Bismuth titanate (Bi₄Ti₃O₁₂, BTO) sol–gel spin coated thin film for heavy metal ion detection

In this work, we report the sol–gel spin-coated novel thin film Aurivillius Phase Layered Bismuth titanate (Bi₄Ti₃O₁₂, BTO) thin film coated on FTO glass substrate annealed at 700 °C was prepared and its detection of mercury ion. The structural orientation, surface morphology, chemical composition, vibrational, and optical properties of the prepared thin film were characterized using XRD, SEM, XPS, Raman, UV–Vis, and PL, respectively. From the XRD analysis, the crystal growth is well preferred in (117) plane corresponding to the orthorhombic structure of BTO. SEM images of the prepared thin film exhibited an anisotropic plate-like grained structure. Photoluminescence spectra showed a good optical emission peak at 545 nm. In Raman spectra, the observed phonon modes are well correlated to the orthorhombic phase of BTO thin films. XPS confirmed the oxidation states of Bi₄Ti₃O₁₂ thin film. The electrocatalytic activity of the prepared BTO thin film electrode concerns mercury detection using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) technique. CV analysis disclosed that the prepared thin film electrode is very active in the electrochemical performance of heavy metal (Hg) detection. LSV result reveals that the prepared thin film exhibits enhanced sensitivity and lower detection limit of electrochemical Hg detection. From the electro-oxidation studies, the BTO thin film electrode acts as a favorable candidate for the application of heavy metal detection.