Preparation and study of ternary polypyrrole-tin oxide-chitin nanocomposites and their potential applications in visible light photocatalysis and sensors

[Display omitted] •Nanocomposites synthesized by simple chemical oxidative polymerisation technique.•Increasing tin oxide content shows lower recombination rate and higher charge separation effect.•Enhanced degradation of dye solution were also observed using bio-nanocomposites.•pH and recyclability also showed better performance of photocatalyst.•Nanocomposites were effectively used as electrocatalyst in detection of methanol. In the present study, nanoparticles of tin oxide were synthesised by co-precipitation method along with polypyrrole-chitin matrix prepared by chemical oxidative polymerisation technique. The synthesized nanocomposites were characterized by Fourier transform–infra red spectroscopy (FT-IR), UV-diffuse reflectance spectroscopy (UV-DRS), X-ray diffraction (XRD) to determine the functional group, optical properties, crystallite size and geometry respectively. Moreover scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDAX) was used to study surface morphology and elemental composition of the sample. The synthesised nanocomposites shows enhanced photocatalytic activity towards RhB dyes under visible light with increasing tin oxide content. The holes and superoxide free radicals were found to be dominant species in photocatalysis confirmed by quenching experiment. The photocatalyst also shows better adsorption capability and recyclability, also the photodegradation favours the acidic medium. Furthermore, the electrocatalytic properties of the nanocomposites were also investigated by cyclic voltammetry for detection of methanol (0.001 M to 0.5 M) by drawing cyclic voltammogram in the range −1.0 to +1.0 V at scan rate of 10 mV/s. The nanocomposites as electrocatalyst showed better sensitivity even at lower concentration of 0.001 M. From the given data, it is evident that the synthesized nanocomposites can be used as effective photocatalyst as well as electrocatalyst in different areas.