Capacitive-coupled non-pinched I–V and type II memristive behavior of carbon-TiO2 nanocomposite films fabricated through aerosol flame synthesis

Titanium dioxide (TiO₂) is a long-established semiconductor material used in several electrical and electronical applications, including random-access memories, biohybrid interfaces, sensors, and neuromorphic computing. Nevertheless, such applications are still at an early development stage, constrained by fundamental gaps in understanding and technological limitations. Functional memristive characteristics of TiO₂ rely extensively on the processes, including synthesis techniques, fabrication, and physicochemical modifications. In this work, nanostructured composite films of Carbon (Soot) and TiO₂ are fabricated through a custom-made aerosol flame synthesis (AFS) reactor using a facile one-step synthesis technique with good control over nanostructure, crystallinity, defect chemistry and carbon component inclusions. Scanning mobility particle sizer (SMPS) was employed to analyze particle size distribution in the flame. Microstructures and composition of the C-TiO₂ film were characterized through Raman spectroscopy, UV–VIS spectrophotometry, atomic force microscopy (AFM), and current-voltage I-V measurements. The presence of carbon and TiO₂ across the film was confirmed by the Raman spectrum and quantified by light absorption. The electrical characterization demonstrated a capacitive-coupled non-zero crossing and type-II hysteresis behavior of the C-TiO₂ nanostructured film. Following carbon compositing, TiO₂ exhibited enhanced optical absorption in the visible spectral region and electrical conductivity. The improvement in the conduction pathways was evidenced by the I-V measurements of the TiO₂ film and the C-TiO₂ film. A phenomenon of disappearance and reappearance of the capacitive-coupled memresistive effect was observed after dark and sunlight exposure, most likely due to the photosensitive nature of TiO₂ in the nanocomposite film. This proof-of-concept study testifies that, due to such properties, C-TiO₂ nanocomposite films produced via AFS can be considered as promising future candidates for applications in the field of next-generation electronic devices.