Abstract
Boron-doped diamond (BDD) have attracted increasing attention as a material for electrochemical sensors and biosensors due to its remarkable properties such as its chemical inertness, wide electrochemical potential window, low background current and biocompatibility. Diamond layers are synthesized mainly from a gas phase consisting of carbon, hydrogen, and a dopant source by microwave plasma-assisted chemical vapour deposition (MPACVD). The gas composition during the growth of diamond film has a significant influence on its surface morphology, crystallographic structure, dopant concentration, and superficial non-diamond carbon phases. Thus, the growth conditions of the diamond layer affect the electrochemical properties of the material.
Herein we demonstrate the electrochemical and physicochemical studies of as-grown boron-doped diamond thin-film electrodes, synthesized in a deuterium-rich plasma (BDDD). It is the first report concerning the study of the effect of replacing hydrogen by deuterium during BDD growth. The substitution of hydrogen to deuterium in the gas phase is primarily responsible for the enhanced boron doping and significantly decrease of nondiamond sp2 phase in diamond films. Moreover, the crystallographic structure of BDDD layer is dominated by the (111) configuration while the texture of the BDDH electrode film is oriented along the (220) direction [1].
The proposed boron-doped diamonds synthesized in the deuterium-rich plasma electrodes were revealed to have a higher activity towards [Fe(CN)6]3-/4- and [Ru(NH3)6]2+/3+ redox mediators than BDD electrode grown in hydrogen-rich plasma (BDDH). The peak-to-peak separation recorded on BDDD electrode reaches 60.6 mV, and 59.8 mV in [Fe(CN)6]3-/4- and [Ru(NH3)6]2+/3+ redox couples, respectively. Moreover, in Ru(NH3)62+/3+ solution, the apparent heterogeneous electron transfer rate constant k°app for the BDDD was equal to 5.84·10-3 cm s-1. The BDDD and BDDH electrodes were also used as an electrochemical sensor for the paracetamol detection. BDDD electrode exhibits better sensing performance towards PCM comparing to BDDH electrode. The value of limit of detectionfor the BDDD electrode was 765 nM, whereas for the BDDH was 2510 nM. The better electrocatalytic behavior of the BDDD electrodes may result from the higher amount of electroactive zones on deuterium-terminated diamond strictly related to (111) crystal facets.
Acknowledgement
This work was supported by the Polish National Science Centre [2020/01/0/ST7/00104]. The DS funds of the Faculty of Electronics, Telecommunications, and Informatics of the Gdansk University of Technology are also acknowledged.
Reference:
[1] A. Dettlaff et al., Carbon [In press]. Doi: doi.org/10.1016/j.carbon.2020.11.096.