Recent Advancements in Green Synthesis of Nanoparticles for Improvement of Bioactivities: A Review.

Natural products have widely been used in applications ranging from antibacterial, antiviral, antifungal, and various other medicinal applications. The use of these natural products was recognized way before the establishment of basic chemistry behind the disease and the chemistry of plant metabo-lites. After the establishment of plant chemistry, various new horizons evolved, and the application of natural products breached the orthodox limitations. In one such interdisciplinary area, the use of plant materials in the synthesis of nanoparticles (NPs) has exponentially emerged. This advancement has offered various environment-friendly methods where hazardous chemicals are completely replaced by natural products in the sophisticated and hectic synthesis processes. This review is an attempt to under-stand the mechanism of metal nanoparticles synthesis using plant materials. It includes details on the role of the plant's secondary metabolites in the synthesis of nanoparticles including the mechanism of action. In addition, the use of these nanomaterials has widely been discussed along with the possible mechanism behind their antimicrobial and catalytic action.

Single Step Blending of PEDOT:PSS/SPGO Nanocomposite via Low Temperature Solid Phase Addition of Graphene Oxide for Effective Hole Transport Layer in Organic Solar Cells.

Herein, we report the modification of PEDOT:PSS by in-situ direct addition of graphene oxide powder processed by spray dryer (SPGO) for the enhancement in the performance of organic solar cell. The preparation of PEDOT:PSS/SPGO composite was done by direct incorporation of graphene oxide powder at lower temperature i.e., below 5 °C. Raman spectroscopy of the prepared PEDOT:PSS/SPGO nanocomposites at low temperature suggested that low temperature plays a vital role to improve the ability of these composite as hole transport layer by improving adhesive properties of the composite. Atomic force microscopy (AFM) analysis suggested that the adhesive ability of these composite decreased surface roughness and thus providing smoother path for the hole transportation. After the successful synthesis of PEDOT:PSS/SPGO nanocomposites, ITO/PEDOT:PSS/SPGO/PTB7:PC71BM/Al based organic solar cell was fabricated. The J-V curves under AM 1.5G illumination (100 mW/cm²) of the PTB7:PC71BM based OSCs using PEDOT:PSS/SPGO as a HTL exhibit Voc = 0.67 V, Jsc = 17.3 mA, FF = 41.5%, PCE = 4.82%, and device with PEDOT:PSS as HTL exhibit Voc = 0.68 V, Jsc = 16.0 mA/cm², FF = 38.7% and PCE = 4.04%. The enhance PCE in case of PEDOT:PSS/SPGO based devices depicted that the direct inclusion of graphene oxide in PEDOT:PSS increased the PCE almost 16%, which arises due the high conductivity and stable pi-pi stacking of the spray dryer processed graphene sheets with PEDOT:PSS which ease the charge carrier mobility, thus providing feasible path for charge transportation.

Bulk synthesis of graphene nanosheets from plastic waste: An invincible method of solid waste management for better tomorrow.

Waste plastic management and converting it into value added products is one of the greatest challenges before the scientific community. The present work reports a cost effective, environment friendly and mass production capable method for upcycling of solid plastic waste into value added product (graphene). A two step pyrolysis processes i.e. firstly at 400 °C in presence of nanoclay followed by at 750 °C under nitrogen atmosphere was performed to obtain a black charged residue. Raman spectroscopy was performed on the obtained residue, where the observed D and G bands at 1342 cm-1 and 1594 cm-1, respectively, confirm the synthesis of graphene nano sheets. In addition, a broad 2D band at 2790 cm-1 confirm the presence of few layer graphene nano sheets. The obtained graphene nanosheets were also confirmed through the computational data by Gaussian09, where the peaks at 1379 cm-1 and 1596 cm-1 for D and G band, respectively, make a good agreement with experimental data. TEM, FT-IR and EDX spectroscopy were also performed to confirm the synthesis of graphene nanosheets including the functional group identification and quantitative analysis for elements, respectively.