Near-complete phase transfer of single-wall carbon nanotubes by covalent functionalization

We describe here an efficient phase transfer of single wall carbon nanotubes (SWNTs) from aqueous to non-aqueous media using a unique amide functionalization route, where water soluble SWNTs (2·6 mg/mL) are effectively transferred to solvents like chloroform, toluene and CS2. A maximum of 30 wt% of oxygenated groups have been generated on the side walls by rapid microwave treatment, leading to a solubility of more than 2·6 mg/mL in water. Approximate surface amine coverage of 50% has been accomplished after oxalyl chloride treatment as inferred from thermogravimetry and X-ray photoelectron spectroscopy by controlling several key parameters associated with the extent of functionalization including purity of the sample, temperature and time

RIFAMPICIN: ANTI TUBERCULAR DRUG: AN OVERVIEW

The World Health Organization inspires the use of fixed dose combination (FDC) of rifampicin combination used with isoniazid, isoniazid with pyrazinamide or pyrazinamide with ethambutol for the treatment of tuberculosis. Hence, it’s used worldwide for reducing the risk of emerging drug resistance. Rifampicin is one of the potent and broad spectrum antibiotics against bacterial pathogen. It works by inhibits the DNA dependent RNA polymerase activity by forming stable complex with enzyme. Here, the polymorphic form of rifampicin is describe by thermal study of rifampicin. The thermal behavior of two polymorphic forms of rifampicin was studied by DSC, FTIR, TGA, PXRD. The thermoanalytical results clearly showed the differences between the two crystalline forms. Polymorph I was the most thermally stable form and polymorph II was meta stable. On the DSC study of rifampicin it was shows the difference between both form on basis of melting point and exothermic and endothermic peak. The DSC curve of form I RMP shows the exothermic peak at the temperature between 240- 420ºc and form II RMP shows the endothermic peak at temperature range between 183-188ºc. By using the FTIR spectrum of form I RMP, it was shown that the absorption bands at approximately 3400 cm−1, 1722 cm−1, 1643 cm−1, for the OH of the chain loop group, acetyl group, furanone group sufficient to characterize form I of RMP and form II of RMP, it was shown that the absorption bands at 3356 cm−1 ,1732 cm−1, 1714 cm−1 , for the OH group, furanone group and acetyl group are sufficient to differentiate form I and form II rifampicin. In TGA analysis of RMP both polymorphs shows TGA curve form I occurred at the temperature 224.17 ºC and form II showed the temperature at 194.04 ºC. Powder X-ray diffraction was used to test the polymorphic forms of solid-state rifampicin. Keywords: Rifampicin, thermal study, analytical study, multidrug resistance study, consequences

Interface engineering of SRu-mC(3)N(4) heterostructures for enhanced electrochemical hydrazine oxidation reactions

Hydrazine oxidation in single-atom catalysts (SACs) could exploit the efficiency of metal atom utilization, which is a substitution for noble metal-based electrolysers that results in reduced overall cost. A well-established ruthenium single atom over mesoporous carbon nitride (SRu-mC(3)N(4)) catalyst is explored for the electro-oxidation of hydrazine as one of the model reactions for direct fuel cell reactions. The electrochemical activity observed with linear sweep voltammetry (LSV) confirmed that SRu-mC(3)N(4) shows an ultra-low onset potential of 0.88 V vs. RHE, and with a current density of 10 mA/cm(2) the observed potential was 1.19 V vs. RHE, compared with mesoporous carbon nitride (mC(3)N(4)) (1.77 V vs. RHE). Electrochemical impedance spectroscopy (EIS) and chronoamperometry (i-t) studies on SRu-mC(3)N(4) show a smaller charge-transfer resistance (R-Ct) of 2950 omega and long-term potential, as well as current stability of 50 h and 20 mA/cm(2), respectively. Herein, an efficient and enhanced activity toward HzOR was demonstrated on SRu-mC(3)N(4) from its synergistic platform over highly porous C3N4, possessing large and independent active sites, and improving the subsequent large-scale reaction.Web of Science1212art. no. 156

Tunable optical features from self-organized rhodium nanostructures

Manipulating the surface to tune plasmonic emission is an exciting fundamental challenge and here we report on the development of unique morphology-dependant optical features of Rh nanostructures prepared by an equilibrium procedure. The emergence of surface plasmon peaks at 375 nm and 474 nm, respectively, is ascribed to truncated and smooth surface of nanospheres in contrast to the absence of surface plasmon for bulk Rh(0) in the visible range. Smaller sized, high surface area domains with well developed, faceted organization are responsible for the promising characteristics of these Rh nanospheres which might be especially useful for potential catalytic, field emission and magnetic applications

Preparation and characterization of Rhodium nanostructures through the evolution of microgalvanic cells and their enhanced electrocatalytic activity for formaldehyde Oxidation

Shape-controlled morphological evolution of nanostructured Rh has been demonstrated with the help of a galvanic displacement reaction using Al in 1 mM aqueous Rh(III) chloride at an open circuit potential 0.99 V and at a temperature of 273 κ (room temperature). Nanospheres composed of small nanoparticles of size around 2.9 ± 0.4 nm having uniform distribution with a FCC pattern have been evolved during the course of the reaction. Electrochemical results coupled with structural and morphological characterization data from transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and cyclic voltammetry (CV) suggested the formation of Rh nanostructures. Considering the role of the potential of substrate Al and Rh and diffusion of reactant and product species toward and from the surface of the Al, we proposed the tentative mechanism for the formation of microgalvanic cell. Significantly, these rhodium nanostructures exhibit enhanced electrocatalytic activity toward many fuel cell reactions as demonstrated by formaldehyde oxidation in 0.5 M NaOH. The present strategy is expected to be valid for preparing many other similar electrocatalysts (Pt, Au, and Pd) capable of exhibiting such a remarkable size- and shape-dependent reactivity

Enhanced electrocatalytic performance of interconnected Rh nano-chains towards formic acid oxidation

A chain-like assembly of rhodium nanoparticles (5-7 nm mean diameter) has been synthesized from rhodium chloride with the help of polydentate molecules like tartaric and ascorbic acids (1 : 3 in mM scale) as capping agents at room temperature. Subsequent characterization using transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy reveals a unique inter-connected network like features, while their electrochemical behavior using cyclic voltammetry and current-time transient suggests potential applications as electrocatalysts in fuel cells. A significant negative shift in the onset potential as well as higher anodic peak current density for formic acid oxidation on Rh-tartaric acid (Rh-TA) as compared to that of bulk Rh metal confirms their higher electrocatalytic activity. Interestingly, the enhancement factor (R) with respect to that of bulk metallic Rh towards formic acid oxidation ranges up to 2000% for Rh-TA and 1200% for Rh-AA (Rh-ascorbic acid) respectively. The composition of Rh nano-chains has been further analyzed with thermogravimetry and Fourier transform infra-red spectroscopy to demonstrate the importance of controlling the chain topology using polyfunctional organic molecules. These findings open up new possibilities for tailoring nanostructured electrodes with potential benefits since the development of a better electrocatalysts for many fuel cell reactions continues to be an important challenge

New Insight into N,S-Doped Carbon Nanosheets Embedded with Ni/NiO Nanocluster Electrocatalysts Derived from Conjugated Polymers for the Oxidation of 2‑Propanol to Acetone

Propanol electrooxidation represents a vital reaction, as it offers a pathway for directly transforming renewable resources into valuable chemical products and green hydrogen. This study presents an approach for the synthesis and characterization of Ni/NiO-NS@CN nanosheets using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronoamperometry (i–t), field emission scanning electron microscopy (FE-SEM), high-resolution transmission microscopy (HR-TEM), UV–vis spectroscopy, Fourier transform infrared (FTIR), X-ray photoelectron (XP) and Raman spectroscopy, X-ray diffraction (XRD), energy-dispersive analysis of X-ray (EDAX), BET (Braunner–Emmet–Teller) surface area measurements, and thermogravimetric analysis (TGA) were employed to provide in-depth characterization of the nanocomposite. The analysis revealed a unique nanosheet template decorated with Ni/NiO, C, N, O, and S elemental composition, exhibiting an irregular distribution with a face-centered cubic (FCC) crystal structure and interlayer d-spacing of ∼0.23 nm. Moreover, the defect-induced carbon backbone featured Ni in the +2 oxidation state. Remarkably, the Ni/NiO-NS@CN nanocomposite demonstrated exceptional electrocatalytic activity and stability for 15,000 s at 0.45 V vs SCE (saturated calomel electrode) in the electrooxidation of isopropanol (iPrOH). It exhibited a significantly lower onset potential (0.32 V vs SCE) and superior performance as compared to oxygen evolution reaction (OER), as well as electrooxidation reactions of ethanol and methanol. Furthermore, this study employed 13C NMR spectroscopy to identify acetone as the primary product of the iPrOH oxidation reaction (iPrOR). Impressively, after 10 h of reaction time, high selectivity and 73% Faradaic efficiency were achieved. This research underscores the critical role of catalyst structure and applied potential in influencing the electrooxidation of iPrOH providing valuable insights under various conditions and opening promising avenues for future green energy and chemical synthesis developments