Composite Porous Liquid for Recyclable Sequestration, Storage and In†Situ Catalytic Conversion of Carbon Dioxide at Room Temperature.

Permanent pores combined with fluidity renders flow processability to porous liquids otherwise not seen in porous solids. Although porous liquids have been utilized for sequestration of different gases and their separation, there is still a dearth of studies for deploying in situ chemical reactions to convert adsorbed gases into utility chemicals. Here, we show the design and development of a new type of solvent-less and hybrid (meso-)porous liquid composite, which, as demonstrated for the first time, can be used for in situ carbon mineralization of adsorbed CO2 . The recyclable porous liquid composite comprising polymer-surfactant modified hollow silica nanorods and carbonic anhydrase enzyme not only sequesters (5.5 cm3 g-1 at 273 K and 1 atm) and stores CO2 but is also capable of driving an in situ enzymatic reaction for hydration of CO2 to HCO3 - ion, subsequently converting it to CaCO3 due to reaction with pre-dissolved Ca2+ . Light and electron microscopy combined with X-ray diffraction reveals the nucleation and growth of calcite and aragonite crystals. Moreover, the liquid-like property of the porous composite material can be harnessed by executing the same reaction via diffusion of complimentary Ca2+ and HCO3 - ions through different compartments separated by an interfacial channel. These studies provide a proof of concept of deploying chemical reactions within porous liquids for developing utility chemical from adsorbed molecules.

Facile synthesis of 2D CuO nanoleaves for the catalytic elimination of hazardous and toxic dyes from aqueous phase: a sustainable approach.

This article reports for the first time a facile, green synthesis of 2D CuO nanoleaves (NLs) using the amino acid, namely aspartic acid, and NaOH by a microwave heating method. The amino acid acts as a complexing/capping agent in the synthesis of CuO NLs. This method resulted in the formation of self-assembled 2D CuO NLs with an average length and width of ~300-400 and ~50-82 nm, respectively. The as-synthesized 2D CuO NLs were built up from the primary CuO nanoparticles by oriented attachment growth mechanism. The CuO NLs were characterized by an X-ray diffraction (XRD) method, transmission electron microscopy (TEM), selected-area electron diffraction (SAED) pattern, and Fourier transform infrared spectroscopy (FT-IR). The optical properties were investigated using UV-visible spectroscopy. For the first time, rose bengal and eosin Y dyes were degraded photochemically by solar irradiation using CuO NLs as a photocatalyst. The synthesized CuO NLs act as an efficient photocatalyst in the degradation of rose bengal and eosin Y dye under direct sunlight. The degradation of both the dyes, namely rose bengal and eosin Y, took place within 120 and 45 min, respectively, using CuO NLs as a photocatalyst, whereas commercial CuO, SnO2 quantum dots (QDs), and commercial SnO2 took more than 120 and 45 min for the degradation of rose bengal and eosin Y, respectively. The synthesized CuO NLs showed a superior photocatalytic activity as compared to that of commercial CuO, SnO2 QDs, and commercial SnO2. The reusability of the CuO NLs as a photocatalyst in the degradation of dyes was investigated, and it was evident that the catalytic efficiency decreases to a small extent (5-6 %) after the fifth cycle of operation.

A novel and green process for the production of tin oxide quantum dots and its application as a photocatalyst for the degradation of dyes from aqueous phase.

Green synthesis of SnO2 quantum dots (QDs) was developed by microwave heating method using the amino acids, namely, aspartic and glutamic acid. This method resulted in the formation of spherical SnO2 quantum dots with an average diameter less than the exciton Bohr radius of SnO2. The average diameter of SnO2 quantum dots formed using glutamic acid is ∼1.6 nm and is smaller than that formed using aspartic acid (∼2.6 nm). In the electronic spectra, a clear blue shift in the band gap energy from 4.33 to 4.4 eV is observed with a decrease in particle size (2.6-1.6 nm) due to three dimensional quantum confinement effects. The synthesized SnO2 QDs were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FT-IR). The optical properties were investigated using UV-visible spectroscopy. The synthesized SnO2 QDs act as an efficient photocatalyst in the degradation of Rose Bengal and Eosin Y dye under direct sunlight. For the first time, Rose Bengal dye was degraded using SnO2 QDs as a photocatalyst by solar irradiation.

A novel approach for the synthesis of SnO2 nanoparticles and its application as a catalyst in the reduction and photodegradation of organic compounds.

Tin oxide (SnO2) nanoparticles of sizes ∼4.5, ∼10 and ∼30 nm were successfully synthesized by a simple chemical precipitation method using amino acid, glycine which acts as a complexing agent and surfactant, namely sodium dodecyl sulfate (SDS) as a stabilizing agent, at various calcination temperatures of 200, 400 and 600°C. This method resulted in the formation of spherical SnO2 nanoparticles and the size of the nanoparticles was found to be a factor of calcination temperature. The spherical SnO2 nanoparticles show a tetragonal rutile crystalline structure. A dramatic increase in band gap energy (3.8-4.21 eV) was observed with a decrease in grain size (30-4.5 nm) due to three dimensional quantum confinement effect shown by the synthesized SnO2 nanoparticles. SnO2 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and fourier transformed infrared spectroscopy (FT-IR). The optical properties were investigated using UV-visible spectroscopy. These SnO2 nanoparticles were employed as catalyst for the reduction of p-nitro phenol to p-amino phenol in aqueous medium for the first time. The synthesized SnO2 nanoparticles act as an efficient photocatalyst in the degradation of methyl violet 6B dye under direct sunlight. For the first time, methyl violet 6B dye was degraded by SnO2 nanoparticles under direct sunlight.

Biomimetic synthesis of silver nanoparticles using the fish scales of Labeo rohita and their application as catalysts for the reduction of aromatic nitro compounds.

In this article, a cleaner, greener, cheaper and environment friendly method for the generation of self assembled silver nanoparticles (Ag NPs) applying a simple irradiation technique using the aqueous extract of the fish scales (which is considered as a waste material) of Labeo rohita is described. Gelatin is considered as the major ingredient responsible for the reduction as well as stabilisation of the self assembled Ag NPs. The size and morphology of the individual Ag NPs can be tuned by controlling the various reaction parameters, such as temperature, concentration, and pH. Studies showed that on increasing concentration and pH Ag NPs size decreases, while on increasing temperature, Ag NPs size increases. The present process does not need any external reducing agent, like sodium borohydride or hydrazine or others and gelatin itself can play a dual role: a 'reducing agent' and 'stabilisation agent' for the formation of gelatin-Ag NPs colloidal dispersion. The synthesized Ag NPs were characterised by Ultraviolet-Visible spectroscopy (UV-Vis), Transmission electron microscopy (TEM) and Selected area electron diffraction (SAED) analyses. The synthesized Ag NPs was used to study the catalytic reduction of various aromatic nitro compounds in aqueous and three different micellar media. The hydrophobic and electrostatic interaction between the micelle and the substrate is responsible for the catalytic activity of the nanoparticles in micelle.