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.

Interplaying Intrinsic and Extrinsic Proton Conductivities in Covalent Organic Frameworks

Abstract: A sulfonic-acid-based covalent organic framework (TpPa-SO3H) has been synthesized that exhibits intrinsic proton conductivity under anhydrous conditions. The sulfonic acid groups are aligned on the two-dimensional (2D) layers at periodic intervals and promote the proton hopping inside the hexagonal one-dimensional channel. The intrinsic proton conductivity of TpPa-SO3H was measured as 1.7 × 10–5 S cm–1 at 120 °C under anhydrous conditions. To enhance the proton conductivity, we have synthesized a hybrid COF TpPa-(SO3H-Py) by a ligand-based solid-solution approach that contains sulfonic acid as the acidic site, as well as pyridine as the basic site, in order to immobilize acidic proton carrier molecules. Impregnation of phytic acid molecules inside the framework increases the anhydrous proton conductivity up to 5 × 10–4 S cm–1 at 120 °C. Such an approach highlights the advantage and first-time use of hybrid COF for interplaying intrinsic to extrinsic proton conductivity.

Interlayer hydrogen-bonded covalent organic frameworks as high-performance supercapacitors

Abstract: Covalent organic frameworks (COFs) have emerged as promising electrode materials in supercapacitors (SCs). However, their insoluble powder-like nature, poor capacitive performance in pristine form, integrated with inferior electrochemical stability is a primary concern for their long-term use in electrochemical devices. Keeping this in perspective, herein we report a redox active and hydrogen bonded COF with ultrahigh stability in conc. H2SO4 (18 M), conc. HCl (12 M) and NaOH (9 M). The as-synthesized COF fabricated as thin sheets were efficiently employed as a free-standing supercapacitor electrode material using 3 M aq. H2SO4 as an electrolyte. Moreover, the pristine COF sheet showcased outstanding areal capacitance 1600 mF cm–2 (gravimetric 169 F g–1) and excellent cyclic stability (>100 000) without compromising its capacitive performance or Coulombic efficiency. Moreover, as a proof-of-concept, a solid-state supercapacitor device was also assembled and subsequently tested.

Sol-gel synthesis of Au/TiO2 thin films for photocatalytic degradation of phenol in sunlight

Abstract: Thin films of Au/TiO2 on glass substrates have been prepared by simple sol–gel dip coating method using a sol of colloidal gold doped titanium peroxide (Au/TiO2 sol). The sol of colloidal gold and titanium peroxide forms a viscous gel after 1–3 h depending on the concentration of both colloidal gold and titania. The sol of particular viscosity range (140–2800 cps) was used to deposit the Au/TiO2 thin films of uniform thickness on various substrates such as glass slides, glass helix and silica rashig rings. Films deposited on glass plates after drying were transparent, uniform in color as well as thickness. Optical characterization by UV–vis spectrophotometer showed a shift in optical absorption wavelength to visible region may be due to the incorporation of gold nanoparticles into titania structure. The optimum concentration of gold loading was found to be 1–2% (by weight) beyond this the gold particles disturb the gel network resulting the formation of gelatinous precipitate. Thin film photo-catalyst prepared was characterized by various techniques such as UV–vis, TG-DTA, XRD, ICP-OES and TEM. The photo-activity of the thin films was tested in sunlight using phenol as model pollutant. The kinetic study showed that the rate of decomposition of phenol using Au/TiO2 photo-catalyst was improved by 2–2.3 times than undoped TiO2.