The electrodeposition of mercury from aqueous Hg22+ ion-containing acid solutions on smooth and columnar-structured platinum electrodes

Abstract

The electrodeposition of Hg on polycrystalline smooth and columnar structured Pt (cs-Pt) substrates was comparatively studied in acid solution at 298 K applying potentiodynamic techniques. The topography of both types of Pt electrodes was characterized by scanning tunneling microscopy. The use of cs-Pt substrates provides information about surface processes which are not easily detected on conventional smooth Pt. At moderate and high potential scan rates Hg electrodeposition under mass transport control on cs-Pt yields a non-equilibrium complex deposit consisting of 2d and 3d Hg domains, and Pt-Hg alloy coexisting with bare Pt domains at intercolumnar voids. The dynamics of these domains approaching equilibrium can be followed by conventional voltammetry. The kinetics of Hg penetration into bulk Pt results from a Hg atom shift to a position underlying the first layer of Pt atoms followed by a diffusion-controlled penetration into bulk Pt. The Hg atom diffusion coefficient into bulk Pt results in D 3 2 × 10 −17 cm 2 s −1 .

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

“…Furthermore, Radhi A closer look at the asymmetry of the oxidation and reduction peaks (see Figure 2b,c) enables assigning the components O 1 at 0.236 V and O 2 at 0.258 V for the oxidation process to two well-defined steps (Hg 0 − 1e − = Hg 1+ − 1e − = Hg 2+ ), as well as R 1 at 0.09 V and R 2 at 0.128 V components for the reduction process to two one-electron steps (Hg 2+ + 1e − = Hg 1+ + 1e − = Hg 0 ), respectively. Similar voltammetry response has also been observed for Hg at the partially oxidized graphene/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) nanocomposite film-modified electrode [66], Hg at the Pt electrode [64], and Hg at the activated carbon modified glassy carbon electrode [67].…”

“…The 0.1 mM Hg 2+ solution shows a reduction peak R 1 ranging from 0 V to +0.18 V, followed by the corresponding oxidation wave in the potential range from +0.19 V to +0.42 V, which can be attributed to Hg redox reactions, see dark blue colored curve in Figure 1. The voltammogram also shows additional features (R 2 plateau in the range −0.29 V to −0.41 V and R 3 peak located at −0.52 V) possibly associated with overpotential deposition (opd) of Hg and oxygen electrosorption reactions [64]. The intense split oxidation peak with two distinguishable components (O 1 and O 2 ) related to Hg stripping is indicative of a two-step oxidation reaction at the electrode surface; see the inset in Figure 1 [65].…”

Preparation of Metal Amalgam Electrodes and Their Selective Electrocatalytic CO2 Reduction for Formate Production

“…For the purpose, solid amalgam electrodes are explored to produce formate by an electrochemical CO 2 reduction [16]. It was shown that mercury thin layers can be electrodeposited on metal foils such as Pt, Pd, Ir, Cu and Ag [17][18][19]. The electrochemical CO 2 reduction was performed with Cu amalgam at 1 atm and the total current density of −200 mA•cm −2 with the formate efficiency of 12.9% was reported without the information about the applied potential [20].…”

Modeling of Current Distribution on Smooth and Columnar Platinum Structures

“…These electrodes behave as rough polycrystalline (pc) platinum, with a nearly constant distribution of crystallographic orientation, regardless of the magnitude of roughness, which covers the 1 to 10 3 range. [12,13] Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) usually produce images of the surface morphology and the overall structure of the metal deposits. However, they do not work in real time since they only analyze the final electrode structures after the end of growth.…”