Polycrystalline Ce-TiO$_2$@rGO compound has been successfully synthesized by hydrothermal method. The synthesized compound was characterized by powder X-ray diffraction (XRD), Fourier transform-infrared spectrophotometer,field-emission scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis to confirm its crystallinity, morphology and thermal stability. From XRD results, crystallite size of the Ce-TiO$_2$@rGO compound was found between 9–15.2 nm, and SEM images confirm the needle-like structure of Ce-TiO$_2$ particles distributed over the reduced graphene oxide (rGO) layer. Further, the electrochemical behaviour of the Ce-TiO$_2$@rGO compound was examined by cyclic voltammetry and differential pulse voltammetry (DPV) techniques for the electrochemical detection of para-nitroaniline. The surface of the glassy carbon electrode was modified by the drop-castingtechnique. The scan rate effect showed that the electrode process is diffusion controlled. T he modified glassy carbon electrode (MGCE) exhibited the 0.347 ${\mu}$M limit of detection, satisfactory sensitivity of 49.12 ${\mu}$A ${\mu}$M$^{-1}$ m$^{-2}$ and linearrange between 0.1 and 1.5 ${\mu}$M. DPV interference studies results confirmed the selectivity of MGCE. The developed MGCE electrochemical sensor thus implemented is also advantageous for its good selectivity, stability, cost-effectiveness, portability and reproducibility.

Zeolite nanoparticles are synthesized by hydrothermal method, and zeolite polypyrrole polymer nanocomposite is chemically polymerized. The polymer nanocomposite of zeolite polypyrrole is used as the gas sensing material.The sensor can detect the ammonia of the lowest concentration of 1 ppm with a response and recovery time of less than a minute. The sensor has a sensitivity of 12.34 ppm$^{-1}$. The polymer composite can also degrade the methylene blue dye inthe presence of UV light up to 79.4%. The powder X-ray diffraction of the materials shows the crystalline nature. The scanning electron microscope micrograph of the zeolite shows the regular hexagonal rod structure having an averagelength of 77.64 nm and diameter of 23.52 nm. In the case of the zeolite polypyrrole SEM micrograph, polypyrrole is encapsulating the zeolite, and also shows the polypyrrole spherical balls.