Local Detection of Photoelectrochemically Produced H2O2 with a Wired HorseradishPeroxidase Microsensor

摘要

A hydrogen peroxide (H2O2) microsensor has been prepared on a 7 um carbon fibermicrodisk, using horseradish peroxidase (HRP) immobilized in a poly(4-vinylpyndine) based redox hydrogel having Os(bpy)2Cl(2+/2+) redox centers. Because of radial diffusion of the electrons through the hydrogel, the sensor's steady state current density for H2O2 electroreduction was 0.17 mA/ sq cm at .000l M H202, more than 10 times that of a 3 mm macroelectrode. With the microsensor positioned 50 micrometers from the surface, H2O2 production by photogenerated hole oxidation of water and photogenerated electron reduction of molecular oxygen was monitored independently on a partially TiO2 coated ITO (indium tin oxide) glass. H2O2 was produced primarily by photoelectroreduction of dissolved oxygen on the ITO glass, with a lesser amount of H2O2 being produced by photoelectrooxidation of water on the TiO2 film.