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The present study was reported with synthesize of copper oxide nanoparticles by ethno botanical species. Bio convivial and compatible approaches were made to utilize the renewable source of leaves extract of Achyranthes aspera Linn as efficient capping and stabilizing agent as well. Also, natural A. aspera was functioned as reductant in the formation of CuO NPs. The phytosynthesized CuO nanoparticles were extensively characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, Scanning electron microscopy, Energy dispersive X-ray diffraction, High resolution tunnelling electron microscopy and also comprehensively examined their biological applications like antibacterial and antifungal susceptibility against E. lenta, E. aerogenes and C. albicans strains. An XRD result of prepared CuO nanoparticles reveals the monoclinic crystalline structure and average crystallite size of 11–16 nm. The morphology variations for different concentrations of precursor material were noticed by SEM image. Furthermore, the crystalline planes found in SAED pattern of synthesized CuO NPs were coincide to the analysed XRD spectra. In the present study, a novel green approach was used to synthesize of CuO NPs for the antibacterial activity of poorly characterized and emerging pathogens of E. lenta and E. aerogenes. Further, the physicochemical, morphological and biological properties of CuO NPs are discussed. [ABSTRACT FROM AUTHOR]

The aim of the present work is to investigate the change in thermal conductivity and stability of copper oxide (CuO) water-based nanofluids, which are prepared by a two-step process, with different concentrations of anionic (Sodium dodecyl sulfate SDS) and nonionic dispersants (Polyvinyl pyrrolidone PVP). Further, CuO nanofluids and nanoparticles have been characterized by XRD, EDX, FESEM, TEM, DLS, and UV to examine the particle size, elemental composition, morphology, particle size distribution, and band gap. Besides, thermal conductivity and stability of all the fluid samples have been measured with respect to particle volume fraction. The interpretation of particle stability in different weight percent of dispersants in base fluids in the presence of PVP dispersant results in a better stabilizing agent than SDS at higher particle volume fraction. Finally, evaluating the effect of lower dispersant concentration (0.1–0.5 wt%) and particle size on the thermal conductivity of CuO water-based nanofluids confirmed that the significant enhancement of thermal conductivity is observed at lower dispersant concentration and decreases with increase in particle size. The enhancement of thermal conductivity was found to be 38% and 34% at 0.4 wt% of SDS and PVP dispersants. [ABSTRACT FROM AUTHOR]

Graphical abstract illustrating the applications of functionalized GQDs in the domains of biology, electronics, materials science, sensors, energy, environmental science, catalysis, and in engineering. [Display omitted] • The significance of functionalizing graphene quantum dots, functionalization strategies, and synthesis methods are listed. • The various functional moieties and the choices are categorized along with a detailed discussion. • The applications of various functionalized graphene quantum dots are conferred. • The scope of functionalized graphene quantum dots in the domains of science, engineering, sensors, electronics are discussed. • The chemical tunability of graphene quantum dots has been deliberated to provide a powerful entry point for research. Graphene Quantum Dots (GQDs) is the breakthrough and the most known material for their optoelectronic properties. The richness of electrons promotes the GQDs to the next level in a wide variety of applications. An extensive array of domains includes GQDs for several applications such as agriculture, bio-medical, device fabrication, sensor, energy storage, water desalination, environmental remediation, and many more. The functionalization of GQDs enhances their biocompatibility, which can be a substitute for many traditionally available materials which are toxic and hazardous like metal quantum dots and dyes in myriad fields such as biotechnology, immunology, biochemistry, analytical, and diagnostic departments. The nanoscale morphology of the GQDs can alter the device structure and simplify functionality. Functionalized GQDs offer higher efficiency within a time which aids their potential usage in wearable and portable sensor developments. Though GQDs are functionalized with numerous functional materials, biomolecules (carbohydrates, lipids, nucleic acids, and proteins), heteroatoms (S, N, B, Cl, F, etc.,), metals (Au, Ag, metal oxides (copper oxide, iron oxide, bismuth oxide, etc.,), amino acids (glycine, histidine, cysteine, valine, etc.,), polymers (polyaniline, polypyrene, polypyrrole, poly arginine), drugs (penicillamine, folic acid, dopamine, glucose, ascorbic acid), dyes (rhodamine, methylene blue) and many more, the strategies of functionalization are unspoken and need to explore in detail to choose them for the desired applications. Functionalization strategies could be the major factor in altering the resultant functionalized GQDs and their properties. In this review, we have explored several functionalization strategies of GQDs and elucidated their applications in different domains. The elucidation of the functionalization strategies will enlighten the young researchers in availing the correct functionalization method for the opted functional group elements. This will lead to achieving the resultant material with enhanced and tuned properties for the anticipated applications in prevalent fields. [ABSTRACT FROM AUTHOR]

Abstract: The chitosan-copper oxide (Chi-CuO) biopolymer nanocomposites were synthesized by a simple green chemistry method using ascorbic acid as a reducing and capping agent. The intense peak around 300 nm was observed in the UV-visible spectrum indicating the formation of CuO nanoparticles. The prepared Chi-CuO nanocomposites were characterized using energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), and Fourier transform-infrared spectroscopy (FT-IR). SEM and XRD pattern showed cubic shape for Chi-CuO nanocomposites with average crystalline size of 17 nm, as calculated using Debye-Scherrer’s formula. The FT-IR spectral studies showed the Cu-O bond formation with chitosan to form nanocomposites. Synthesized nanocomposites showed significant anti-microbial activity against Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli and Penicillium notatum, assayed using the agar well diffusion method. It also showed sporicidal activity against B. subtilis and exhibited effective biofilm-inhibitory activity against B. subtilis (69%/100 μg/mL) and P. aeruginosa (63%/100 μg/mL).Graphical abstract: [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of CuO Nps via solution combustion method using novel fuel (Chakkota or Pomelo fruit juice). • CuO nanoparticles shows a reversible capacity of 110 mA h g−1 is after 150 cycles at 0.1C current rate. • CuO nanoparticles exhibited better photocatalytic methylene blue dye degradation under visible light source. CuO nanoparticles (NPs) using Pamelo (Binomial name; Citrus maxima) fruit juice as fuel. XRD pattern confirms the monoclinic structure with C2/c point group. In FT-IR spectra peaks at 532 cm−1 is observed for symmetrical stretching vibrations of Cu-O bonds. The UV-DRS spectrum shows characteristic absorption band at 732 nm with corresponding bandgap of 1.62 eV. TEM images show agglomerated irregular shape of nanoparticles with an average particle size of about ~ 60 nm. BET analysis shows mesoporous nature having surface area of 3.7 nm. CuO NPs was examined as anode material for the Li-ion battery and it shows specific capacity at 110 mAh g−1 even after 150 cycles. CuO NPs showed excellent photocatalytic activity (82% in 150 min) against MB dye under visible light irradiation. [ABSTRACT FROM AUTHOR]