Fabrication of a Hierarchical TiO2 Microsphere/Carbon Dots Photocatalyst for Oxygen Evolution and Dye Degradation Under Visible Light.

Anatase hierarchical TiO2 microsphere/carbon dots composite (HTM/CDs) was fabricated by a facile method for active visible light photocatalysis. The phase, morphology, microstructure and optical properties were investigated by X-ray diffraction, scanning electronmicroscopy, transmission electron microscopy and UV-VIS diffuse reflectance spectroscopy respectively. Under visible light illumination, the fabricated HTM/CDs composite was exhibited an enhanced photo catalytic activity compared to that of pure hierarchical TiO2 microspheres (HTM). Such an enhancement in photocatalytic activity can be attributed to an increase in the absorption of visible light. The photocatalytic activity was investigated by the degradation of a model dyemalachite green (MG) and oxygen production through water splitting.We believe that this type of hybrid material could be used as a highly active and stable visible light photocatalyst to remove pollutants as well as energy production with high performance.

Fabrication of nitrogen- and phosphorous-doped carbon dots by the pyrolysis method for iodide and iron(III) sensing.

A facile and novel strategy to synthesize nitrogen- and phosphorous-doped carbon dots (NPCDs) by single step pyrolysis method is described here. Citric acid is used as carbon source and di-ammonium hydrogen phosphate is used as both nitrogen and phosphorous sources, respectively. Through the extensive study on optical properties, morphology and chemical structures of the synthesized NPCDs, it is found that as-synthesized NPCDs exhibited good excitation-dependent luminescence property, spherical morphology and high stability. The obtained NPCDs are stable in aqueous medium and possess a quantum yield of 10.58%. In this work, a new assay method is developed to detect iodide ions using the synthesized NPCDs. Here, the inner filter effect is applied to detect the iodide ion and exhibited a wide linear response concentration range (10-60 µM) with a limit of detection (LOD) of 0.32 µM. Furthermore, the synthesized NPCDs are used for the selective detection of iron(III) (Fe3+ ) ions and cell imaging. Fe3+ ions sensing assay shows a detection range from 0.2 to 30 µM with a LOD of 72 nM. As an efficient photoluminescence sensor, the developed NPCDs have an excellent biocompatibility and low cytotoxicity, allowing Fe3+ ion detection in HeLa cells.

Nanostructured Fe3O4@Fe2O3/Carbon Dots Heterojunction for Efficient Photocatalyst Under Visible Light.

A facile method for the synthesis of porous magnetic nanoparticles (Fe3O4@Fe2O3) embedded with carbon dots (CDs) are demonstrated for photocatalysis study. Here, a simple, low-cost and green method is developed to synthesize CDs from natural source. The synthesized carbon dots are highly water soluble and monodisperse with particle size 2­5 nm. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-Vis absorption spectroscopy, BET surface area were employed to investigate the crystal structure, morphology, surface groups, optical properties, surface area of the synthesized nanocomposites. The photocatalytic performance of the nanocomposites was analyzed for the degradation of methylene blue under visible light and exhibited higher photocatalytic activity compared to Fe2O3 nanoparticles. Here the crucial role of CDs has been illustrated for the enhancement of photocatalytic activity.

Synthesis of highly fluorescent nitrogen and phosphorus doped carbon dots for the detection of Fe(3+) ions in cancer cells.

Highly fluorescent nitrogen and phosphorus-doped carbon dots with a quantum yield 59% have been successfully synthesized from citric acid and di-ammonium hydrogen phosphate by single step hydrothermal method. The synthesized carbon dots have high solubility as well as stability in aqueous medium. The as-obtained carbon dots are well monodispersed with particle sizes 1.5-4 nm. Owing to a good tunable fluorescence property and biocompatibility, the carbon dots were applied for intercellular sensing of Fe(3+) ions as well as cancer cell imaging.