Photocatalytic and Antibacterial Potential of Chitosan Supported Nickel Oxide/Zinc Oxide Composite Synthesized by Alcohothermal Method

Chitosan-based composites with considerable interest have great significance in photocatalytic and antibacterial applications. Chitosan itself is a special accepted adsorbent for the removal of organic pollutants due to presence of energetic amino and hydroxyl groups. The positive charge of amino group interacts electrostatically with surface of shell membrane to block enzyme actions. In this regard, we have synthesized chitosan supported nickel oxide/zinc oxide composite (Chitosan-NiO/ZnO) via alcohothermal process. The X-ray diffraction pattern confirmed the NiO/ZnO composite which contained cubical NiO and hexagonal ZnO structure. FTIR spectrum demonstrated the presence of vibrational mode of Zn-O and Ni-O in the composite. The UV-vis spectroscopy showed the reduction in optical band gap of Chitosan-NiO/ZnO composite from 2.70 to 2.32 eV as compared to NiO/ZnO. Moreover, Chitosan-NiO/ZnO composite showed 91.8% degradation of methyl blue (MB) dye in 70 min whereas NiO/ZnO showed 90.8% in 100 min. This improvement in photocatalytic behavior is mainly credited to porous structure of Chitosan-NiO/ZnO which helped to provide large surface area and more active sites. Furthermore, addition of chitosan also provided solid support on the surface of composite to enhance the electron/hole pairs recombination. The Chitosan-NiO/ZnO composite also showed high recyclability in the photocatalytic efficiency with loss of only 3% after five runs. Moreover, Chitosan-NiO/ZnO also showed improved antibacterial activity against Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. aureus), which is relatively higher than that of NiO/ZnO composite.