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

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 cm(2)) 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 sp(2) impurities along with heavy boron doping (>10(21) 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 (similar to 3.3 V) and low double-layer capacitance (<4 mu F 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 Delta E-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, 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.

Automated summary

In this study, three heteroepitaxial single-crystal boron-doped diamond (SC-BDD) electrodes were fabricated and characterized. The SC-BDD electrodes exhibited large area and high dopant concentration, with different surface morphologies due to growth on different substrates. The electrodes showed high conductivity and metal-like behavior, and demonstrated excellent electrochemical response and resistance to fouling.