Summary
The abundance of biomass waste and their alteration into carbon‐based electrodes grants practical application of the same. The present work describes all‐round utilization of orange peel waste for the synthesis of graphene quantum dots (GQDs) and carbon‐based electrode fabricated via facile hydrothermal reaction. The supernatant liquid is used for Fe3+ ion sensing and the remnant material is used for synthesis of porous carbon for supercapacitor application. GQDs synthesised via hydrothermal and microwave technique showed dual emission in blue and green wavelength region. Presence of Fe3+ ions quenched the fluorescence of GQDs and the selectivity is studied using other metal ions. Concentration of Fe3+ is varied upto 2.0 mM and the corresponding photoluminescence intensity is observed in the range 85–195 unit, indicating the inverse proportionality relation between these parameters. Carbon obtained has a combination of meso/macro and microporous structure with surface area of 64.002 m2 g−1. Porous OC electrode is employed in three electrode system and is fabricated as coin‐cell which delivered specific capacitance of 290.64 F g−1 and 146.9 F g−1, respectively. The asymmetrical supercapacitor delivered an efficiency of 86% after 10 000 charge‐discharge cycle. The resultant material derived from this work is suitable for both energy and sensing application.
A nanomatrix containing molybdate (MoO3) anchored
on
a zeolitic imidazolate framework (ZIF-8) supporting CoNi metal oxide
framework (MOF) has been prepared. The synthesized nanocomposite possesses
a high surface area of 333.66 m2 g–1,
and it contains a mixture of meso- and macroporous structures. When
implicating the nanostructure as an electrode material, the highest
specific capacitance of 1260 F g–1 is obtained for
the appropriate ratio of the MOF. The superior nanocomposite is deposited
on carbon cloth and further tested as an electrode in a coin-cell-based
(C2N1MZ||NGT) hybrid supercapacitor device, which exhibits a capacitance
of 363 F g–1. The nanocomposite is further used
as a transducer in electrochemical sensing of theophylline (TP). Square-wave
voltammetry suggested that the nanomatrix exhibited creditable electrocatalytic
activity and delivered a stable redox peak for different concentrations
of TP ranging from 1 μM to 5 M. The limit of detection of the
electrochemical sensor is calculated to be 75.4 nM, which suggests
the practicality of the sensor. Therefore, the obtained results indicate
that the prepared nanocomposite is suitable for energy and sensing
applications.
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