Iron–manganese–titanium (1 : 1 : 2) oxide composite thin films for improved photocurrent efficiency

Abstract

In continuation of our previous studies on the photoelectrochemical (PEC) properties of titanium-based composite oxide thin films, an effort was made to develop thin films of the 1 : 1 : 2 iron–manganese–titanium oxide composite, Fe₂MnTi₃O₁₀–MnTiO₃, using Fe(OAc)₂ and a bimetallic manganese–titanium complex, [Mn₂Ti₄(TFA)₈(THF)₆(OH)₄(O)₂]·0.4THF (1), where OAc = acetato, TFA = trifluoroacetato, and THF = tetrahydrofuran by the aerosol-assisted chemical vapour deposition (AACVD) technique. The thin films after their proper characterization with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Mössbauer spectroscopy, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), energy-dispersive X-ray (EDX) spectroscopy, UV-Vis spectrophotometery and photoluminescence (PL) spectroscopy were tested for their potential applications for the photoelectrochemical oxidation of water. The PEC results revealed that a photocurrent density (J_light) of 1.88 mA cm⁻² was obtained at a low potential of 0.20 V vs. Ag/AgCl/3MKCl inferring a promising photo-conversion efficiency of 1.56%. These observations were further endorsed by electrochemical impedance spectroscopic (EIS) studies in terms of charge transportation and its recombination time. Furthermore, the Mott–Schottky plot indicated a flat band potential of −1.0 V vs. Ag/AgCl.