NS-CQDs/TiO2 hybrid nanocomposites incorporated with nutshell derived NS-CQDs as photocatalyst for environmental/biological applications and cytotoxicity effect

Being a class of carbon nanoparticles, carbon quantum dots (CQDs) have been used as a precursor in modification of semiconductor photocatalysts. The efficient utilization of natural resources "biomass" for the synthesis of CQDs which are important for reducing environmental pollution, and also creates a field of application area such as water treatment. In this work, fix-bed pyrolysis reactor was used to synthesis the bright fluorescence NS-CQDs using nutshell (NS) without any chemicals. One-dimensional TiO2 nanorods (TNRs) fabricated via hydrothermal route was decorated with low-cost and eco-friendly (NS-CQDs) by wet impregnation method to produce hybrid NS-CQDs/TNRs nanocomposite. Various characterization techniques such as TGA, XRD, XPS, FE-SEM/EDS, HRTEM, FTIR, fluorescence and UV-vis spectroscopy have been employed to confirm the structural and optical properties. The photocatalytic activity of as-prepared NS-CQDs/TNRs were investigated for methylene blue (MB), hexavalent chromium Cr (VI), Escherichia coli (E. coli) and Aspergillus niger (A. niger) under UV-A. Subsequently, MTT assay was carried out using ARPE-19 (Epithelium) and MCF-7 (Breast Cancer) cell lines as the model system so as to designate whether produced NS-CQDs and hybrid NS-CQDs/TNRs composite was cytotoxic or not. The obtained results suggest that the photocatalytic activity of NS-CQDs/TNRs composites was slightly enhanced as compared to that of TNRs while not only NS-CQDs but also NS-CQDs/TNRs composites show no significant change in terms of cytotoxicity.