Electrochemical sensors are gaining significant demand for real-time monitoring of health-related parameters such as temperature, heart rate, and blood glucose level. A fiber-like microelectrode composed of copper oxide-modified carbon nanotubes (CuO@CNTFs) has been developed as a flexible and wearable glucose sensor with remarkable catalytic activity. The unidimensional structure of CNT fibers displayed efficient conductivity with enhanced mechanical strength, which makes these fibers far superior as compared to other fibrous-like materials. Copper oxide (CuO) nanoparticles were deposited over the surface of CNT fibers by a binder-free facile electrodeposition approach followed by thermal treatment that enhanced the performance of non-enzymatic glucose sensors. Scanning electron microscopy and energy-dispersive X-ray analysis confirmed the successful deposition of CuO nanoparticles over the fiber surface. Amperometric and voltammetric studies of fiber-based microelectrodes (CuO@CNTFs) toward glucose sensing showed an excellent sensitivity of ∼3000 μA/mM cm², a low detection limit of 1.4 μM, and a wide linear range of up to 13 mM. The superior performance of the microelectrode is attributed to the synergistic effect of the electrocatalytic activity of CuO nanoparticles and the excellent conductivity of CNT fibers. A lower charge transfer resistance value obtained via electrochemical impedance spectroscopy (EIS) also demonstrated the superior electrode performance. This work demonstrates a facile approach for developing CNT fiber-based microelectrodes as a promising solution for flexible and disposable non-enzymatic glucose sensors.

A series of Cd- and Er-doped bismuth ferrites were synthesized using a simple microemulsion technique. The influence of Cd and Er doping on the structural, ferroelectric, photocatalytic, and dielectric properties of bismuth ferrite (BFO) was examined in this research. The prepared materials were examined by X-ray diffraction, Raman, scanning electron microscopy, and UV-vis techniques. The XRD patterns reflected the formation of a monophasic rhombohedral structure with the space group R3^-c and an average crystallite size calculated to be in the range of 29 to 32 nm. The saturation polarization (P_s), coercivity (H_c), and retentivity (P_r) of the materials were investigated by a hysteresis loop (P-E), and it was perceived that increasing the dopant contents improved the P_s and P_r values, which may be due to the variation of metal cation valence states. In accordance with the photoluminescence (PL) spectra, a highly substituted material displayed lower recombination and increased charge separation rate (e^--h⁺), which eventually contributed to a higher photocatalytic degradation performance of the prepared NMs. Furthermore, as the frequency and dopant concentration increased, the dielectric loss decreased, which could be due to different types of polarization. Bi_1 - xCd_xFe_1 - yEr_yO₃ showed well-saturated hysteresis loops (P-E) with enhanced saturation polarization near 9.7 × 10^-4 μC·cm^-2. The remnant polarization of the BFO and BFOCE NPs was 2.26 × 10^-4 and 8.11 × 10^-4 μC·cm^-2, respectively, under a maximum electric field, which may be due to the variation of the metal cation valence states. The improved ferroelectric and dielectric properties of Bi_1 - xCd_xFe_1 - yEr_yO₃ NPs are attributed to the reduced concentration of defects, the different domain behavior, and the valence state of Cd and Er ions. The electrochemical (crystal violet (CV) and I-V) properties of Bi_1 - xCd_xFe_1 - yEr_yO₃ were all influenced by the dopant concentrations (Cd and Er). The synergistic effects of Cd and Er on the substituted material enhanced the specific capacitance in comparison to undoped BiFeO₃. The photocatalytic activity to degrade CV under visible irradiation increased in BFOCE as the dopant (x,y) concentration increased from 0 to 0.25 by showing 84% dye degradation in comparison to pristine BiFeO₃ (53% only) within 120 min under visible light. Moreover, the stability of these prepared nanoparticles was confirmed using recycling experiments, with the results indicating that the synthesized nanomaterials demonstrated promising stability and reusability.

A fiber-shaped self-powering device that can simultaneously realize photoelectric conversion and lithium ion storage is developed with high performance.