Electrochemical measurements show that the enzyme glucose oxidase (GO) is adsorbed on the surface of TiO2 without apparently changing the flat band potential of the semiconductor, indicating that it does not cause a change of the energy of conduction band electrons. on the othr hand, it is observed that GO markedly increases the efficiency of the two electron reduction of O2 to H2O2 which is accumulated in the solution phase. ESR spin trapping investigations indicate that GO favors the formation of OH radicals, due to either the inhibition of charge recombination processes oro to H2O2 reduction by conduction band electrons. Accordingly, photooxidation of different alcohols due to the corresponding radical species is also enhanced in the presence of GO. The photooxidation of 1,2 propandiol on TiO2/GO is regioselective in that (i) partial oxidation to hydroxyacetone is observed and (ii) no mineralization (full combustion to CO2) of the substrate occurs. These facts are of particular interest in the field of studies concerning the design of new photocatalytic systems with enhanced activity and controllable oxidative power.
PHOTO-ELECTRO-CHEMICAL PROPERTIES OF TiO2 MEDIATED BY THE ENZYME GLUCOSE OXIDASE
MOLINARI, Alessandra;SAMIOLO, Luca;MALDOTTI, Andrea
2005
Abstract
Electrochemical measurements show that the enzyme glucose oxidase (GO) is adsorbed on the surface of TiO2 without apparently changing the flat band potential of the semiconductor, indicating that it does not cause a change of the energy of conduction band electrons. on the othr hand, it is observed that GO markedly increases the efficiency of the two electron reduction of O2 to H2O2 which is accumulated in the solution phase. ESR spin trapping investigations indicate that GO favors the formation of OH radicals, due to either the inhibition of charge recombination processes oro to H2O2 reduction by conduction band electrons. Accordingly, photooxidation of different alcohols due to the corresponding radical species is also enhanced in the presence of GO. The photooxidation of 1,2 propandiol on TiO2/GO is regioselective in that (i) partial oxidation to hydroxyacetone is observed and (ii) no mineralization (full combustion to CO2) of the substrate occurs. These facts are of particular interest in the field of studies concerning the design of new photocatalytic systems with enhanced activity and controllable oxidative power.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
