Fenton-mediated thermocatalytic conversion of CO2 to acetic acid by industrial waste-derived magnetite nanoparticles.

Iron oxide dust, discarded as industrial waste, has been used here to fabricate magnetic iron oxide nanoparticles (Fe3O4-NPs). We have proposed the thermo-catalytic reduction of carbon dioxide (CO2) using Fe3O4-NPs in the presence of H2O2 to get acetic acid (AcOH) at near ambient conditions (100 °C, 10 bar) with a maximum yield of ∼0.4 M in a batch-reactor. The importance of H2O2 can be described as it facilitates the production of higher concentrations of OH˙ and H+/˙, which consequently supports the synthesis of AcOH.

3D Porous MoS2-Decorated Reduced Graphene Oxide Aerogel as a Heterogeneous Catalyst for Reductive Transformation Reactions.

The MoS2-based reduced graphene oxide aerogel (MoS2-rGOA)-assisted organic transformation reactions are presented. MoS2-rGOA is used as a heterogeneous catalyst for the reduction of benzene derivatives such as benzaldehyde, nitrobenzene, and benzonitrile to benzyl alcohol, aniline, and benzamide and their derivatives, respectively, in green solvents (water/methanol) and green reducing agents (hydrazine hydrate having N2 and H2 as byproducts). The mechanistic features of the reduction pathway, substrate scope, and the best suitable conditions by varying the temperature, solvent, reducing agent, catalyst loading, time, etc. are optimized. All of the synthesized products are obtained in quantitative yield with purity and well characterized based on nuclear magnetic resonance analysis. Further, it is also observed that our catalyst is efficiently recyclable and works well checked up to 5 cycles.

Non-aqueous onion like nano-carbons from waste diesel-soot used as FRET-based sensor for sensing of nitro-phenols.

Herein, a simple-functionalization method is described to prepare the oleylamine functionalized non-aqueous version of onion-like nanocarbons (ONC-OA), where ONC was isolated from the waste pollutant soot exhausted from the diesel engine. The surface group analysis of ONC-OA has been investigated via Nuclear Magnetic Resonance and X-ray Photoelectron Spectroscopy. ONC-OA shows blue fluorescence with a quantum yield of ∼6% in tetrahydrofuran (THF). The fluorescence-based sensing applications of ONC-OA has been investigated for selective sensing of toxic aromatic nitro-phenols compounds (para-nitro, dinitro, and trinitro phenols) from the tested many nitro organic compounds. Based on the limit of detection values, ONC-OA shows much better results for tri-nitro phenol compared to di and mono nitrophenol. To understand the quenching mechanism, a time-resolved photoluminescence analysis of the sensor with and without the addition of quenchers is performed. The effective lowering in fluorescence lifetime of the sensor after the addition of quenchers concludes that the quenching observed is majorly due to the Förster Resonance Energy Transfer (FRET) mechanism. The real-life application of ONC-OA was analyzed by external spiking of N-PhOHs in soil samples.

Sunlight-promoted photodegradation of Congo red by cadmium-sulfide decorated graphene aerogel.

Herein, a simpler-viable methodology for the surface decoration of pear fruit derived graphene aerogel (GA) via cadmium sulfide (CdS) has been presented. GA can be easily synthesized from bio-mass, which provide an economic advantage. Surface decoration via CdS imparts photocatalytic activities in functionalized graphene aerogels (f-GA). CdS-f-GA is being explored here as a photocatalyst for the degradation of a toxic azo dye named Congo red in the presence of sunlight. The rate and mechanism associated with photodegradation were analyzed by performing kinetics and radical trap-based quenching experiments. Nuclear magnetic resonance and fourier transform infrared spectroscopy analyses of the control and photodegraded products were performed to ensure the degradation of the organic framework of Congo red. Additionally, the real-life applicability of CdS-f-GA was also analyzed by degrading the dye in different types of industrial samples (via the method of external spiking), which can advance its practical relevance.

Thiourea-functionalized graphene aerogel for the aqueous phase sensing of toxic Pb(II) metal ions and H2O2.

A simpler approach of functionalization for the fabrication of thiourea-functionalized-Graphene Aerogel (t-GA) is described here. Graphene Aerogel (GA) was synthesized from bio-mass, which on a simpler oxidative treatment get converted to its water-soluble version due to the impregnation of several oxygenous functionalities like carboxylic, hydroxyl, etc. Further, these carboxylated groups have been functionalized with the molecules of thiourea using the long known dicyclohexylcarbodiimide (DCC) as a coupling agent. The as-synthesized t-GA shows bright yellow fluorescence with a quantum yield of ~3% and holds the high-aqueous solubility and photostability. The fluorescence property of t-GA has been used here for the specific and selective sensing of toxic lead (Pb(II)) metal ions from the used many other metal ions via the fluorescence quenching and showed a limit of detection ~7.3 nM. Further, the mechanism for selective sensing was studied in detail and found to be preferable via ligand to metal charge transfer quenching mechanism. The cyclic voltammetry studies supported the selective sensing of Pb(II). Moreover, t-GA has also been studied for the sensing of hydrogen peroxide and as a yellow fluorescent ink.

N, S-codoped Carbon Dots for Nontoxic Cell Imaging and As a Sunlight-Active Photocatalytic Material for the Removal of Chromium.

Nitrogen-sulfur codoped carbon dots (NSCD) were synthesized via a single-step microwave-assisted method having a fluorescence quantum yield of ∼12%. The NSCD has been proven to be nontoxic and utilized as a fluorescent imaging nanoprobe for cancer cells (HeLa cells) under UV and blue light excitation (in vitro environment). In addition to the long-known cell imaging application, these NSCD have been used as a sunlight active photomaterial for the removal of toxic hexavalent chromium as Cr(VI). The experimental results reveal that the sunlight active NSCD shows good potential toward the photocatalytic removal of Cr(VI) ions from the wastewater. For the environment and water purification purpose, three different wastewater samples were tested that are synthetic wastewater (up to 100 ppm), laboratory wastewater, and Cr(VI) ion-spiked industrial wastewater for the photocatalytic removal of Cr(VI). The biocompatible NSCD as a fluorescent imaging probe of cancer cells along with its fruitful utilization in photocatalysis under sunlight (compared to the dark condition) demonstrates the overall sustainability of the presented process.

Pollutant-Soot-Based Nontoxic Water-Soluble Onion-like Nanocarbons for Cell Imaging and Selective Sensing of Toxic Cr(VI).

Presently, the technologies associated with using waste materials for the fabrication of newer useful materials have been greatly advanced. For the same purpose, a possible sustainable approach is described for the utilization of globally available dirty dangerous material, known as black carbon (BC), in the form of particulate diesel soot. From the black diesel particulate matter, onion-like nanocarbons (ONC) have been isolated followed by their surface functionalization to yield their amine-functionalized water-soluble version as ONC-NH2, which exhibits a high quantum yield value of ∼20%. Concerning the synthetic protocol, the potential associated with the presented report reveals that these ONC were used without being explicitly synthesized. These were just isolated from the diesel soot, which on amine functionalization have been converted to an efficient, biocompatible fluorescent probe for the imaging of cancer (HeLa) cells and selective sensing of toxic chromium Cr(VI) in water. The detailed surface functionalization by the amine molecules in ONC-NH2, which make them readily soluble in aqueous media, is investigated using several spectroscopic techniques such as XPS, NMR, and FTIR.