13:30 〜 13:45
▲ [21p-N302-2] Peering into Carrier Transport Mechanism of Anatase/Rutile Core/Shell TiO2 NFs Photocatalysts by Photo-Kelvin Probe Force Microscopy
キーワード：TiO2 core/shell heterostructure, photo-kelvin probe force microscopy, carrier transport
Photocatalysis has raised a lot of interests due to the contribution to renewable energy production and organic pollutant decomposition. Among various photocatalysts, TiO2 is widely used due to its advantages, such as highly active photocatalytic property, chemical, and thermal stability, environment-friendly, non-toxic and low cost. Generally, anatase TiO2 is much active than rutile TiO2, the anatase/rutile mixed-phase TiO2 seems to have superior photocatalytic performance. It is known that the band alignment between two phases is a crucial factor for carrier separation after photogeneration. In this study, we demonstrate a method for measuring surface potential shifts of core/shell TiO2 nanofibers (NFs) by photo-Kelvin probe force microscopy (photo-KPFM) to reveal assessment of surface charge accumulation after light irradiation. According to the results, core-shell TiO2 facilitate the separation of electron-hole pair, in which anatase acts as an electron acceptor and rutile acts as a hole trap. The Pt nanoparticles decorated anatase/rutile core/shell TiO2 NFs could promote an obvious accumulation of electron on the surface and give rise to a large surface potential shift. The surface potential shift is well correlated to the photodegradation activity. Based on the studies, we can construct a band structure model of anatase/rutile core/shell TiO2 NFs. For the anatase and rutile TiO2, the aligned conduction bands allow the electron injecting between two phases seamlessly. For the valence band edges, the small offset between anatase TiO2 and rutile TiO2 impedes the holes inject from rutile to anatase. The decorated Pt NPs which contact with rutile TiO2 forms a Schottky interface; therefore, the electrons can further inject from the semiconductor to the metal.