Mn2O3-4TiO2 semiconducting composite thin films for photo-electrochemical water splitting

Mn2O3-4TiO(2) composite thin films were deposited on fluorine doped tin oxide (FTO) coated glass substrates from a solution of a newly synthesised hexanuclear single source molecular precursor [Mn2Ti4(TFA)(8)(TFIF)(6)(OH)(4)(O)(2)]center dot 0.4THF 1 (where TFA = trifluoroacetato and THF = tetrahydrofuran) by aerosol-assisted chemical vapour deposition (AACVD) technique. The precursor 1 was characterised by melting point, elemental analysis, Fourier transform infra-red (FTIR) spectroscopy, proton nuclear magnetic resonance (H-1 NMR) spectroscopy, thermogravimetry/derivative thermogravimetry (TG/DTG) and single crystal X-ray analysis. The chemical composition and surface morphology of the fabricated thin film which have been determined by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), suggest the formation of impurity-free nanocrystalline mixtures of Mn2O3-4TiO(2) composite with well-defined and evenly distributed particles in the size range of 112-308 nm. The indirect optical band gap energies of 1.20 and 2.81 eV were estimated by UV-Vis spectrophotometry. The current-voltage characterisation proved that the composite Mn2O3-4TiO(2) electrodes exhibit n-type semiconducting behaviour. The maximum photocurrent density of 3431.1A/cm(2) at 0.7 V versus Ag/AgCl/3 M KCl (similar to 1.23 V versus RHE) was obtained for the Mn2O3-4TiO(2) photoelectrode deposited at 450 degrees C for 45 min from 0.006 M solution of 1 in THF. (C) 2014 Elsevier Ltd. All rights reserved.