Nitrite ion sensing properties of ZnTiO3–TiO2 composite thin films deposited from a zinc–titanium molecular complex

Abstract

A titanium based heterobimetallic molecular precursor, [Zn₂Ti₄(μ-O)₆(TFA)₈(THF)₆]·THF (1) (where TFA = trifluoroacetato; THF = tetrahydrofuran), has been designed and scrutinised for its various physicochemical properties by melting point analysis, microanalysis, Fourier transform infra-red spectroscopy, proton nuclear magnetic resonance spectroscopy, thermogravimetry and single crystal X-ray structural analysis. ZnTiO₃–TiO₂ composite thin films were grown on a fluorine doped tin oxide (FTO) coated conducting glass substrate at 550 °C from three different solutions of (1) viz. methanol, THF and acetonitrile, by the aerosol-assisted chemical vapour deposition technique. The phase identification, chemical composition and microstructure of the fabricated thin films that were probed by powder X-ray diffraction, Raman spectroscopy, energy dispersive X-ray analysis and scanning electron microscopy revealed the formation of a 1 : 1 ratio of ZnTiO₃ : TiO₂ composite microspheres of diverse designs and textures depending on the type of deposition solvent used. The direct band gap energy of 3.1 eV was estimated by UV-visible spectrophotometry of the ZnTiO₃–TiO₂ film fabricated from methanol solution and the film electrode was further tested as an electrochemical sensor for the detection of nitrite ions.