Insights into the Electrochemical Behavior of Mercury on Graphene/SiC Electrodes

Abstract

Fast and real time detection of Mercury (Hg) in aqueous solutions is a great challenge due to its bio-accumulative character and the detrimental effect on human health of this toxic element. Therefore, development of reliable sensing platforms is highly desirable. Current research is aiming at deep understanding of the electrochemical response of epitaxial graphene to Mercury exposure. By performing cyclic voltammetry and chronoamperometry measurements as well as density functional theory calculations, we elucidate the nature of Hg-involved oxidation-reduction reactions at the graphene electrode and shed light on the early stages of Hg electrodeposition. The obtained critical information of Hg behavior will be helpful for the design and processing of novel graphene-based sensors.

Epitaxial Graphene on 4H-SiC (0001) as a Versatile Platform for Materials Growth: Mini-Review

“…In addition to the dc magnetron sputtering technique, we also employed electrochemical deposition to investigate the early nucleation stages of several selected metals (lead, copper, and mercury) on epitaxial graphene [50][51][52]. Pb and Hg have been of interest related to toxic metal detection, while Cu attracts a lot of attention as a promising catalyst.…”

“…The knowledge of redox reactions on pristine epitaxial graphene enables the identification of the deposition potential window and can thus be considered as a starting point for further investigation of metal deposition kinetics. The redox behaviour of mercury is quite complicated and slow, since both mercury reduction (Hg 2+ + 1e − = Hg 1+ + 1e − = Hg 0 ) and oxidation (Hg 0 − 1e − = Hg 1+ − 1e − = Hg 2+ ) reactions occur in two steps, which is evidenced by the presence of two reduction and two oxidation peaks (Figure 11a-c) [51]. It was found that the copper electrodeposition on pristine monolayer epitaxial graphene on SiC proceeds via one-step bi-electronic reduction avoiding Cu 1+ intermediate involvement during the first cycle (Figure 11d) [52].…”

Electrochemical Deposition of Copper on Epitaxial Graphene

“…where t and t max are the elapsed and maximum times, respectively; j inst , j prog and j max are the current densities for instantaneous and progressive nucleation, and maximum current density, respectively. The initial kinetics of the copper electrodeposition obeys the three-dimensional instantaneous nucleation model (Figure 3b), which is likely the general mechanism for the metal's electrodeposition on epitaxial graphene monolayer, since the same growth kinetics was observed during electrodeposition of lead [101] and mercury [80]. This implies that metal electrodeposition on epitaxial graphene happens on a limited number of active sites.…”

“…Due to evident advantages over other graphene family materials (namely, its large surface area free of functional groups, high quality of monolayer graphene, thickness uniformity, wide potential window, high signal-to-noise ratio, transfer-free technology, and direct sublimation growth without precursors [75][76][77]), epitaxial graphene has been tested with promising results for the real-time detection of Pb 2+ ions in aqueous solutions (with a detection limit far below the WHO's permissible level for lead in drinking water) through performing square-wave anodic stripping voltammetry and response-recovery measurements [78,79]. Inspired by this, we have recently extended our activities beyond lead detection to include the investigation of the electrochemical behavior of the Hg 2+ /Hg 0 redox couple at the epitaxial graphene working electrode [80]; now, we are aiming to elucidate the nature of the copper electroreduction at the epitaxial graphene surface. Since this issue is very poorly investigated in the literature, in-depth investigations at an atomistic level are still needed to deal with the problem.…”

Symmetrical Derivative of Anthrone as a Novel Receptor for Mercury Ions: Enhanced Performance of Modified Screen-Printed Electrode

“…Bernalte et al [18], used screen-printed gold electrodes for the determination of mercury by square wave anodic stripping voltammetry, while Hallam et al [19,20] reported electrochemical sensing of Cr(VI) with graphite screenprinted electrodes; for a full overview, see reference. Some recent reports on electrochemical sensors for mercury determinations include works of Raril and Manjunatha [21], Mikhail Vagin and Yakimova [22], Eksin et al [23], and Ganjali et al [24].…”