查看更多>>摘要：The direct on-site detection of illegal additives in unprocessed food samples is usually a great challenge for electrochemical sensors because of electrode biofouling. In this work, a simple filtration method for the scalable fabrication of disposable single-walled carbon nanotubes (SWCNTs)-based antifouling electrochemical sensors is reported. This method employs flash foam stamp-assisted polydimethylsiloxane (PDMS) patterns to control the region-selective deposition of SWCNTs on polyvinylidene fluoride (PVDF) membranes during filtration, which enables the scalable fabrication of a SWCNTs three-electrode-based sensor with high conductivity, good reproducibility and excellent flexibility. The resulting SWCNTs sensor exhibits a sensitive response towards morphine with a calibration range of 0.2 similar to 100 mu g mL(-1) and a detection limit of 0.06 mu g mL(-1) (S/N = 3). Moreover, probably owing to its unique nanoporous structure, this SWCNTs sensor possesses apparently improved antifouling ability as compared with the widely used glassy carbon electrode (GCE), and allows the direct detection of morphine in unprocessed complex foods such as milk and coffee. The present work thus establishes a simple approach to the scalable production of self-designed SWCNTs electrode arrays suitable for on-site food analysis, which may also provide an alternative to commercial screen-printed carbon electrodes (SPCEs) for electrochemical sensing applications.
查看更多>>摘要：Rational modification of catalysts at electrode surface is essential and vital to regulate the electrochemically catalytic capability. In this work, we established an electrochemical interface functionalized by NiPd nanoparticles (NiPd NPs) mediated by metal-organic frameworks (MOFs) of Ni3HHTP2 (NiPd@Ni3HHTP2) towards assaying H2O2 in living cells. In contrast to NiPd NPs, NiPd@Ni3HHTP2 exhibited greatly enhanced electrocatalytic activity towards the reduction process of H2O2 with an onset potential of 0.10 V (vs. Ag/AgCl), as well as the current density increased by 23%. Moreover, the cathodic peak current showed a good linear relationship with H2O2 concentration in a wide range of 1.0 mu M to 45.0 mM with a detection limit of 0.8 mu M. The developed electrochemical method demonstrated good selectivity towards various potential interferences in cell system, and good reproducibility with a current deviation of 2.1% for 10 different functionalized electrodes. Eventually, the present electrochemical sensor with high selectivity and good stability was employed to monitor the levels of H2O2 released from living cells under oxidative stress.
查看更多>>摘要：Developing highly efficient, low-cost and stable electrocatalysts for oxygen evolution reaction (OER) is momentous to achieve the conversion and storage of sustainable energy. Herein, the CoFe(OH)x/GO composites with accordion-like CoFe(OH)x nanosheets clusters dispersed on graphene oxide (GO) sheets are prepared via a template-assisted route. It is found that the OER performance of the CoFe(OH)x/GO composites strongly depends on the content of GO and the mole ratio of Co/Fe. The optimized CoFe(OH)x/GO composites exhibit remarkably enhanced OER electrocatalytic activity in 1 M KOH with a low overpotential of 294 mV at 10 mA cm-2 and a small Tafel slope of 63.4 mV dec-1, which are far superior to the corresponding Co(OH)2/GO and bare CoFe(OH)x. The enhanced electrocatalytic activity can be ascribed to the regulated electronic structure surrounding the active metal sites by introducing Fe, the improved conductivity by GO for faster charge transfer, and the accordion-like hierarchical structure with increased accessible active sites. This work demonstrates a comprehensive strategy to improve the electrocatalytic performance of transition metal hydroxide based OER catalysts.
查看更多>>摘要：This work reports the noninvasive electrochemical determination of glucose by strontium doped cobaltic cobalt oxide nanostructures (Sr-Co3O4). The Sr-Co3O4 is prepared by three conventional methods namely hydrothermal, magnetic stirring, and ultrasound. Among all, the hydrothermal method effectively incorporated the Sr in the Co3O4 lattice. The Sr percentage and Co oxidation states were investigated by x-ray photoelectron spectroscopy. The Sr has a more ionic radius than cobalt, therefore, it is occupied in the octahedral site. As a result, the non-stoichiometric oxygen content was increased in the Co3O4 lattices, which are the main contributor to the electrochemical determination of glucose. The results revealed that hydrothermally synthesized Sr-Co3O4 (HSC) exhibited improved electrocatalytic activity such as low peak potential (0.55 V) and high current (116 mu A) towards glucose oxidation than the other electrocatalysts. The HSC/GCE revealed a good sensitivity (9.01 +/- 0.15 mu A mM(-1) cm(-2)) and low LoD (31 +/- 3 nM). Also, high selectivity was observed towards glucose detection in the presence of co-interfering species. Moreover, the Sr-Co3O4 is applied in real-time monitoring of glucose in blood serum and sweat samples which received good recoveries.
查看更多>>摘要：3D printing is a useful and novel approach towards the manufacturing of electrochemical sensors, due to the ability to make electrodes in any geometry. Electrodes made using 3D printers and pens are seldom used as printed. Most commonly, the electrode surface is polished prior to use. We explored the performance of electrochemically pretreated native (where the surface structure of the printed part was not altered) or mechanically polished electrode surfaces made using two different 3D printing manufacturing approaches. Using a 3D printer and pen, electrodes were made using carbon black/polylactic acid (CB/PLA) filament. Post printing, electrodes were used either as printed or following mechanical polishing. Native electrodes made using the printer had a greater response to inner and outer sphere redox probes, enhanced sensitivity, and greater recovery from dopamine fouling than polished printer made electrodes. This trend was completely reserved in pen made electrodes where the performance of polished electrodes was far greater than that of native electrodes. Native electrodes made using the printer were comparable to polished electrodes made using the pen. These results highlight the influence of printing manufacturing approach and electrode preparation to achieve enhanced analytical measurement.
查看更多>>摘要：The high-performance Fe2SiO4 electrode material is prepared for supercapacitor through KHCO3 activating the carbon and simultaneously etching SiO2 derived from rice husks and hydrothermal treatment process. The prepared electrode material has a 3D hierarchical interconnected pore structure, which provides abundant channels and shorter diffusion pathways for electrons and ions. The SiO2 of rice husks is converted into Fe2SiO4 by loading Fe element, which provides the larger specific capacitance. The Si-O-C bond in the cell wall of rice husks can reduce the electron transfer barrier at the heterogeneous interface. The single electrode shows the specific capacitance of 534.345F center dot g-1 at the current density of 0.5 A center dot g-1, surpassing the silicate materials previously studied. The assembled solid-state asymmetric supercapacitor device of FeSi//activated carbon has a large energy density and power density, reaching 0.69 Wh center dot m-2 at 13.50 W center dot m-2. Additionally, the device presents good cycle performance for 8000 cycles with 85% retention. This work provides a new strategy for the green application of rice husks and promotes the development of low-cost electrode materials for supercapacitors.
查看更多>>摘要：The electrochemical nitrogen reduction reaction is a more ecologically friendly alternative to the high-energy Haber-Bosch method for ammonia manufacturing, but was lack of efficient catalyst, especially in the neutral electrolyte. Inspired by the composition of biological nitrogenase with the elements of Mo, Fe and S, vulcanized FeMoO4 was designed as the nitrogen reduction electrocatalyst, which exhibited excellent catalytic performance and stability for nitrogen reduction reaction (NRR) in neutral media. During the NRR test, the vulcanized FeMoO4 achieved 31.93 mu g h(-1) mg(cat.)(-1) ammonia production rate and high Faradaic efficiency (30.9%) at -0.39 V versus the reversible hydrogen electrode (RHE) in 0.1 M Na2SO4. The results demonstrated the viability of Fe-Mo base as an electrocatalyst for NRR and laid the path for the creation of a nitrogenase-like biomimetic electrocatalysts to achieve the effective N-2 fixation.
查看更多>>摘要：Electrochemically controlled synthesis of small molecules, DNA and various nanostructures provided unparalleled advantages to remotely control chemical reactions with high spatial and temporal precision. Although electrochemistry has been reported to actuate the reversible movement of DNA switch or tune the formation of hydrogen bonds in double strand DNA, electrochemically driven formation of DNA nanostructures remains a challenge as the result of their three-dimensional shapes and complex DNA folding pathway. Herein, through integrating a microfabricated chip with three-electrode system, we reported an electrochemical method to control the formation of tetrahedral DNA nanostructures. Using this method, the relation between the potential and solution pH value, and the melting temperature of double strand DNA was built, which facilitates synthesis of the tetrahedron DNA nanostructures in 6 min. Structure characterization of the prepared DNA nanostructures with atomic force microscopy (AFM) proved the physical integrity of the prepared DNA structures. By modifying the prepared DNA structure on the gold electrodes, a DNA nanostructure-based electrochemical biosensor with high sensitivity toward target DNA was fabricated. Based on these advantages, this method holds promise to develop high-throughput electrochemical microdevices capable of in-situ production of DNA nanostructures and the consequent multichannel biosensing.
查看更多>>摘要：In this study, a one-step in situ method was developed for the preparation of mesoporous molecularly imprinted sensor for the determination of indole-3-acetic acid. The as-obtained molecularly imprinted films well maintained the mesoporous structure but numerous microporous formed after removal of indole-3-acetic acid. The molecularly imprinted sensors were characterized by various analytical techniques and the data indicated a substantial increase in the electroactive surface area and electrochemical properties of the as-prepared molecularly imprinted sensor thanks to the micro/nanoporous structure. The sensor also showed much better sensitivity and selectivity toward the electrochemical determination of indole-3-acetic acid when compared to both non-imprinted sensor and bare glassy carbon electrode. Under the optimal experimental conditions, the molecularly imprinted sensor displayed a good linear response toward indole-3-acetic acid from 0.080 to 10 mu M with a detection limit of 0.050 mu M (S/N = 3) and a good selectivity toward common interfering substances. Moreover, the as-prepared molecularly imprinted sensor successfully determined indole-3-acetic acid in real samples composed of soybean sprout and mungbean sprout. In sum, the suggested simple strategy looks promising for the construction of high sensitivity and selectivity electrochemical sensors.
Borzenko, Marina, IZagrebin, Pavel A.Spector, Elizaveta A.Nazmutdinov, Renat R....
7页
查看更多>>摘要：Adsorption of Anderson-type polyoxometalates on mercury is addressed by classical polarography. The outersphere perbromate reduction is considered to probe the barrier properties of polyoxometalate adlayers. A mutual effect of polyanions with Co(II), Co(III), and Ni(II) as central atoms is shown to affect both their adsorption and the inhibition of perbromate reduction, as well as the self-inhibition of Co(III) reduction. The difference in adlayer-induced inhibition effects for individual polyanions and their mixtures is interpreted on the basis of molecular modeling with account for co-adsorption with cations. Our observations demonstrate that a wide variety of barrier properties can be implemented due to orientation effects and adsorption behavior controlled by the electrode charge.
NSTL
Elsevier