Photocatalytic and Antibacterial Activities of Alternanthera dentata Mediated Bio-nanocomposite of CuO Nanoparticles and DFT Study on the Selective Capping Behavior of Phytocompounds

In this work, we have applied a green chemistry approach for the synthesis of CuO nanoparticles (NPs) using Copper (II) nitrate trihydrate and the leaf extract of Alternanthera dentata plant (ADLE). The UV-vis, FTIR and Gas Chromatography-Mass Spectrometry (GC-MS) analysis of ADLE revealed the presence of a wide variety of bioactive phytochemical constituents in ADLE. In addition to that, we have used the Density Functional Theory (DFT) in order to investigate the stability of CuO bio-nanocomposites. The study of orbital energies of phytochemicals with their highest norm percentage shows that the charge transfers between Distearyl Thiodipropionate to CuO are more dominant as compared to the other phytochemical constituents. Furthermore, it has the highest molecular weight compared to the other phytocompounds. Therefore, these reveal that Distearyl Thiodipropionate is responsible for the stability of CuO nanostructures. The average crystalline size of the CuO NPs is found to be 7.38 nm with 0.27 nm inter-planer spacing with the (110) plane. The fabricated nanoparticles are then employed for the degradation of Congo Red (CR), Malachite Green (MG) and their mixed dye (MD) in the presence of UV light. We have achieved more than 96% degradation with 30 mgL^-1 of CuO NPs in the case of all dye solutions, which is the best result to date. Furthermore, the nanoparticles showed prominent activity against pathogenic bacteria like Klebsiella pneumoniae (ATCC1705) and Staphylococcus aureus (ATCC6538p) which signifies that the antibacterial activity of the CuO NPs is directly proportional to their concentration.