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

Abstract Newly synthesized trinuclear bimetallic precursor [Mn 2 Ti( μ 3 −O) (TFA) 6 (THF) 3 ] (1) (where TFA = trifluoroacetato and THF = tetrahydrofuran) was successfully used to develop Mn 2 O 3 –TiO 2 (MT) composite thin films by aerosol assisted chemical vapour deposition (AACVD). The Mn 2 O 3 –TiO 2 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 Mn 2 O 3 –TiO 2 thin films was carried out under simulated solar irradiation of AM 1.5 G (100 mW/cm 2 ) in 0.5 M Na 2 SO 4 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.