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Degradation behaviors of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) layers on NiO in the presence of H2O at ambient pressure and dark conditions were studied using X‐ray photoelectron spectroscopy (XPS). Upon H2O exposure at 120 °C, partial oxidation of P3HT together with molecular water incorporation, but with the maintained local ring‐structure, were deduced by XPS. Valence band spectra of XPS evidenced that the partial oxidation of P3HT local structure could alter π‐conjugation systems of P3HT layers, forming additional electronic states close to its original highest occupied molecular orbital. For comparison, P3HT surface was also exposed to O2, and no change in the S 2p and C 1s spectra was found by O2 exposure at 120 °C, implying that H2O plays a major role at the initial stage of P3HT oxidation. Copyright © 2014 John Wiley & Sons, Ltd.

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We studied the adsorption of toluene and its photodecomposition by TiO 2 surfaces under UV irradiation using P-25 samples subjected to two different treatments. In order to shed light on the elementary steps of the photocatalytic decomposition of toluene, we employed X-ray photoelectron spectroscopy (XPS). A higher population of the surface OH-group of TiO 2 increased the adsorption reactivity and initial rate of the photodecomposition of toluene. We also identified more efficient accumulation of toluene on the surface of TiO 2 with high concentrations of OH-groups via XPS.