Prosopis juliflora hydrothermal synthesis of high fluorescent carbon dots and its antibacterial and bioimaging applications.

Carbon dots have stimulated the curiosity of biomedical researchers due to their unique properties, such as less toxicity and high biocompatibility. The synthesis of carbon dots for biomedical application is a core area in research. In the current research, an eco-friendly hydrothermal technique was employed to synthesize high fluorescent, plant-derived carbon dots from Prosopis juliflora leaves extract (PJ-CDs). The synthesized PJ-CDs were investigated by physicochemical evaluation instruments such as fluorescence spectroscopy, SEM, HR-TEM, EDX, XRD, FTIR, and UV-Vis. The UV-Vis absorption peaks obtained at 270 nm due to carbonyl functional groups shifts of n→π*. In addition, a quantum yield of 7.88 % is achieved. The synthesized PJ-CDs showing the presence of carious functional groups O-H, C-H, C=O, O-H, C-N and the obtained particles in spherical shape with an average size of 8 nm. The fluorescence PJ-CDs showed stability against various environmental factors such as a broad range of ionic strength and pH gradient. The antimicrobial activity of PJ-CDs was tested against a Staphylococcus aureus, and a Escherichia coli. The results suggest that the PJ-CDs could substantially inhibit the growth of Staphylococcus aureus. The findings also indicate that PJ-CDs are effective materials for bio-imaging in Caenorhabditis elegans and they can be also used for pharmaceutical applications.

Polyhedron shaped palladium nanostructures embedded on MoO2/PANI-g-C3N4 as high performance and durable electrocatalyst for oxygen reduction reaction.

A hybrid catalyst support anchoring a noble metal catalyst could be a promising material for building interfacial bonding between metallic nanostructures and polymer functionalized carbon supports to improve the kinetics of oxygen reduction reaction (ORR). This study successfully prepared a polyhedron nanostructured Pd and MoO2-embedded polyaniline-functionalized graphitized carbon nitride (PANI-g-C3N4) surface using a chemical reduction method. The Pd-Mo/PANI-g-C3N4 achieved an ORR activity of 0.27 mA µg-1 and 1.14 mA cm-2 at 0.85 V, which were 4.5 times higher than those of commercial 20% Pt/C catalyst (0.06 mA µg-1 and 0.14 mA cm-2). In addition, the Pd-Mo/PANI-g-C3N4 retained âˆ¼ 77.5% of its initial mass activity after 10,000 cycles, with only 30 mV half-wave potential reduction. Further, the engineered potential active sites in the catalyst material verified the significant improvement in the ORR activity of the catalyst with increased life-time, and theoretical calculations revealed that the synergistic effect of the catalytic components enhanced the ORR kinetics of the active sites.

Vapour-Phase Selective Hydrogenation of γ-Valerolactone to 2-Methyltetrahydrofuran Biofuel over Silica-Supported Copper Catalysts.

2-Methyltetrahydrofuran (MTHF) is a desirable biomass-based platform chemical with excellent potential as an ideal biofuel, green solvent, and raw material for synthesizing downstream chemicals. In this work, a series of copper nanoparticles encapsulated on SiO2 were prepared by the wet impregnation method and evaluated as efficient non-noble metal catalysts for the vapour-phase hydrogenation of γ-valerolactone (GVL) to MTHF in a fixed-bed reactor under mild reaction conditions. The obtained catalyst properties were determined by XRD, FE-SEM, TEM, UV-DRS, TPR, NH3-TPD, N2O decomposition and pore size distribution measurements. Meanwhile, the parameters/variables tuning their catalytic performance (activity, conversion, selectivity and stability) were examined. Various Cu loadings featured on the SiO2 support are essential for tuning the catalytic activity. Among the catalysts tested, a 5 wt% Cu/SiO2 catalyst showed a 97.2% MTHF selectivity with 71.9% GVL conversion, and showed a stability for 33 h time-on-stream, achieved at 260 °C and atmospheric pressure conditions. It was found that a huge dispersion of Cu metal in support, hydrogen activation ability, abundant acidic sites and surface area are all beneficial for improved MTHF selectivity.

Magnesium Hydrogen Phosphate: An Efficient Catalyst for Acrylic Acid Production from Biorenewable Lactic Acid.

A series of Magnesium hydrogen phosphate (MgHP) catalysts with different magnesium to phosphorous (Mg/P) mole ratios at varying calcination temperatures has been synthesised, bearing in mind the effectiveness as well as the stability of MgHP to catalyse acrylic acid (AA) production from biorenewable lactic acid (LA), a synthetic process applicable to biomass conversion. The physicochemical properties of the MgHP catalysts have been thoroughly characterised and the formation of Mg(NH4)PO4, MgHPO4 and Mg2P2O7 with different structural and acidic properties have been reported. The high catalytic performance of MgHP catalysts with high AA yields (100% conversion and 85% selectivity) at high space velocities (WHSVLA = 3.13 h-1) have been achieved at 360 °C. NH3-Temperature programmed desorption (TPD) and pyridine FTIR have shown that the effectiveness of a catalyst is accounted for not primarily by the actual strength of acidic sites, but is due to the presence of Lewis acidic sites compared to Bronsted sites.

Co3O4 nanoparticles supported mesoporous carbon framework interface for glucose biosensing.

The present work reports the preparation of advanced functional nanostructures based on cobalt oxide supported mesoporous carbon framework (Co3O4@MCF) for electrochemical biosensing. Co3O4@MCF was synthesized by simple hythrothermal & pyrolysis method and further characterized by various microscopic and spectroscopic techniques. The transmission electron microscopic (TEM) images show the lattice fringes of crystalline Co3O4 with interlayer spacing of 0.24 nm. The characteristic 311 plane in X-ray diffraction (XRD) studies further confirmed the presence of crystalline Co3O4 on carbon frameworks. Reflection of prominent A1g peak along with D and G band in raman spectra confirmed the successful fabrication of Co3O4@MCF nanocomposite. Prepared Co3O4@MCF manifested great porosity, good biocompatibility and large surface area which allowed effective immobilization of glucose oxidase (GOx) onto its surface using chitosan (Chi) as a binder. Thus, a nanocomposite (Co3O4@MCF-Chi-GOx) modified glassy carbon electrode (GCE) was fabricated for highly selective detection of glucose using amperometry and cyclic voltammetry. The Co3O4@MCF-Chi-GOx/GCE electrode exhibited excellent biosensing performance for glucose monitoring with detection limit of (LOD) of 107.70 µM and reproducibility of 4.7% RSD. Moreover, the biosensor holds great promise for its effective implications in point-of-care diagnostics of small biomolecules.