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The effectiveness of mesoporous SnO2nickel-decoration as a method for obtaining active electrode materials for bioethanol electrochemical oxidation and the way in which the embedment of a small amount of Black Pearls (BP) affects the electrocatalytic performances of Ni/SnO2systems were investigated. XPS analysis reveals the presence of NiO, Ni(OH)2and Ni2O3chemical species which favors the oxidation of bioethanol and improves the COxtolerance. Nickel deposition in a reducing environment does not affect the Sn chemistry and the mesoporosity but significantly increases SBET. A slight amount of BP enhances the SBETvalue and a induces a small contribution of larger pores appears. Tafel slopes of 80 mV decade−1were estimated for bioethanol oxidation at Ni/SnO2, which favorably compare to those reported in the literature. It was also found that BP incorporation leads to a decrease of the Tafel slope to 70 mV decade−1, without deleteriously affecting the stability of the electrocatalyst during long-term polarization. EIS results suggested that this improvement might be the combined effect of a lower electrical resistance, a higher specific surface area and a certain contribution from larger pores, which could lead to a better access of the bioethanol species to the electrocatalyst surface.

The electrochemical behavior of epinephrine at graphene-modified boron-doped diamond (GR/BDD) electrodes was studied in phosphate buffer solution within pH range from 4.6 to 10. Cyclic voltammograms, recorded for GR/BDD and boron-doped diamond (BDD) at pH 7, attest that, in the first case, the peak associated to the oxidation of epinephrine to adrenalinquinone is negatively shifted by around 350 mV and much sharper and higher. It appears that the presence of the graphene layer promotes the overall oxidation process. Additional investigations carried out at different pH, point out that the best sensitivity of GR/BDD toward epinephrine oxidation is obtained at pH 7. The calibration plot at pH 7 exhibited a certain decrease of the sensitivity from a rather high value 3.00 uA cm[?]2 uM[?]1 within the concentration range 1 uM-10 uM to a satisfactory one of 0.45 uA cm[?]2 uM[?]1 at higher epinephrine content, suggesting that GR/BDD electrode may be used for trace analysis. Epinephrine detection in the presence of uric acid, with relevance for the detection of biological compounds, can be achieved at relatively low or high pH, in which cases, two peaks situated at 0.229 V and 0.356 V, corresponding to epinephrine and uric acid oxidation, are evidenced.

Mesoporous nanosized powders with single-phase solid solution fluorite structure in the ternary oxide zirconia−yttria−titania system, with titania contents from 0 to 30 mol %, were synthesized by the self-assembling method associated with hydrothermal treatment using cetyltrimethylammonium bromide (CTAB) as the surfactant-directing agent and pore-forming agent. The resulting materials were characterized by X-ray diffraction (XRD), Raman spectroscopy (Raman), scanning and transmission electron microscopy (SEM and TEM), thermogravimetric analysis (TG-DTG), N2adsorption/desorption isotherms (BET), and X-ray photoelectron spectroscopy (XPS). The as-synthesized mesoporous nanoparticles are single-phase crystallites with a crystal size and diameter between 6 and 12 nm and mean pore size around 2 nm. The specific surface area of the as-synthesized mesoporous samples after calcination at 550 °C remains as high as 140 m2/g. All spectroscopic methods clearly confirm the homogeneous incorporation of Ti4+in the lattice of the nanocrystallites, forming a single-phase solid solution with fluorite structure and modifying the absorption spectra of the nanocrystallites. The mesoporous solid solution nanoparticles show significant activity in catalytic oxidation of methane in the range 650−750 °C.

The electrochemical behavior of epinephrine at graphene-modified boron-doped diamond (GR/BDD) electrodes was studied in phosphate buffer solution within pH range from 4.6 to 10. Cyclic voltammograms, recorded for GR/BDD and boron-doped diamond (BDD) at pH 7, attest that, in the first case, the peak associated to the oxidation of epinephrine to adrenalinquinone is negatively shifted by around 350 mV and much sharper and higher. It appears that the presence of the graphene layer promotes the overall oxidation process. Additional investigations carried out at different pH, point out that the best sensitivity of GR/BDD toward epinephrine oxidation is obtained at pH 7. The calibration plot at pH 7 exhibited a certain decrease of the sensitivity from a rather high value 3.00 μA cm−2μM−1within the concentration range 1 μM–10 μM to a satisfactory one of 0.45 μA cm−2μM−1at higher epinephrine content, suggesting that GR/BDD electrode may be used for trace analysis. Epinephrine detection in the presence of uric acid, with relevance for the detection of biological compounds, can be achieved at relatively low or high pH, in which cases, two peaks situated at 0.229 V and 0.356 V, corresponding to epinephrine and uric acid oxidation, are evidenced.

In the present work, polytyramine (PTy) and cobalt oxide (Co3O4) were used as substrates for platinum electrodeposition, in order to obtain electrode systems with electrocatalytic properties. PTy and Co3O4were previously electrochemically deposited on graphite and boron-doped diamond (BDD) supports, respectively. Anodic oxidation of methanol was used as a test-reaction for assessing possible functional effects of the substrate on the electrochemical behavior of the Pt particles. It was found that, when deposited on PTy or cobalt oxide, the electrocatalyst exhibits higher activity and is less susceptible to fouling, via strong adsorption of reaction intermediates. X-ray photoelectron spectroscopy (XPS) measurements suggested that these features can be ascribed to the presence of --OH functional groups at the surface of the Pt particles. It was also found that electrodeposition of platinum on BDD resulted only in metallic Pt and Pt(OH)2, whereas when graphite was used as substrate the presence of platinum oxides was also evident. During prolonged anodic oxidation of methanol, a higher stability of the --OH groups from the platinum surface was observed for graphite-supported Pt particles, compared to the case when bare BDD was used as support.