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High energy density, fast charge–discharge capability, high flexibility, and sustained cycle life are the key challenges in the application of flexible supercapacitors (SCs) in modern electronics. These primary requirements could be accomplished by engineering a new class of current collectors consisting of hierarchical combinations of various active materials. This study reports the selective integration of hierarchical Ni(OH)2 nanoneedle arrays with NiO–NiCo2O4 nanosheet arrays (Ni(OH)2 NNAs@NiO–NiCo2O4 NSAs) on flexible fabric for high-performance electrodes. The novel core–shell-like hetero-nanoarchitectures not only enhance the electrochemical activity and specific surface area but also, more importantly, provide superhighways for the ultrafast transport of electrons and ions. As a battery-type material, the core–shell-like Ni(OH)2 NNAs@NiO–NiCo2O4 NSAs display a high specific capacity of 326.7 mA h g−1 at 2 A g−1 in aqueous 3 M KOH; this value is 1.89, 1.23 and 1.14 times those of NiO–NiCo2O4, NiO@NiO–NiCo2O4 and Co3O4@NiO–NiCo2O4 electrodes, respectively. Most importantly, a flexible hybrid SC (FHSC, Ni(OH)2 NNAs@NiO–NiCo2O4 NSAs//graphene-ink) demonstrates a superhigh energy density of 97.1 W h kg−1 and a superior long cycling lifespan with 94.7% retention over 5000 cycles. Utilizing these excellent energy storage properties, the fabricated FHSC operated a multifunction electronic display and light up different colored light emitting diodes for real-time applications. [ABSTRACT FROM AUTHOR]

In this study we have synthesised and characterised hollow fluorescent carbon nanoparticle (HFCNs) and solid fluorescent carbon nanoparticle (SFCNs) separately using Syzygium cumini extract via a self-catalysis method in large scale for commercialization without providing any external heat. The characterisation of both HFCNs and SFCNs was performed by employing various techniques like UV-Vis, PL, IR, Raman, XPS, TCSPC, FESEM and TEM. The hollow interior of the HFCNs was corroborated by the TEM images. The average particle size distribution of the HFCNs was ∼20–40 nm and their pore size was ∼10–15 nm while the average particle size distribution range of the SFCNs was ∼12 nm. We have further extended our study by exploring the application of the as-synthesised CNs as excellent bio-imaging agents with appreciable cell viability. In addition, the produced CNs were shown to be excellent when applied as fluorescent ink for security purposes. The CNs were also shown to be excellent nanoprobes for Fe3+ ion detection via a “TURN-OFF” mechanism. Furthermore, we utilized the CNs–Fe3+ nanocomposite as a novel nanoprobe for the detection of NH3 and F− using the promising nano carrier ability of the CNs based on a “TURN-ON” mechanism. [ABSTRACT FROM AUTHOR]

In this study we have synthesised and characterised hollow fluorescent carbon nanoparticle (HFCNs) and solid fluorescent carbon nanoparticle (SFCNs) separately using Syzygium cumini extract via a self-catalysis method in large scale for commercialization without providing any external heat. The characterisation of both HFCNs and SFCNs was performed by employing various techniques like UV-Vis, PL, IR, Raman, XPS, TCSPC, FESEM and TEM. The hollow interior of the HFCNs was corroborated by the TEM images. The average particle size distribution of the HFCNs was ∼20-40 nm and their pore size was ∼10-15 nm while the average particle size distribution range of the SFCNs was ∼12 nm. We have further extended our study by exploring the application of the as-synthesised CNs as excellent bio-imaging agents with appreciable cell viability. In addition, the produced CNs were shown to be excellent when applied as fluorescent ink for security purposes. The CNs were also shown to be excellent nanoprobes for Fe 3+ ion detection via a "TURN-OFF" mechanism. Furthermore, we utilized the CNs-Fe 3+ nanocomposite as a novel nanoprobe for the detection of NH 3 and F - using the promising nano carrier ability of the CNs based on a "TURN-ON" mechanism.