Photoelectrocatalytic activity of Mn2O3–TiO2 composite thin films engendered from a trinuclear molecular complex

Abstract

Newly synthesized trinuclear bimetallic precursor [Mn2Ti(μ3−O) (TFA)6 (THF)3] (1) (where TFA = trifluoroacetato and THF = tetrahydrofuran) was successfully used to develop Mn2O3–TiO2 (MT) composite thin films by aerosol assisted chemical vapour deposition (AACVD). The Mn2O3–TiO2 composite thin films developed at four different temperatures of 400, 450, 500 and 550 °C were characterized by X-ray diffraction (XRD) and their elemental composition was affirmed by energy dispersive X-ray spectroscopy (EDX). Further field emission gun-scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM), UV–visible absorption spectrophotometry and photoelectrochemical properties were investigated to compare the properties and efficiency of thin films fabricated at 400, 450, 500 and 550 °C. The FEG-SEM and AFM analyses illustrated that the morphology and surface roughness of the thin films significantly depend on the deposition temperature. Films deposited at 500 °C shows agglomerated spinal column scattered vertically on the FTO-coated glass substrate. The direct optical band gap energies of 2.80, 2.52, 2.75 and 2.90 eV for the films fabricated at 400, 450, 500 and 550 °C respectively were found. Photo-oxidation of water via Mn2O3–TiO2 thin films was carried out under simulated solar irradiation of AM 1.5 G (100 mW/cm2) in 0.5 M Na2SO4 using three-electrode photoelectrochemical cell. The films deposited at 500 °C exhibited a better photocurrent density of ∼1.3 mA cm−2 at 0.7 V as compared to the rest of the films grown at different temperatures.