Interfacial studies of Cu2O/TiO2 junction deposited at different electropotentials

Abstract

Based on the simplistic two-step preparation method, a Cu2O/TiO2 junction was synthesized by electrodepositing a Cuprous Oxide layer on Titanium Oxide thin films at different deposition potentials. The thin films and junction were characterized for their structural, morphological, optical, and electrical properties using X-ray diffraction, Scanning Electron Microscopy, UV–visible spectroscopy, and Electrochemical Impedance Spectroscopy. The XRD analysis of the Cu2O/TiO2 junction indicated no sharp diffraction peaks of TiO2, only Cu2O peaks were observed. The Scanning Electron Microscopy also demonstrated that the Cuprous Oxide thin films possessed three-sided pyramidal structures on their surface. The band gaps of Cu2O and TiO2 thin films were calculated as 2.2 eV and 3.3 eV respectively by using Tauc’s plots. Electrochemical impedance spectroscopy revealed reduced interfacial charge transfer resistance and a boost in charge carrier generation in fabricated junctions (grown at −0.6 V). The flat band potentials and carrier concentrations of the fabricated thin films and their junction were calculated using Mott-Schottky analysis. Meanwhile, charge transfer resistance, solution resistance, constant phase element, and other circuit parameters of the electrochemical cell were studied using Nyquist plots.

Keywords

• Electrochemical impedance spectroscopy
• Cuprous oxide
• Titanium oxide
• Electrodeposition