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Yarn-shaped supercapacitors (SCs) functionalized with pseudocapacitive materials show promise in wearable electronics. However, their development was hindered by poor electrochemical properties, especially long-term cycling stability, owing to the volumetric change during charging/discharging. Herein, we report a ship-in-a-bottle architecture on carbon nanotube yarn (CNTY) based SCs, in which transition metal hydroxide (TMH) nanoparticles (Ni(OH)2 or Co(OH)2) are confined in conducting nanoporous metal-organic frameworks (MOFs, Ni3(HITP)2) which anchor onto CNTY, involves the synergy of nanoconfinement and hydrogen bonding (H-bonding) network to mutually support each phase toward improved electrochemical performance. The Ni(OH)2@Ni3(HITP)2@CNTY electrode possesses an areal specific capacitance of 496 mF cm-2 at 0.4 mA cm-2 due to the hierarchical structure which led to facilitated charge transport and enhanced ion storage. Moreover, the ternary CNTY-based SCs demonstrate exceptional cycle performance (90.9-92.3% capacitance retention after 10 000 cycles at 5 mA cm-2). Importantly, the nanoconfinement is confirmed by field emission scanning electron microscopy, transmission electron microscopy-energy dispersive spectroscopy, and energy dispersive spectroscopy, and Brunauer-Emmett-Teller and cryogenic-TEM characterization studies. The H-bonding (O/H-N) network between Ni(OH)2 and Ni3(HITP)2 is confirmed by Fourier transform infrared spectroscopy and density functional theory calculations. Both nanoconfinement and the Hbonding network contribute to an ultra-stable Ni(OH)2@Ni3(HITP)2 structure due to its high durability to volumetric change caused by phase separation and structural collapse during charging/discharging. [ABSTRACT FROM AUTHOR]

We describe a method for the differentiation of carboxylate anions on disposable paper supports (common printer paper, filter paper, chromatography paper), based on differential patterns of interactions between carboxylates and a fluorescent sensing system. The sensor was built from commercially available components, namely a polycationic fifth generation amine-terminated poly(amidoamine) dendrimer (PAMAM G5) and a small organic fluorophore (calcein) through non-covalent interactions. The assay’s physical dimensions were chosen to conform to the microwell plate standard so detection could be carried out on widely available plate reader instrumentation. The sensing complex was first deposited in spots on a paper support to prepare the sensor strip; a carboxylate solution was then loaded on each spot. Nuanced changes in fluorescence were associated with carboxylate binding to the PAMAM dendrimer, characteristic of the structure and affinity of each carboxylate. Such signal changes, interpreted through Linear Discriminant Analysis (LDA), contained enough information to recognize and successfully discriminate most anions in the panel. Among the substrates we tested, chromatography paper was the most promising. The relationship between the structure of the carboxylates and the patterns giving rise to their differentiation was also discussed. Finally, the long-term stability (“shelf life”) of the pre-assembled [calcein·dendrimer] sensing system was found to be excellent when deposited on paper support. [ABSTRACT FROM AUTHOR]