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 carbonate and acetonitrile has been studied by in-situ Fourier transform IR spectroscopy. Both the solvents and solutes are unstable against oxidative decomposition at the photoexcited n-TiO2 (anatase) electrode. The main oxidation product is CO2. This is formed via photoinduced decarboxylation of propylene carbonate or, alternatively, via the photoanodic reaction of acetonitrile and trace water. The anodic breakdown of the electrolyte solutions studied on the photoexcited n-TiO2 electrode generally resembles that occuring on platinum or glassy carbon anodes at high potentials in the dark. Addition of iodide to the electrolyte solutions suppresses the photoelectrochemical decomposition to CO2.