Comparative study of multifunctional properties of the solid-state synthesized ZnO nanostructures and ZnO-graphite nanocomposites

We report that the zinc nitrate, edible sugar, and graphite, along with the surface modifier PEG-400, were mixed in the mortar, followed by a solid-state chemical reaction route, to obtain ZnO nanostructures and ZnO-graphite nanocomposites. The formation of ZnO and ZnO-graphite and their crystalline phases were confirmed from the XRD analysis. Various spectroscopic analyses, including FT-IR, EDX, UV, PL, and 2-dimensional chromaticity, were evaluated for the ZnO nanostructures and ZnO-graphite nanocomposites, and their spectral properties, such as functional groups, elemental composition percentages, light absorption, photoluminescence peaks, and illuminating colour location results, were compared and presented in detail. The ZnO exhibited agglomerated spherical particles, whereas the ZnO-graphite showed binary morphologies such as aggregated nanosheets and spherical particles. Photodegradation efficiency was relatively higher in ZnO-graphite (96.06 %) than in synthesized ZnO (92.36 %).The ZnO-graphite showed a broad and decreased PL intensity throughout the visible range, and improved charge carrier separation compared to ZnO. The antibacterial activity of ZnO-graphite showed a better zone of inhibition related to the ZnO sample against both gram-positive and gram-negative bacteria. The DPPH assay on ZnO-graphite nanocomposites showed a significant enhancement in the free radical scavenging in a dose-dependent manner compared to ZnO. The antioxidant efficiency of ZnO-graphite closely approached that of vitamin C, especially at higher concentrations. The hemolysis percentage for ZnO and ZnO-graphite showed >2 %, indicating the highly hemocompatible nature of the samples according to the ASTM-F7526 standards. Thus, the findings suggest the material has strong potential for optoelectronic, photocatalytic, and biomedical applications.