3D CoMoO4 nanoflake arrays decorated disposable pencil graphite electrode for selective and sensitive enzyme-less electrochemical glucose sensors

Dip-coated carbon nanotube surface deposits as stable, effective response enhancers in pencil lead electrode voltammetry

Graphitic pencil leads (PLs) are inexpensive writing accessories, readily available in stationery shops. Because the round filaments have high conductivity, they are excellent candidates for sustainable electroanalytical sensor fabrication. Here, we show that dip-coated carbon nanotube (CNT) surface deposits can stably enhance the faradaic redox response of cylindrical pencil lead electrodes (PLEs), with just ten simple sequential immersions of assembled PLEs in an aqueous suspension of CNTs producing significant improvement in their analytical performance. Cyclic (CV) and differential pulse (DPV) voltammetry of ferricyanide with unmodified and CNT-modified PLEs confirmed the reproducibility of the modification procedure and the reliability of the extent of signal amplification, as well as the stability of the response. A series of DPV tests with drugs, an environmental pollutant, an enzyme-substrate redox label and an industrial chemical proved the practical applicability of the proposed CNT-PLEs. Based on their observed properties, PLEs with dip-coated CNT deposits are suggested as cost-effective tools for advanced electroanalysis and as green platforms for enzyme biosensor construction.

Fractal Growth of Quasi Two-Dimensional Copper Dendrites by Template-free Electrodeposition

Fractal dendrites are extensively observed in industry, especially in the electrochemical deposition process. The fractal dendrite electrodeposition behavior of quasi-two-dimensional Cu (Q2D-Cu) metal based on the wire is examined via direct electrodeposition using a thin layer reactor. Here, to explain the fractal growth mechanism, the directional migration and random walking of ions are introduced in the traditional diffusion-limited aggregation model, and fractal patterns consistent with the experimental results are successfully simulated. In addition, the Cu fractal dendrite structure is finely adjusted by varying electrodeposition conditions, demonstrating its great potential for further optimization. The CuO/Q2D-Cu fractal dendrite photothermal device fabricated through in situ assembly of CuO nanowires on Cu fractal dendrite has good photothermal conversion ability. Therefore, metal fractal dendrites, which are considered harmful in the electroplating industry, have application prospects in the photothermal field.

A pencil graphite-based disposable device for electrochemical monitoring of sulfanilamide in honey and water samples

The present paper reports a simple, fast, and inexpensive process of manufacturing a disposable pencil graphite electrode (PGE) from widely available materials, which showed a reproducibility of at least 7.5%. The electrode was compared to the commercial glassy carbon electrode (GCE) and showed superior electroanalytical performance for sulfanilamide (SFA) with approximately 3.9-fold higher current density. Additionally, a displacement of the oxidation peak from approximately 80 mV to more cathodic regions was observed. Therefore, a method based on square wave voltammetry (SWV) was developed for the determination of the antimicrobial SFA in honey and tap water samples using the proposed sensor. The optimized method presented good detectability (LOD = 2.37 μmol L^-1), with excellent precision and accuracy (relative standard deviation < 4.2%) and percent recovery from spiked samples ranging from 92 to 97%. In addition, the sensor did not suffer significant interference from sample matrix components and other commonly evaluated antimicrobials, which demonstrates the potential of these electrodes for implementation in routine analysis and quality control.