxial SC-BDD electrodes. Minor differences in their electrochemical performance, presumably resulting from the somewhat different morphological features, were only unveiled during CV with surface sensitive compounds [Fe(CN)₆]^3−/4− and dopamine. The latter was also used to show the possibility of applying herein developed heteroepitaxial SC-BDD electrodes for electrochemical sensing, whereas experiments with anthraquinone-2,6-disulfonate revealed their enhanced resistance to fouling. All in all, heteroepitaxial SC-BDD represents a highly attractive electrode material which can, owing to the fabrication strategy, easily overcome size limitation, currently preventing broader use of single crystal diamond electrodes in electrochemical applications.