A straightforward and simpler use of an age-old technique was utilized for the fabrication of “red-emitting magnesium-nitrogen-embedded carbon dots” (r-Mg-N-CD) from the leaves extract of Bougainvillea plant as a natural source of carbon. This technique is similar to the solvent-based technique, which is used for the extraction of fragrances and essential oils from flowers and leaves. The as-derived leaves extract was further carbonized using a simple domestic microwave to obtain the small-sized red-emitting carbonaceous material as r-Mg-N-CD. The r-Mg-N-CD showed excitation-independent emissions at ∼678 nm with excellent photostability and a high quantum yield value (∼40%). Moreover, the important perspective of the present finding is to use this r-Mg-N-CD as a potential photocatalyst material for the degradation of pollutant dye (methylene blue) under the presence of sunlight. To infer the significant influence of using natural sunlight in the process of dye degradation, a comparative analysis was perfo...

Sunlight-Induced Photocatalytic Degradation of Pollutant Dye by Highly Fluorescent Red-Emitting Mg-N-Embedded Carbon Dots

Herein, a potential approach is described for assessing the ecological importance of the graphitic nanocarbons isolated from dirty, dangerous black pollutant particulate material. A simple experiment of photodegradation and a toxicological test were done using the natural sunlight as a source of energy and the pollutant petrol soot derived water-soluble graphene nanosheets (wsGNS) as photocatalyst to achieve complete degradation of pollutant organic dye as methylene blue (MB). Compared to the artificial source of visible light (60W tungsten bulb), the sunlight-induced photodegradation using wsGNS show ∼1.5 times higher rate of photodegradation. The toxicological test confirmed the nontoxic behavior of wsGNS against the two different types of bacterial strains: Gram-negative and Gram-positive cells, Escherichia coli and Staphylococcus aureus, respectively. Moreover, wsGNS are precisely used for the selective photodegradation of MB without harming the bacterial growth from the pool of MB-bacterial strains. ...

Sunlight-Induced Selective Photocatalytic Degradation of Methylene Blue in Bacterial Culture by Pollutant Soot Derived Nontoxic Graphene Nanosheets

The present finding deals with a simple and low-cost fabrication of surface-passivated, brightly fluorescent zinc-oxide-decorated, red-emitting excitation-independent ultrafluorescent CDs, denoted as “CZnO-Dots”. Surface doping of zinc oxide significantly improved the quantum yield by up to ∼72%, and these brightly fluorescent red-emitting CZnO-Dots have been employed for the aqueous-phase photoreduction of 100 ppm hexavalent chromium(VI) to trivalent chromium(III) under the influence of sunlight irradiation. The overall utility of the prepared CZnO-Dots can be ascertained by their recyclability over seven cycles.

Brightly Fluorescent Zinc-Doped Red-Emitting Carbon Dots for the Sunlight-Induced Photoreduction of Cr(VI) to Cr(III)

The findings presented here offer a new approach for the environmental application of pollutant soot somewhat like utilizing a pollutant material for degrading the other pollutant material. Herein, a simpler approach is described for the isolation of two-dimensional graphitic materials as water-soluble graphene nanosheets (wsGNS) from the globally identified dirty–dangerous black pollutant particulate matter as black carbon (BC) from the petrol soot. The as-isolated wsGNS are further employed for the photocatalytic degradation of toxic dye such as methylene blue (MB) under the influence of visible light irradiation. The photodegradation performance of wsGNS compared to insoluble graphene nanosheets (GNS) showed ∼11 times faster degradation rate within ∼90 min of visible light exposure (60 W tungsten bulb). The insights of the aqueous phase photodegradation of MB by the system of MB-wsGNS were studied by different chemical characterization techniques including nuclear magnetic resonance spectroscopy, high-...

Pollutant Soot for Pollutant Dye Degradation: Soluble Graphene Nanosheets for Visible Light Induced Photodegradation of Methylene Blue

A three-dimensional hemin-functionalized graphene hydrogel (Hem/GH) was prepared by a facile self-assembly approach. The as-prepared Hem/GH showed good mechanical strength with a storage modulus of 609–642 kPa and a high adsorption capacity to organic dye contaminants (341 mg g–1 for rhodamine B). Moreover, Hem/GH could be used as a photosensitizer for the photocatalytic degradation of organic dyes and displayed superior photodegradation activity of methylene blue (MB). This result was better than that of counterparts such as graphene hydrogel (GH) and commercial catalyst P25. The excellent cycling performance of the Hem/GH was well maintained even after multiple cycles on adsorption process and photocatalytic reaction. Interestingly, after the photodegradation of MB, a light-induced pH change of the solution from alkaline pH 8.99 to acidic pH 3.82 was observed, and 10 wt % total organic carbon remained. The liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) analysis confirmed the generati...

Construction of Three-Dimensional Hemin-Functionalized Graphene Hydrogel with High Mechanical Stability and Adsorption Capacity for Enhancing Photodegradation of Methylene Blue.

The photocatalytic degradation of methylene blue (MB) under visible light in the presence of a multi-layered graphene quantum dots (MLGQDs) photocatalyst has been investigated in aqueous heterogeneous solution. The photodegradation mechanism, following pseudo first order kinetics, was examined for the effects of the existing monomer (MB+)–dimer {(MB+)2} equilibrium in MB solution. The photocatalytic degradation efficiency of MB+ achieved 93.3% with a rate constant (k) of 0.056 min−1 after 60 min irradiation with green light, while less degradation ∼ 89.44% with k ∼ 0.024 min−1, was achieved for (MB+)2. MB+ is perhaps a short-lived species and favors the photodegradation of MB in comparison to the (MB+)2 species. Similar trends have been found under blue light irradiation. MB+ species easily pulls a proton from the functional groups of MLGQDs, resulting in an intermediate product Luco-methylene blue (LMB). Finally, all MB species and intermediate products degrade into an environmental benign product via highly reactive OH radicals. In addition, our ab initio theoretical results reveals that monomers abstract a proton from hydroxyl groups of MLGQDs and formation of LMB takes place, which is weakly bonded with MLGQDs by hydrogen bonds.

Ranjna Sinha

Papers

Multi-layered graphene quantum dots derived photodegradation mechanism of methylene blue