Alexander D. Modestov

The incorporation of titania into modified silicates for solar photodegradation of aqueous species

A new class of sol-gel-derived photocatalytic materials has been synthesized and used in solar-assisted photodegradation studies. The materials are comprised of a homogeneous dispersion of commercial TiO2 powder into silica and organically modified silicate (Ormosil) hosts. The efficiency of the photocatalytic properties of these TiO2-containing materials was determined by their relative performance in the solar photodecomposition of aqueous rhodamine B. The improved adsorption properties of the modified materials compared to commercial TiO2 increase the photodecomposition rate and the buoyancy properties, although excess hydrophobicity decreases the wetted section of the catalyst and its photocatalytic performance. These materials can be used as floatable catalysts for solar-assisted water purification.

Graphite photoelectrochemistry: Part 4. Photoelectrochemical studies of quinones in acetonitrile at HOPG electrodes

Stationary photocurrents for reduction of different quinone compounds (benzoquinone, 1,4-naphthoquinone, and 9,10-phenanthroquinone) at irradiated highly oriented pyrolytic graphite (HOPG) electrodes in CH3CN are reported. Excitation of hot electrons in a graphite electrode by UV‐vis light absorption and subsequent hot electron transfer to an acceptor species (quinones) in the electrolyte is assumed to be the source of the photocurrent. This mechanism is supported by photocurrent‐potential dependence and photocurrent light action spectra. The effect of the potential drop in the space charge layer of graphite electrodes on photocurrent generation was evaluated by the comparison of photocurrent generation at basal and edge plane HOPG orientations and glassy carbon (GC) electrodes.