We propose a novel strategy to prepare poly(3,4-ethylenedioxythiophene) (PEDOT) thin films (PEDOT-GQD) doped with graphene quantum dots (GQD) as an electrode active material for an electrochemical biosensor. The PEDOT-GQD was prepared through simultaneous electropolymerization and doping of EDOT using an ionic complex composed of several Li + cations and one multivalent GQD anion (Li-GQD) by potential cycling without any additives. The Li-GQD, acting as a supporting electrolyte and an anionic dopant, leads a conformational change in the PEDOT chains into an expanded-coil structure. This led to the formation of the PEDOT-GQD with expanded-coil polymeric chains which increases not only intramolecular electron transfer among PEDOT chains but also interfacial charge transfer between the aromatic moieties of target molecules and that of PEDOT through π-π interaction. Moreover, PEDOT-GQD revealed a porous structure with interconnected 3D networks, as GQD doped into the PEDOT backbone affects the growth mechanism of PEDOT. Interestingly, applying a potential of more than + 1.2 V in the electropolymerization caused the mixed formation of oxidized PEDOT and overoxidized PEDOT, leading to the high electrocatalytic activity of PEDOT-GQD. The resulting PEDOT-GQD based electrochemical sensor exhibited excellent electrochemical performances in the simultaneous detection of ascorbic acid, dopamine, and uric acid, such as high sensitivity, selectivity, reproducibility, stability, also in real sample analysis.
Here, a facile and cost-effective hydrothermal method was used to synthesize lithium titanate (Li 4 Ti 5 O 12 , (LTO))-multiwalled carbon nanotubes (MWCNTs) nanocomposite for the bifunctional property of sensing and energy storage applications. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to con rm the formation of LTO-MWCNTs nanocomposite.The electrochemical sensing of Dopamine (DA) at LTO-MWCNTs modi ed glassy carbon electrode (GCE) was studied. The modi ed electrode demonstrated remarkable sensitivity, with a detection limit of 1.54 µM of DA. Moreover, the modi ed electrode was used for the selective measurement of DA in presence of 5-hydroxytryptamine (5-HT) and folic acid (FA) without interfering with their respective potentials. The modi ed electrode was used to quantify the DA in commercial DA injection sample with satisfactory recoveries. The modi ed LTO-MWCNTs/GCE electrode showed acceptable reproducibility and excellent stability. In addition, LTO-MWCNTs nanocomposite electrode delivered a high initial discharge capacity of 176 mAh g − 1 at a charge-discharge rate of 1C in a constant-current charge-discharge experiment, which proved its e cacy as a rechargeable battery anode material.
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