Gao Yuying, Zhu Jian, An Hongyu, Yan Pengli, Huang Baokun, Chen Ruotian, Fan Fengtao, Li Can
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy , Zhongshan Road 457, Dalian 116023, China.
University of Chinese Academy of Science , Beijing, 100049, China.
J Phys Chem Lett. 2017 Apr 6;8(7):1419-1423. doi: 10.1021/acs.jpclett.7b00285. Epub 2017 Mar 16.
Phase junction is often recognized as an effective strategy to achieve efficient charge separation in photocatalysis and photochemistry. As a crucial factor to determine the photogenerated charges dynamics, there is an increasingly hot debate about the energy band alignment across the interface of phase junction. Herein, we reported the direct measurement of the surface potential profile over the interface of TiO phase junction. A built-in electric field up to 1 kV/cm from rutile to anatase nanoparticle was detected by Kelvin Probe Force Microscopy (KPFM). Home-built spatially resolved surface photovoltage spectroscopy (SRSPS) supplies a direct evidence for the vectorial charge transfer of photogenerated electrons from rutile to anatase. Moreover, the tunable anatase nanoparticle sizes in TiO phase junction leads to high surface photovoltage (SPV) by creating completely depleted space charge region (SCR) and enhancing the charge separation efficiency. The results provide a strong basis for understanding the impact of built-in electric field on the charge transfer across the interface of artificial photocatalysts.
相结通常被认为是在光催化和光化学中实现高效电荷分离的有效策略。作为决定光生电荷动力学的关键因素，关于相结界面处的能带排列存在越来越激烈的争论。在此，我们报道了对TiO相结界面上表面电势分布的直接测量。通过开尔文探针力显微镜（KPFM）检测到从金红石到锐钛矿纳米颗粒的高达1 kV/cm的内建电场。自制的空间分辨表面光电压光谱（SRSPS）为光生电子从金红石到锐钛矿的矢量电荷转移提供了直接证据。此外，TiO相结中可调节的锐钛矿纳米颗粒尺寸通过创建完全耗尽的空间电荷区（SCR）并提高电荷分离效率，导致高表面光电压（SPV）。这些结果为理解内建电场对人造光催化剂界面电荷转移的影响提供了有力依据。
