A Tri-Metallic (Mn–Co–Ti) Oxide Photoanode with Improved Photo-Conversion Efficiency

Abstract

In extension to our previous work, studies have been conducted to illustrate the effect of incorporation of Co2O3 on photo-conversion efficiency of Mn2O3–4TiO2 composite thin films. Therefore, the bimetallic crystal [Mn2Ti4(TFA)8(THF)6(OH)4(O)2]⋅0.4THF (1) was mixed with Co(OAc)2 to fabricate Mn2O3–Co2O3–4TiO2 (MCT) thin films via aerosol-assisted chemical vapour deposition (AACVD) method. The thin films were properly characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray (EDX), Atomic Force Microscopy (AFM) and UV-Vis spectroscopy to evaluate their crystalline structure, chemical composition, topography, surface roughness and band gaps. Finally, the films were subjected to record their photo-electrochemical response in terms of Linear Scan Voltammetry (LSV) and Electrochemical Impedance Spectroscopy (EIS) using 0.5 M NaOH electrolyte solution. A photocurrent density of 4.91 mA cm–2 was observed at 0.65 V vs Ag/AgCl/3M KCl with a promising photo conversion efficiency of 2.86%. Furthermore, impedance studies revealed a decrease in charge transfer resistance (Rct) from 123.79 to 56.43 Ω under illumination conditions.