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

Stationary photocurrents for reduction of different quinone compounds (benz oquinone, 1,4-naphthoquinone, and 9,10-phenanthroquinone) at irradiated hig hly oriented pyrolytic graphite (HOPG) electrodes in CH3CN are reported. Ex citation of hot electrons in a graphite electrode by W-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 mecha nism is supported by photocurrent-potential dependence and photocurrent lig ht action spectra. The effect of the potential drop in the space charge lay er of graphite electrodes on photocurrent generation was evaluated by the c omparison of photocurrent generation at basal and edge plane HOPG orientati ons and glassy carbon (GC) electrodes. (C) 2000 Elsevier Science B.V. All r ights reserved.