Cathodic and anodic deposition of FeS2 thin films and their application in electrochemical reduction and amperometric sensing of H2O2

A comparative study has been made on the performance of electrochemical reduction and amperometric sensing of H2O2 by the cathodically and anodically deposited orthorhombic FeS2 thin films. Individual chronoamperometric depositions were carried out on indium doped tin oxide (ITO) coated glass substrates from an aqueous solution containing Mohr's salt (FeSO4(NH4)2SO4·6H2O) and Na2S2O3 with optimized molar concentrations. Cyclic voltammetry and linear sweep voltammetry were carried out to determine the exact reduction and oxidation potentials for the two systems. Structural, morphological, compositional, optical and electrical characterizations were carried out using X-ray diffraction (XRD) technique, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), UV–vis spectroscopy and four-probe and two-probe current–voltage measurements, respectively. It was established from XRD that both cathodic and anodic depositions were orthorhombic (Fe:S = 1:2) in nature. Cathodic films were found to have interlinked fiber like morphology, while the anodic films showed flake-like and rough morphology. It was also observed that the amperometric sensing mechanism was highly dependent on the morphology of the deposited films.

Cathodic and anodic depositions of FeS2 thin films have been carried out chronoamperometrically and a detailed study on the electrochemical behavior for the deposition has been done using cyclic voltammetry and linear sweep voltammetry. It has been found that morphology plays an important role toward to electrocatalytic properties of the deposited semiconductors. The porosity in the anodic film helps in better electrocatalytic and chronoamperometric sensing, might be due to the large surface-to-volume ratio. The smaller value of Michaelis–Menten constant for the anodic film indicates that the immobilized FeS2 has higher catalytic activity and affinity toward H2O2.Figure optionsDownload as PowerPoint slideHighlights
► Cathodic and anodic depositions of FeS2 thin films have been carried out chronoamperometrically.
► Detailed study on the electrochemical behavior for the deposition has been done using CV and LSV.
► Comparative studies have been made on the morphology and electrocatalytic properties of the films.
► Porosity in the anodic film helps in better electrocatalytic and chronoamperometric sensing.
► Smaller Kmapp value for anodic film indicates that immobilized FeS2 has higher catalytic activity and affinity toward H2O2.