National Chemical Laboratory

About: National Chemical Laboratory is a facility organization based out in Pune, Maharashtra, India. It is known for research contribution in the topics: Catalysis & Nanoparticle. The organization has 8891 authors who have published 14837 publications receiving 387600 citations.

Visible light induced photoreduction of methyl orange by N-doped mesoporous titania

Abstract: N-doped mesoporous titania was synthesized using templating method. Biopolymer chitosan was used as a template and also as a nitrogen source along with ammonium hydroxide. Three different types of N-doped mesoporous titania were synthesized by varying composition of chitosan and titania precursor. These photocatalysts were characterized using XRD, BET-SA, FTIR, UV-DRS, SEM–EDX and XPS analysis. The photocatalytic activity of mesoporous titania was studied by methyl orange (MO) photoreduction reaction. From the experimental results it was observed that the N-doped mesoporous titania (1:2) gives the highest photocatalytic reduction of MO as compared to N-doped mesoporous titania prepared with (1:1) and (1:3) stoichiometry. This could be due to the optimal level of ‘N’ incorporation in the N-doped mesoporous titania (1:2). Photocatalysts reduce the MO dye into derivative of hydrazine. Photoactivity of N-doped mesoporous titania (1:2) is 1.0721 mg of MO reduced per g of TiO 2 vis-a-vis 0.508 mg of MO reduced per g of TiO 2 for Degussa P25 photocatalyst. The effect of various operating parameters like photocatalyst loading, initial concentration and intensity of light also has been studied.

A cerium-based metal–organic framework having inherent oxidase-like activity applicable for colorimetric sensing of biothiols and aerobic oxidation of thiols

Abstract: A cerium-based metal–organic framework (MOF; 1) with a UiO-66 (UiO: University of Oslo) framework topology was synthesized solvothermally by employing 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid as a ligand. The MOF was thoroughly characterized by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction, infrared spectroscopy, and thermogravimetric and N2 sorption analyses. The activated material (1′) retained its structural integrity in water, acetic acid and 1 M HCl solution. XPS investigation reveals the presence of both Ce(III) and Ce(IV) ions in 1. Owing to the presence of mixed-valence cerium ions, 1′ was able to oxidize the chromogenic peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) or 2,2′-azinobis(3-ethylbenzothizoline-6-sulfonic acid) (AzBTS) in the absence of an external oxidizing agent. Thus, it showed inherent oxidase-like catalytic properties. Inspired by the excellent oxidase-mimicking activity of 1′, a protocol was developed for the rapid colorimetric sensing of biothiols in NaAc buffer (0.2 M, pH = 4). The sensing ability of 1′ towards cysteine was also demonstrated in human blood plasma. Furthermore, the redox-active cerium ions enabled 1′ to exhibit excellent heterogeneous catalytic performance in aerobic oxidation catalysis of thiol compounds. The material is reusable (both as a sensor and as a catalyst), low-cost and highly stable, which renders it a promising candidate for the monitoring of biothiols in immunoassays and medical diagnosis as well as for industrial oxidation catalysis.

Temperature-Dependent Raman Spectroscopy of Titanium Trisulfide (TiS3) Nanoribbons and Nanosheets

Abstract: Titanium trisulfide (TiS3) has recently attracted the interest of the 2D community because it presents a direct bandgap of ∼1.0 eV, shows remarkable photoresponse, and has a predicted carrier mobility up to 10000 cm(2) V(-1) s(-1). However, a study of the vibrational properties of TiS3, relevant to understanding the electron-phonon interaction that can be the main mechanism limiting the charge carrier mobility, is still lacking. In this work, we take the first steps to study the vibrational properties of TiS3 through temperature-dependent Raman spectroscopy measurements of TiS3 nanoribbons and nanosheets. Our investigation shows that all the Raman modes linearly soften (red shift) as the temperature increases from 88 to 570 K due to anharmonic vibrations of the lattice, which also includes contributions from the lattice thermal expansion. This softening with the temperature of the TiS3 modes is more pronounced than that observed in other 2D semiconductors, such as MoS2, MoSe2, WSe2, and black phosphorus (BP). This marked temperature dependence of the Raman spectra could be exploited to determine the temperature of TiS3 nanodevices by using Raman spectroscopy as a noninvasive and local thermal probe. Interestingly, the TiS3 nanosheets show a stronger temperature dependence of the Raman modes than the nanoribbons, which we attribute to lower interlayer coupling in the nanosheets.

Cu:Al Nano Catalyst for Selective Hydrogenolysis of Glycerol to 1,2-Propanediol

Abstract: Non-chromium Cu:Al nano catalyst prepared by simultaneous co-precipitation and digestion method without any template or stabilizer, showed three times higher activity than the bulk Cu–Cr catalyst for hydrogenolysis of glycerol in both isopropanol and water solvents, with the selectivity to 1,2-Propanediol (1,2-PDO) as high as 91% at 493 K and H2 pressure of 7 MPa in 5 h. XRD pattern showed the presence of Cu+ species in the activated Cu:Al nano catalyst. Although Cu+ is catalytically inactive in glycerol hydrogenolysis reaction, the presence of Cu+ helps to stabilize the particle size in a narrow range of 7–11 nm by inhibiting the sintering of copper particles under reaction conditions.