Voltammetric and Capacitance Behavior of Optically Transparent Diamond Electrodes in Room-Temperature Ionic Liquids
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2023-11-21 |
| Journal | The Journal of Physical Chemistry C |
| Authors | Fatemehsadat Parvis, G. J. Blanchard, Greg M. Swain |
| Institutions | Michigan State University |
| Citations | 4 |
Abstract
Section titled āAbstractāThe electrochemical working potential window, voltammetric background current, potential-dependent capacitance, and redox activity of boron-doped diamond optically transparent electrodes (BDDOTEs) were evaluated in different room-temperature ionic liquids (RTILs) using cyclic voltammetry and electrochemical impedance spectroscopy. Three 1-alkyl-3-methyl imidazolium tetrafluoroborate ([EMIM][BF4], [BMIM][BF4], and [HMIM][BF4]) and three 1-alkyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI], [BMIM][TFSI], and [HMIM][TFSI]) RTILs were studied. Some measurements were also performed in 1 mol L-1 KCl, for comparison. The goal of this work was to learn about the electrochemical behavior of BDDOTEs in RTILs and how it differs from that in a conventional aqueous electrolyte solution. The working potential window was 4.5 V for all the three RTILs. The potential-dependent capacitance values (Cdl-E) were lower in the different RTILs over the potentials probed, ranging from 3 to 9 Ī¼F cm-2, as compared to 8-16 Ī¼F cm-2 in 1 mol L-1 KCl. The RTIL type exhibited little effect on the working potential window, voltammetric background current, or interfacial capacitance values of the BDDOTEs. The Cdl-E curves were generally flat across the potential range probed or had a slight upward shift with increasing positive potential, which is much different from the bell-shaped curves observed for a Au disk electrode. Interestingly, the BDDOTEs exhibited both semiconducting electronic properties, as evidenced by Mott-Schottky analysis of the capacitance data with an apparent flat band potential in the range of 2-3 V vs Ag QRE, and semimetallic electronic properties, as evidenced by quasi-reversible electron-transfer kinetics for ferrocene and ferrocene derivatives in the bis(trifluoromethylsulfonyl)imide RTILs with the electrodes under depletion conditions. The heterogeneous behavior of the BDDOTEs is attributed to the uneven boron dopant distribution spatially within the film. Comparison studies with glassy carbon electrodes revealed voltammetric background current and capacitance values 5-10Ć larger than the values for the BDDOTEs in the RTILs consistent with a lower density of electronic states in the latter.