Structural, morphological, electrocatalytic activity and photocurrent properties of electrochemically deposited FeS₂ thin films

Iron pyrite (FeS₂) thin films have been deposited onto indium doped tin oxide coated glass substrate using two sulphur anion sources such as thiourea [(NH₂)₂CS] and sodium thiosulfate [Na₂S₂O₃] by electrochemical deposition method. The profilometer analysis shows that roughness of FeS₂ thin films obtained low for (NH₂)₂CS than the Na₂S₂O₃ as an anion sources. The X-ray diffraction analysis confirms that as-deposited FeS₂ thin films shows cubic system with (200) plane preferential orientation for using (NH₂)₂CS. When Na₂S₂O₃ is used it results in a cubic system (200) along with hexagonal (201) of FeS reflection peak signifying a mixed phase. The optical studies of the thin films deposited using (NH₂)₂CS shows the bandgap at 0.98 eV, while the bandgap for Na₂S₂O₃ was 0.92 V. Atomic force microscopy images shows a crack free and densely packed morphology of FeS₂ thin films obtained for both anion sources. The electrochemical impedance spectra study of FeS₂ thin film exposed that less of charge transfer resistance and fine conductivity was obtained from the (NH₂)₂CS than Na₂S₂O₃ as a sulfur source. The photocurrent study of as-deposited thin films shows that a significant by enhanced photocurrent response for (NH₂)₂CS compared to Na₂S₂O₃ used thin films. The electrocatalytic activity of as deposited FeS₂ thin films shows that better I⁻/I₃⁻ redox couple when investigated by the cyclic voltammetry. The as-deposited FeS₂ thin films obtained from the (NH₂)₂CS as an anion source is capable of to substituting the for platinum electrode.