IN-SITU FTIR STUDY OF ANODIC PHOTOREACTIONS AT THE N-TIO2 (ANATASE) ELECTRODE IN APROTIC ELECTROLYTE-SOLUTIONS

The photoanodic breakdown of LiCl4 and LiBF4 solutions in propylene ca rbonate and acetonitrile has been studied by in-situ Fourier transform IR spectroscopy. Both the solvents and solutes are unstable against o xidative decomposition at the photoexcited n-TiO2 (anatase) electrode. The main oxidation product is CO2. This is formed via photoinduced de carboxylation of propylene carbonate or, alternatively, via the photoa nodic reaction of acetonitrile and trace water. The anodic breakdown o f the electrolyte solutions studied on the photoexcited n-TiO2 electro de generally resembles that occuring on platinum or glassy carbon anod es at high potentials in the dark. Addition of iodide to the electroly te solutions suppresses the photoelectrochemical decomposition to CO2.