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Graphite electrodes were modified with specifically designed Os-complex modified electrodeposition polymers exhibiting a formal potential of the polymer-bound complex of about 0 to 20 mV (vs. Ag/AgCl/3 M KCl) which is only about 100 mV anodic of the formal potential of pyrroloquinoline quinone (PQQ) in PQQ-dependent glucose dehydrogenase (PQQ-GDH). The efficiency of wiring the polymer-entrapped PQQ-GDH was dependent on the nature of the polymer backbone, the crosslinking with bifunctional crosslinkers and the co-entrapment of multi-walled carbon nanotubes. Due to the limited long-term stability a new polymer synthesis strategy was adapted using the same Os-complex but providing enhanced crosslinking capabilities by introducing epoxide functions at the polymer backbone. Related bioelectrodes showed enhanced glucose-dependent current and a stability of at least 3 days of continuous operation. [ABSTRACT FROM AUTHOR]

Surface-modified TiO2 photocatalysts were synthesized by a photosynthetic route involving visible-light-induced (λ> 455 nm) activation of benzene and toluene at the surface of TiO2 leading to the formation of carbonaceous polymeric deposits. IR spectroscopic and photoelectrochemical experiments showed that the mechanism of the photosynthetic reactions involves intra-bandgap surface states at TiO2 related to surface OH groups interacting with adsorbed aromatic molecules. The photosynthesized surface-modified TiO2 materials exhibited enhanced activity, relative to pristine TiO2, in photocatalytic degradation (and complete mineralization) of 4-chlorophenol. The improvement was pronounced particularly under visible-light (λ>455 nm) irradiation with the relative initial photodegradation rate enhanced by a factor of four. The surface-modified photocatalysts exhibited good stability under the operating conditions, and the optimum carbon content was approximately 0.5 wt%. Mechanistic studies showed that the enhanced visible-light photodegradation of 4-chlorophenol is due to modified surface-adsorption properties that facilitate formation of a surface complex between titania and 4-chlorophenol, rather than due to any sensitizing effect of the carbonaceous deposits. The study highlights the importance of considering the interaction between pollutant molecules and the photocatalyst surface in heterogeneous photocatalysis, and possibly opens up a route for photosynthesis of further surface- modified photocatalysts with tuned surface properties. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) grown on carbon cloth substantially increased the surface area of the electrodes. Carbon cloths were pretreated with HNO3 vapor before CNTs growth and electrochemically oxidized afterwards. The CNT-modified carbon cloths were characterized using scanning electron microscopy, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Biofuel cells based on these CNT-modified electrode materials using Laccase from Trametes hirsuta and cellobiose dehydrogenase from Myriococcum thermophilium entrapped in specifically designed Os-complex modified redox polymers showed a power density of 5.87 µW/cm2 which is 125 fold enhanced as compared with electrodes prepared on untreated carbon cloth. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nanocrystalline rutile TiO2 powders were modified with small amounts of CuO x and FeO x clusters by impregnation and drying. [•] Photocatalytic degradation rate of 4-CP increased by the factor of 7 and 4 in case of CuO x and FeO x , respectively. [•] The visible light (λ >455nm) activity in 4-CP degradation was negligible. [•] Photopotential transient measurements confirm that CuO x and FeO x clusters act as co-catalysts for oxygen reduction. [Copyright &y& Elsevier]

Modified acrylate polymers are able to effectively exfoliate and stabilize pristine graphene nanosheets in aqueous media. Starting with pre-exfoliated graphite greatly promotes the exfoliation level. The graphene concentration is significantly increased up to 11 mg mL(-1) by vacuum evaporation of the solvent from the dispersions under ambient temperature. TEM shows that 75 % of the flakes have fewer than five layers with about 18 % of the flakes consisting of monolayers. Importantly, a successive centrifugation and redispersion strategy is developed to enable the formation of dispersions with exceptionally high graphene-to-stabilizer ratio. Characterization by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy shows the flakes to be of high quality with very low levels of defects. These dispersions can act as a scaffold for the immobilization of enzymes applied, for example, in glucose oxidation. The electrochemical current density was significantly enhanced to be approximately six times higher than an electrode in the absence of graphene, thus showing potential applications in enzymatic biofuel cells., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Surface-modified TiO 2 photocatalysts were synthesized by a photosynthetic route involving visible-light-induced (λ>455 nm) activation of benzene and toluene at the surface of TiO 2 leading to the formation of carbonaceous polymeric deposits. IR spectroscopic and photoelectrochemical experiments showed that the mechanism of the photosynthetic reactions involves intra-bandgap surface states at TiO 2 related to surface OH groups interacting with adsorbed aromatic molecules. The photosynthesized surface-modified TiO 2 materials exhibited enhanced activity, relative to pristine TiO 2 , in photocatalytic degradation (and complete mineralization) of 4-chlorophenol. The improvement was pronounced particularly under visible-light (λ>455 nm) irradiation with the relative initial photodegradation rate enhanced by a factor of four. The surface-modified photocatalysts exhibited good stability under the operating conditions, and the optimum carbon content was approximately 0.5 wt %. Mechanistic studies showed that the enhanced visible-light photodegradation of 4-chlorophenol is due to modified surface-adsorption properties that facilitate formation of a surface complex between titania and 4-chlorophenol, rather than due to any sensitizing effect of the carbonaceous deposits. The study highlights the importance of considering the interaction between pollutant molecules and the photocatalyst surface in heterogeneous photocatalysis, and possibly opens up a route for photosynthesis of further surface-modified photocatalysts with tuned surface properties., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)