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The effects of cerium addition on the physical-chemical properties and CO oxidation activity of nanocomposite MnCeOx catalysts (0 ≤ χCe ≤ 1) have been assessed. The kinetics of the CO oxidation on a typical nanocomposite MnCeOx catalyst (M5C1) were probed by temperature programmed catalytic reaction tests in the range of 293-533K. A systematic study of the interaction pattern of the catalyst with reagent and product molecules shows easy reactivity of surface oxygen to CO, low mobility of lattice oxygen and weak surface affinity to CO2. Systematic evidences on mechanism and intermediates signal an extrafacial redox path, triggered by the abstraction of oxygen atoms in the neighbouring of surface-active MnIV sites, and sustained by O2 species adsorbed on the resulting O-vacancies. A Langmuir-Hinshelwood (L-H) type reaction mechanism leads to a formal kinetic model fully predicting the CO oxidation functionality of the MnCeOx catalysts. [ABSTRACT FROM AUTHOR]

A planar electrochemical sensor, based on flower-like CuO nanostructures growth 'in situ' on a commercial screen printed carbon electrode, was fabricated by an easy and effective technique and employed for the non-enzymatic determination of glucose. The prepared CuO nanostructures were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The carbon electrode modification with CuO was optimized by investigating the effect of the number of deposition cycles of precursor and their concentration. The electrodes modified by in situ growth of CuO were compared to an electrode prepared by simple deposition of CuO powder previously synthesized by the same technique. Cyclic voltammetric and chronoamperometric tests demonstrated that the in situ growth of CuO leads to excellent electrochemical performance toward glucose oxidation in 0.1 M KOH solution. The best sensor, if operated at an applied potential of 0.6 V, has a sensitivity of 1460 μA·mM·cm and a 2.5 μM detection limit (at an S/N ratio of 3). Tests carried out within six months revealed an excellent long-term stability. This suggests that the method applied to modify the carbon electrode represents a useful tool for fabrication of an inexpensive and reliable non-enzymatic glucose sensor. [ABSTRACT FROM AUTHOR]

Dendrimer-functionalized multi-walled carbon nanotubes (MWCNT) for heavy metal ion removal from wastewaters were developed. Triazole dendrimers (TD) were built directly onto the carbon nanotube surface by successive click chemistry reactions affording the zero- and first-generation dendrimer-functionalized MWCNT (MWCNT-TD1 and MWCNT-TD2). The Moedritzer-Irani reaction carried out on the amino groups present on the MWCNT-TD2 sample gave the corresponding α-aminophosphonate nanosystem MWCNT-TD2P. Both MWCNT-TD2 and MWCNT-TD2P nanosystems have been characterized by physical, chemical, and morphological analyses. Their chelating abilities towards the toxic metal ions Pb, Hg, and Ni and the harmless Ca ion have been experimentally evaluated in the two different sets of experiments and at the salt concentrations of 1 mg/mL or 1 μg/mL by inductively coupled plasma mass spectrometry (ICP-MS). The results of these studies pointed out the interesting chelating behavior for the phosphonated nanosystem towards the Hg ion. The complexation mode of the best chelating system MWCNT-TD2P with mercury was investigated through density functional theory (DFT) calculations, suggesting a chelation mechanism involving the two oxygen atoms of the phosphate group. The synthesized dendrimers, supported on the multi-walled carbon nanotubes, have shown the potential to be used for the selective toxic metal ion removal and recovery. [ABSTRACT FROM AUTHOR]

The catalytic properties of Pt supported on zeolite P (ZP)-based materials for the preferential CO oxidation in hydrogen atmosphere under mild conditions (from room temperature to 150 °C), have been investigated. Pt catalysts (1-4 wt%) supported on a zeolitized pumice support (Z-PM) have been prepared. A series of bimetallic Pt-Fe on ZP, having 2 wt% Pt and different Fe loading (0.5-4 wt%), have been also prepared and used as model catalysts. A detailed characterization of the catalysts has been carried out by means of surface area and porosity measurements, X-ray diffraction, scanning electron microscopy and transmission electron microscopy in order to investigate the morphological and microstructural properties of both support and catalytic system. Pt/Z-PM exhibited complete CO conversion with 55 % selectivity at temperatures as low as 50 °C, with no noticeable degradation of the catalytic performances, indicating that the Fe content present as an impurity in the zeolitized pumice support allows to obtain catalysts characterized by high activity and stability. On the basis of the characterization and kinetic tests, hypotheses on the role of Fe promoter have been formulated. [ABSTRACT FROM AUTHOR]