Electrochemistry of metal adlayers on metal chalcogenides

Abstract

Electrodeposition of metal adlayers on semiconductor metal chalcogenides (CdSe, CdS, PbTe, PbSe, PbS, Bi 2 Te 3 ) is reviewed. Cathodic underpotential deposition of metal adlayer on metal chalcogenide is the electrochemically irreversible surface limited reaction. The irreversibility of the upd increases in the row from tellurides to selenides and further to sulfides. The underpotential shift on chalcogenide nanoparticles increases with particle size. Metal upd on chalcogenides is applied as a means of measurement of electroactive surface area of chalcogenide electrodes. The method is especially advantageous for multicomponent systems with other component not supporting upd, such as CdSe-TiO 2 , CdSe-ZnO. Differences of voltammetric profiles of Pb upd on Bi 2 Te 3 and Te are applied for detection of Bi 2 Te 3 surface contamination by elemental tellurium. The further tasks in the electrochemistry of metal adlayers are their incorporation as interlayers in layered chalcogenides and electrodeposition of superlattices.

Electrophoretically-Deposited CdSe Quantum Dot Films for Electrochromic Displays and Smart Windows

“…However, the open-circuit recovery time is much longer, around 8 s for 180 and 340 nm films, reaching 12 s for 550 nm-thick film. The open circuit bleaching recovery is likely caused by effect of oxidant traces (e.g., O 2 ) in electrolyte , or processes on CdSe QD surface leading to formation of Cd atoms or Cd–Cd dimmers. ,− We believe that the same reason causes suppression of anodic peaks in cyclic voltammetry at slow scan rates (Figure a). In order to elucidate the role of acceptors, we simulated their influence on cyclic voltammetry, assuming the EC cat mechanism, which comprises an electrochemical stage (1) followed by regeneration of the initial (“oxidized” and uncharged) QD state in the irreversible catalytic reaction : …”

“…The QDs in EPD films demonstrated constant electrochromic response upon the applied potential for at least 60 s. At a longer time scale, we observed reversible induced background absorption (SI Figure S7). This background effect may be caused by surface Cd 2+ ions reduction to Cd atoms under prolonged negative polarization. − …”

Electrochemistry of bismuth interlayers in (Bi2)m(Bi2Te3)n superlattice

“…The irreversibility originates from evacuation of the reaction product, which is a slow process, while on a short time scale, the charge transfer in reaction ( 1) is reversible, similarly to the charge transfer in the earlier [21,36] examined reaction (1) in Bi upd on gold. Reversibility of charge transfer in upd manifests itself by adsorption capacitance in the Faradaic branch of equivalent electric circuit [34,36]. The corresponding circuit element C p was clearly disclosed in the anodic bismuth interlayer dissolution by PDEIS data analysis.…”

“…In a and b, the negative scan was reversed immediately after Bi upd into anodically created slits; c and d additionally show cathodic deposition and anodic oxidation of metallic bismuth deposition into the electrochemically created slits, presents a critical hindrance to application of stationary impedance spectroscopy for examination of these processes. This kind of objects is appropriate for examination with nonstationary EIS [33,34].…”

Materials interacting with inorganic selenium from the perspective of electrochemical sensing

“…This process is thermodynamically facilitated; therefore, it occurs at potentials lower than the potential needed for bulk electrodeposition. When the UPD-formed monolayer covers the substrate surface, the deposition potential must be increased to keep deposition of selenium on the formed selenium monolayer 68 . UPD of different species, including selenium, was investigated by the research team of Tedd Lister.…”