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Pt nanoparticles were deposited on mesoporous carbon material CMK-3. Glucose oxidase (GOx) was immobilized in the resulting Pt nanoparticles/mesoporous carbon (Pt/CMK-3) matrix, and then the mixture was cast on a glassy carbon electrode (GCE) using gelatin as a binder. The glucose biosensor exhibited excellent current response to glucose after cross-linking with glutaraldehyde. At 0.6V (vs. SCE) the response current was linear to glucose concentration in the range of 0.04-12.2mM. The response time (time for achieving 95% of the maximum current) was 15s and the detection limit (S/N=3) was 1 microM. The Michaelis-Menten constant (K(m)(app)) and the maximum current density (i(max)) were 10.8 mM and 908 microAcm(-2), respectively. The activation energy of the enzymatic reaction was estimated to be 22.54 kJ mol(-1). The biosensor showed good stability. It achieved the maximum response current at about 52 degrees C and retained 95.1% of its initial response current after being stored for 30 days. In addition, some fabrication and operation parameters for the biosensor were optimized in this work. The biosensor was used to monitor the glucose levels of serum samples after being covered with an extra Nafion film to improve its anti-interferent ability and satisfied results were obtained.

The electrochemical behaviors of estrone at various carbonaceous nanomaterials-dihexadecyl hydrogen phosphate (DHP) composite films coated glassy carbon electrodes were investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronocoulometry (CC) and electrochemical impedance spectroscopy (EIS). Comparing with the composite films of acetylene black (AB) and carbon nanofiber (CNF), multi-wall carbon nanotubes (MWCNTs)-DHP film showed the best electrochemical performance towards the oxidation of estrone, reflected by the significantly enhanced oxidation current in the voltammograms as well as the apparently reduced charge transfer resistance in EIS. Studies on the active surface area, the surface coverage and EIS suggested that the apparently improved electrochemical responses of estrone at MWCNTs should arise from their large surface area, good conductivity and the ability to facilitate the charge transfer process. The reaction mechanisms of estrone oxidation at the three composite films were also discussed, which were expected to follow a process involved the total loss of two electrons and two protons.

The direct electrochemistry of glucose oxidase (GOD) entrapped in nano gold particles (NAs)-N,N-dimethylformamide (DMF)-1-butyl-3-methylimidazolium hexafluophosphate (BMIMPF(6)) composite film on a glassy carbon electrode (NAs-DMF-GOD (BMIMPF(6))/GC) has been investigated for first time. The immobilized GOD exhibits a pair of well-defined reversible peaks in 0.050 M pH 5 phosphate solutions (PS), resulting from the redox of flavin adenine dinucleotide (FAD) in GOD. The peak currents are three times as large as those of GOD-NAs-DMF film coated GC electrode (i.e. NAs-DMF-GOD (water)/GC). In addition, the NAs-DMF-GOD (BMIMPF(6)) composite material has higher thermal stability than NAs-DMF-GOD (water). Results show that ionic liquid BMIMPF(6), DMF and NAs are requisite for GOD to exhibit a pair of stable and reversible peaks. Without any of them, the peaks of GOD become small and unstable. Upon the addition of glucose, the peak currents of GOD decrease and a new cathodic peak occurs at -0.8 V (versus SCE), which corresponds to the reduction of hydrogen peroxide (H(2)O(2)) generated by the catalytic oxidation of glucose. The peak current of the new cathodic peak and the glucose concentration show a linear relationship in the ranges of 1.0 x 10(-7) to 1.0 x 10(-6)M and 2.0 x 10(-6) to 2.0 x 10(-5) M. The kinetic parameter I(max) of H(2)O(2) is estimated to be 1.19 x 10(-6)A and the apparent K(m) (Michaelis-Menten constant) for the enzymatic reaction is 3.49 microM. This method has been successfully applied to the determination of glucose in human plasma and beer samples, and the average recoveries are 97.2% and 99%, respectively.

Metallic sulfide anodes show great promise for sodium‐ion batteries due to their high theoretic capacities. However, their practical application is greatly hampered by poor electrochemical performance because of the large volume expansion of the sulfides and the sluggish kinetics of the Na+ ions. Herein, a porous bimetallic sulfide of the SnS/Sb2S3 heterostructure is constructed that is encapsulated in the sulfur and nitrogen codoped carbon matrix (SnS/Sb2S3@SNC) by a facile and scalable method. The porous structure can provide void space to alleviate the volume expansion upon cycling, guaranteeing excellent structural stability. The unique heterostructure and the S, N codoped carbon matrix together facilitate fast‐charge transport to improve reaction kinetics. Benefitting from these merits, the SnS/Sb2S3@SNC electrode exhibits high capacities of 425 mA h g−1 at 200 mA g−1 after 100 cycles, and 302 mA h g−1 at 500 mA g−1 after 400 cycles. Moreover, the SnS/Sb2S3@SNC anode shows an outstanding rate performance with a capacity of over 200 mA h g−1 at a high current density of 5000 mA g−1. This study provides a new strategy and insight into the design of electrode materials with the potential for the practical realization and applications of next‐generation batteries. [ABSTRACT FROM AUTHOR]

Abstract: The direct electrochemistry of hemoglobin (Hb) has been achieved by immobilizing Hb on mesoporous Al2O3 (meso-Al2O3) film modified glassy carbon (GC) electrode. Meso-Al2O3 shows significant promotion to the direct electron-transfer of Hb, thus it exhibits a pair of well defined and quasi-reversible peaks with a formal potential of −0.345V (vs. SCE). The electron-transfer rate constant (k s) is estimated to be 3.17s−1. The immobilized Hb retains its biological activity well and shows high catalytic activity to the reduction of hydrogen peroxide (H2O2) and nitrite (NO2 −). Under the optimized experimental conditions, the catalytic currents are linear to the concentrations of H2O2 and NO2 − in the ranges of 0.195–20.5μM and 0.2–10mM, respectively. The corresponding detection limits are 1.95×10−8 M and 3×10−5 M (S/N=3). The resulting protein electrode has high thermal stability and good reproducibility due to the protection effect of meso-Al2O3. Ultraviolet visible (UV–vis) absorption spectra and reflection–absorption infrared (RAIR) spectra display that Hb keeps almost natural structure in the meso-Al2O3 film. The N2 adsorption–desorption experiments show that the pore size of meso-Al2O3 is about 14.4nm, suiting for the encapsulation of Hb (average size: 5.5nm) well. Therefore, meso-Al2O3 is an alternative matrix for protein immobilization and biosensor preparation. [Copyright &y& Elsevier]

A gold nanoparticles-dihexadecyl hydrogen phosphate (DHP) film on a glassy carbon electrode (GCE) was fabricated. Gold nanoparticles were dispersed into DHP solution to give a homogeneous and stable suspension. A stable and uniform Aunano-DHP film was obtained on the GCE surface using a convenient coating technique. This nanostructured electrode exhibited excellent sensing for the oxidation of glucose. A novel electroanalytical method for the determination of glucose was developed. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Although substantial statements report the capability of graphene for corrosion prevention, its further application is limited by the non-comprehension of its structural variation in different coatings. Herein, graphene sheets with four structures were incorporated waterborne epoxy to fabricate different types of composite coatings (named EP-G a , EP-G b , EP-GO and EP-GS, respectively) as well as the pure waterborne epoxy coating was fabricated for comparison. The corrosion behaviors of as-fabricated coatings with and without graphene sheets were systematically characterized via potential, impedance testing and Tafel curves by immersing in 3.5 wt % NaCl solution. It was remarkable to point out that EP-G a composite coating could possess a promising long-term corrosion protection capability. The corrosion protection mechanism of graphene-based composite coatings were verified as the barrier effect of impermeable graphene sheets that confirmed by the analysis of corrosion products. Moreover, the scanning vibrating electrode technique in-depth revealed the relationship between the graphene structures and corrosion performances of the composite coatings. With the occurrence of commercialized application of graphene-based coatings, these works displayed a suitable approach toward the long-term corrosion behavior, which was able to be extended to other two-dimensional materials for anti-corrosion coatings. [ABSTRACT FROM AUTHOR]