Hypercrosslinked pyrrole was synthesized via the Friedel-Crafts reaction and then carbonized to obtain urchin-like nitrogen-doped carbon (UNC). Ultrasmall iron oxide nanoparticles were then supported on UNC, and the composite was used to prepare an electrochemical sensor for detecting uric acid (UA) in human urine. Fe_xO_y/UNC was characterized and analyzed via scanning electron microscopy, transmission electron microscopy, energy dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. A glassy carbon electrode (GCE) modified with Fe_xO_y/UNC was used as an electrochemical sensor to effectively identify UA. The electrochemical behavior of the Fe_xO_y/UNC-based UA sensor was studied using differential pulse stripping voltammetry, and the optimal conditions were determined by changing the amount of Fe_xO_y/UNC, pH of the buffer solution, deposition potential, and deposition time. Under optimal conditions, the Fe_xO_y/UNC-based electrochemical sensor detected UA in the range of 2-200 μM, where the limit of detection (LOD) for UA was 0.29 μM. Anti-interference experiments were performed, and the sensor was applied to the actual analysis of human urine samples. Urea, glucose, ascorbic acid, and many cations and anions present at 100-fold concentrations relative to UA did not strongly interfere with the response of the sensor to UA. The Fe_xO_y/UNC electrochemical sensor has high sensitivity and selectivity for uric acid in human urine samples and can be used for actual clinical testing of UA in urine.

In this study, single-walled carbon nanoangles/carbon nanofibers (SWCNHs/CNFs) were synthesized by electrospinning, followed by annealing in a N₂ atmosphere.

A novel Co ₉ S ₈ nanocage was fabricated via a metalorganic frameworks engaged strategy. The morphology and structure of the resulting Co ₉ S ₈ nanocage were carefully confirmed by scanning electron microscopy, powder X-ray diffraction, transmission electron microscope, and X-ray photoelectron spectroscopy. Then the as-synthesized Co ₉ S ₈ nanocage material was immobilized on a glassy carbon electrode (GCE) and served as an efficient sensing platform for determination of luteolin. Under optimized conditions, the prepared Co ₉ S ₈ /GCE shows significant electrocatalytic activity toward the oxidation of luteolin. By comparison with GCE and CoS/GCE, the proposed Co ₉ S ₈ /GCE results in great improvement in the electrochemical response of luteolin. Meanwhile, the Co ₉ S ₈ based-sensor presents an excellent linear relationship with the concentration of luteolin ranging from 0.01 to 20 μ M. Then, the limit of detection based on S/N = 3 was estimated to be 0.8 nM. In addition, the Co ₉ S ₈ /GCE displays good repeatability, reproducibility, and selectivity. Finally, the simplicity and low cost of this sensor makes it possible to determination luteolin in actual sample with good accuracy and precision.

In this paper, bi-functional polyaniline/polyacrylamide (PANI/PAAm)-hydrogel is fabricated. The hydrogel has capacitive performance and can be used for monitoring human motions. The effect of polyaniline doped with two different acids on the properties of hydrogels was researched. The first type of PANI-hydrogel is doped with hydrochloric (HCL) and the second one with p-toluenesulfonic acid (PTSA). One application of these two kinds of hydrogels were prepared to serve as solid electrolytes in supercapacitors with sandwich structure. The sandwich structure was constructed by introducing two PANI-films reinforced parts on both sides of the PANI-hydrogel. Supercapacitors with sandwich structure possess areal capacitance of 635mF/cm² (HCL-PANI-hydrogel) and 1022mF/cm² (PTSA-PANI-hydrogel). In this structure, PANI-hydrogel provide channels for ion transport as a solid electrolyte. In addition, the PANI-hydrogel can be utilized as the sensitive sensors as well. By employing I-v curve and I-t curve to characterize the performance of the sensor, the hydrogel material can be used as a wearable sensor with sensitivity to slight deformation. This is a sensitive sensor that it can respond to the speed and amplitude of the bending movement of the arm. The effective bi-functional property results indicate that the hydrogel, capacitive and conductive PANI-hydrogel, has great piezoelectric sensitivity as the sensors, which has become promising materials for wearable sensors and solid electrolytes.

TiO₂ powder was firstly synthesized and carbon fiber was secondly prepared via the carbonization of polyaniline fiber, and TiO₂/carbon fiber composites were lastly synthesized via a simple method at room temperature. The prepared samples are evidently investigated by X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, photoluminescence spectrum, and X-ray photoelectron spectroscopy, respectively. Using the monochromatic light of ultraviolet, the photocatalytic activity of the TiO₂/CF composites was accurately evaluated with respect to the degradation of an aqueous dye (methylene blue) solution. The relationship between the photocatalytic degradation of methylene blue dye and its ratio, contact time, and the amount of catalyst was studied. The kinetics and mechanisms of degradation were discussed. The results show that TiO₂/CF composites have good photocatalytic activity and stability. The TiO₂/CF2/1 composite was used in effective photocatalytic degradation of methylene blue, the weight ratio of TiO₂ to carbon fiber was 2:1, and the degradation rate was obtaining up to 97.7 of degradation during 120 min of reaction. The photocatalytic stability of TiO₂/CF composites was dependent on the stability of their structure. After 5 repeated uses, the composite TiO₂/CF2/1 still exhibited rather high activity toward the degradation of methylene blue, where the decolorization efficiency of methylene blue achieved 92 and the loss of activity was negligible. Based on radical trapping experiments, the mechanism of TiO₂/CF composites on photocatalytic degradation of methylene blue is proposed, which could explain the enhanced photocatalytic activity of the composites better. Superoxide radicals, photogenerated holes, and photogenerated electrons were the main active substances for methylene blue degradation.