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• Thiobarbituric acid functionalized pyrene conjugates are phototoxic against MCF-7 cancer cells under 455 nm LED. • Conjugates shows an intense intramolecular charge transfer (ICT) band in the visible region. • Conjugates photo-generates singlet oxygen with moderate singlet oxygen quantum yield. • DCFDA assay shows photo-generation of ROS by the conjugates in MCF-7 cells. Two thiobarbituric acid-functionalized pyrene derivatives (P1 , P2) have been synthesized to explore the photophysical properties and photodynamic activity of dyes of this type. Both compounds exhibit an intense intramolecular charge transfer (ICT) band at ca. 470 nm, which is absent in the spectra of the precursor. P1 and P2 exhibit singlet oxygen generation on irradiation with light with moderate singlet oxygen yields of 0.36 and 0.32, respectively, in DMSO. P1 showed better photodynamic activity against MCF-7 cells with an IC 50 value of 18.3 μM under illumination at 455 nm for 60 min with a Thorlabs M455L3 LED (330 mW.cm−2). [ABSTRACT FROM AUTHOR]

The current importance of energy production from renewable sources stimulated interest in energy storage systems. Recent research has focused on developing vanadium redox flow batteries (VRFB) for large scale energy storage owing to their cost-effectiveness, flexible design, energy efficiency and long cycle life. Nafion the preferred membrane in VRFB systems has an overall cost of more than 11% in these systems. However, due to its drawbacks of high permeability and high cost limit its suitability for commercial use. Many researchers are therefore keen to develop new chemical designs for synthetic membranes, such as perfluorinated, partially fluorinated, hydrocarbon based and organic-inorganic composite membrane. The sol-gel process, which is mainly based on hydrolysis and condensation reaction offers the possibility of homogeneous preparation of membranes, leading to high proton conductivity and reduced vanadium ion permeability, thereby greatly increasing the cell efficiency. This review summarizes recent development in the synthesis and applications of sol-gel based proton exchange membranes for VRFB system, on which many researchers have been working in recent years. We also discuss critical research areas and the future development of cost-effective sol-gel based membranes for attractive energy storage systems. • Various methods of sol-gel synthesized PEM for VRFB is discussed. • Advantages and technical issues of sol-gel based PEM for VRFB is discussed. • Prospective suggestion for the improvement of sol-gel based PEM for VRFB. • Low-cost and higher performance based materials are proposed. • Challenges and future directions of membrane research are examined. [ABSTRACT FROM AUTHOR]

In this work, nitrogen doped carbon dots (NDCDs) and nitrogen doped carbon dots supported palladium nanoparticles composite (n-Pd@NDCDs) were synthesized through hydrothermal carbonization and thermolytic reduction using Morinda citrifolia (M. citrifolia) fruit and palladium chloride as carbon and Pd precursors, respectively. The synthesized materials viz., n-Pd@NDCDs and NDCDs were duly characterized by high resolution transmission electron microscopy (HR-TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The optical properties of NDCDs were studied by ultraviolet visible (UV–Vis), and fluorescence spectroscopy techniques. Further, the electrocatalytic hydrogen evolution reaction (HER) performance of n-Pd@NDCDs was evaluated by linear sweep voltammetry (LSV), Tafel, and electrochemical impedance spectroscopy (EIS) measurements in 0.5 M aqueous H 2 SO 4. The onset potential of n-Pd@NDCDs was about −0.195 V RHE, which was lower than NDCDS (−0.392 V RHE) and bare glassy carbon (−0.603 V RHE). The calculated Tafel slope values of n-Pd@NDCDs were 135 and 141.8 mV/dec, from the voltammetric and EIS methods, respectively. Moreover, the n-Pd@NDCDs exhibited small overpotential of 0.291 V to attain a current density of 10 mA/cm2. The EIS studies revealed that the HER charge transfer resistance was dropped from 84.3 to 18.3 Ω/cm2 while increasing of potential, which revealed good conductivity and electrocatalytic activity of n-Pd@NDCDs. Thus the present work vouched for the candidature of n-Pd@NDCDs as an effective electrocatalyst for the HER in acidic medium. • n-Pd@NDCDs synthesized by reduction of PdCl 2 and carbonization of M.citrifolia. • n-Pd@NDCDs coated GC exhibits good electrocatalytic activity of HER in 0.5 M H 2 SO 4. • The onset potential of n-Pd@NDCDs/GC is about −0.195 V RHE. • Tafel slope of n-Pd@NDCDs (135 mV/dec) is very smaller than NDCDs and bare GC. [ABSTRACT FROM AUTHOR]

Highly fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized using the extract of unripe Prunus mume ( P. mume ) fruit by a simple one step hydrothermal-carbonization method. The N-CDs were synthesized at different pH ranges, 2.3, 5, 7, and 9. The pH of the P. mume extract was adjusted using an aqueous ammonia solution (25%). The optical properties of N-CDs were examined by UV–vis and fluorescence spectroscopy. The N-CDs synthesized at pH 9 emitted high fluorescence intensity compared to other obtained N-CDs. The N-CDs synthesized at pH 9 was further characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform-infra red (FT-IR) spectroscopy. HR-TEM showed that the average size of the synthesized N-CDs was approximately 9 nm and the interlayer distance was 0.21 nm, which was validated by XRD. The graphitic nature of the synthesized N-CDs were confirmed by Raman spectroscopy. XPS and FT-IR spectroscopy confirmed the doping of the nitrogen moiety over the synthesized CDs. The synthesized nitrogen doped CDs (N-CDs) were low toxicity and were used as a staining probe for fluorescence cell imaging. [ABSTRACT FROM AUTHOR]

• Undoped and heteroatoms doped CDs was biogenically synthesized from S. malaccense. • Effect of heteroatoms doping on fluorescence and catalytic ability of the CDs was studied. • Profound catalytic ability of the obtained CDs was utilized through methylene blue reduction. • Highly fluorescent heteroatoms doped CDs were used as bio-imaging probe to detect hela cells. • Catalytic and fluorescent staining ability of heteroatoms doped CDs were compared and reported. The proficient carbon nanocatalysts and incredible fluorescent bio-imaging probes have been successfully fabricated and compared their remarkable efficiencies in this work. The work describes the preparation of undoped and heteroatoms (N, B & S) doped carbon dots from the Syzygium malaccense (S. malaccense) fruit extract via a simple and low cost hydrothermal carbonization method. The obtained pure and heteroatoms doped CDs were characterized and confirmed spectrometrically through various analytical techniques. The size of the obtained CDs, N CDs, B-CDs and S-CDs were found to be 4.68, 4.50, 3.71 and 3.10 nm, respectively. HR-TEM studies explored that the synthesized CDs were spherical in shape and the size of the CDs was reduced during doping of heteroatoms. The photophysical properties of the dissimilar CDs were enlightened through UV–Vis spectroscopy and spectrofluorometer. The quantum yield (QY) was found to be 0.32, 0.41, 0.35 and 0.36 for synthesized CDs, N CDs, B-CDs and S-CDs, respectively. The XRD, Raman and SAED results exposed the amorphous nature of the heteroatoms doped CDs. FT-IR, EDAX and XPS studies helped to confirm the doping of heteroatoms (N, B and S) were doped over the CDs surface. The proficient catalytic ability of the various CDs was revealed and compared towards the methylene blue (MB) reduction using NaBH 4. Among the synthesized CDs, the N CDs showed better catalytic ability and efficiently reduced the MB within 10 min. Furthermore, the fluorescent staining ability of the prepared CDs was examined and compared in the in-vitro multicolour HeLa cell imaging. The N CDs were found to give high intense HeLa cell imaging compared to other synthesized CDs. [Display omitted] [ABSTRACT FROM AUTHOR]