Reversibility‐Dependent Photovoltammetric Behavior of Electroactive Compounds on a CdS–Graphene Hybrid Film Electrode

Abstract

Photovoltammetric behaviors of irreversible, quasi-reversible and reversible electrochemical systems represented by 2,4-dichlorophenol (DCP), hydroquinone (HQ) and K [Fe(CN) ], respectively, were investigated on a CdS-graphene hybrid film electrode. The cyclic voltammetric (CV) curves of HQ and K [Fe(CN) ] showing a pair of redox peaks became sigmoidal in shape under visible light irradiation. In contrast, the CV curve shape of DCP showing an oxidation peak was not changed under photoirradiation, although the oxidation peak current was enhanced by the photoelectrocatalysis. Thus, the reversibility-dependent photovoltammetric behaviors were observed. Furthermore, it was demonstrated that the photovoltammetric curve shapes were not changed by pH and intensity of light source, but were tunable with scan rate and concentration of reactants depending on the reversibility of the electrochemical reactions.

Photovoltammetry of p-Phenylenediamine Mediated by Hexacyanoferrate Immobilized on CdS-Graphene Nanocomposites

“…Interestingly, when the HCF/CdS-G electrode is irradiated with light, the CV curve becomes sigmoidal in shape, accompanied by dramatic enhancement in both anodic and cathodic currents (curve d of Figure 3A). This is in accordance with the previous observation for phovoltammetric behavior of HCF solution on CdS-G electrode, 13 indicating the electron transfer between the immobilized HCF and CdS-G electrode. The appearance of limiting current can be attributed to the participation of photogenerated electrons in the redox reaction of HCF, 13 demonstrating the high photoelectrocatalytic activity of CdS-G electrode toward Fe III /Fe II couple in HCF.…”

“…The appearance of limiting current means that the amount of immobilized HCF on the photoelectrode surface is large enough to consume photogenerated carriers. 13 On the other hand, in presence of PPD, electrooxidized PPD can be reduced to PPD by photogenerated electrons and forms an electrochemical-photochemical cycle of PPD reaction. 12 Moreover, some PPD molecules can be oxidized by HCF(III) to form diimine, which contributes to enhanced anodic limiting current.…”

“…12 Moreover, reversibility-dependent photovoltammetric behaviors of different electrochemical reaction systems have been observed on CdS-G electrode. 13 Nevertheless, the sensing performance of the proposed photovoltammetric method by utilizing the limiting current of photovoltammetric response as detection signal for quantitative determination is difficult because the analytes at low concentrations are unable to consume the photogenerated carriers efficiently. Thus, in the present work, we explored the introduction of a redox mediator which could quickly consume photogenerated carriers for improving the photovoltammetric sensing performance.…”

Silver Chloride/Ferricyanide-Based Quasi-Reference Electrode for Potentiometric Sensing Applications

“…[Fe(CN) 6 ] 3-/4serves as a mediator system in assessing AOA/OA of solid-phase objects in contact hybrid potentiometric method (CHPM) [8][9][10][11]; • [Fe(CN) 6 ] 3-/4is used as a redox probe to study processes in cyclic voltammetry [12][13][14][15][16] and electrochemical impedance spectroscopy [15][16][17]; • [Fe(CN) 6 ] 3-/4is used in bio- [18,19], immuno- [20] and aptasensors [21].…”