Kim Yong H, Lee Su Y, Umh Ha N, Song Hyeon D, Han Jeong W, Choi Jang W, Yi Jongheop
School of Chemical and Biological Engineering, Institute of Chemical Process, World Class University Program of Chemical Convergence for Energy & Environment, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.
Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea.
ACS Appl Mater Interfaces. 2020 Apr 1;12(13):15239-15245. doi: 10.1021/acsami.0c00669. Epub 2020 Mar 17.
Z-scheme transfer is an ideal photocatalytic system with stronger redox ability, but its design and construction still lack understanding. Herein, the work function difference and the band bending are found to be the determining factors for the construction of the Z-scheme transfer mechanism of photoexcited charges in TiO/WO. The control of work function and band bending achieved by carbon insertion results from the hybridization of orbitals and redistribution of electron density, as demonstrated by ultraviolet photoelectron spectroscopy and photocatalytic analysis. The heterojunction system, TiO/WO, with controlled work function and band bending, shows 2 times faster OH radical formation rate (0.011 μmol min) compared to the undisturbed system. First-principles calculation reveals that the changes in work function and band bending result in an interfacial electric field, which shifts the charge transfer mechanism from type II to Z-scheme. This work proves that the design of work function and band bending allows reconstructing charge transfer mechanism by forming the interfacial electric field in heterojunction systems.
Z 型转移是一种具有较强氧化还原能力的理想光催化体系，但其设计和构建仍缺乏深入理解。在此，发现功函数差和能带弯曲是 TiO/WO 中光激发电荷 Z 型转移机制构建的决定因素。通过碳插入实现的功函数和能带弯曲的控制源于轨道杂化和电子密度的重新分布，这已由紫外光电子能谱和光催化分析所证实。具有可控功函数和能带弯曲的异质结体系 TiO/WO 显示出与未受干扰体系相比快 2 倍的羟基自由基生成速率（0.011 μmol min）。第一性原理计算表明，功函数和能带弯曲的变化导致界面电场的产生，从而使电荷转移机制从 II 型转变为 Z 型。这项工作证明，功函数和能带弯曲的设计能够通过在异质结体系中形成界面电场来重构电荷转移机制。
