Wang Guangzhao, Li Zongfeng, Wu Weikang, Guo Hao, Chen Cong, Yuan Hongkuan, Yang Shengyuan A
Key Laboratory of Micro Nano Optoelectronic Devices and Intelligent Perception Systems, Key Laboratory of Extraordinary Bond Engineering and Advanced Materials Technology of Chongqing, School of Electronic Information Engineering, Yangtze Normal University, Chongqing 408100, China.
Phys Chem Chem Phys. 2020 Nov 14;22(42):24446-24454. doi: 10.1039/d0cp03925j. Epub 2020 Oct 21.
The construction of a heterostructure (HS) is an effective strategy to modulate the desired properties of two-dimensional (2D) materials and to extend their applications. In this paper, based on the density functional theory, we predict a metal-free type-II HS formed by h-BN and CN single layers. The h-BN/CN HS possesses a smaller bandgap than individual h-BN and CN single layers, and it exhibits excellent visible light absorption. Importantly, its band edge positions satisfy the requirements for spontaneous water-splitting. With the assistance of the built-in electric field across the HS and the band offset, the photoinduced carriers can be readily spatially separated. Free energy calculations indicate the high catalytic activity for water oxidation and reduction reactions. The performance can be further enhanced by strain, which modulates the bandgap and the band edge positions of the HS. The band alignment may undergo a transition from type-I to type-II under strain, offering an effective switch for the reaction. The appropriate bandgap, suitable band edge positions, and effective carrier separation make the h-BN/CN HS a promising candidate for use as a photocatalyst in water-splitting.
构建异质结构（HS）是调控二维（2D）材料所需性能并拓展其应用的有效策略。本文基于密度泛函理论，预测了一种由h-BN和CN单层形成的无金属II型HS。h-BN/CN HS的带隙比单独的h-BN和CN单层更小，并且表现出优异的可见光吸收性能。重要的是，其带边位置满足自发水分解的要求。借助HS中的内建电场和带隙偏移，光生载流子能够很容易地在空间上分离。自由能计算表明其对水氧化和还原反应具有高催化活性。应变可进一步提高其性能，因为应变能调节HS的带隙和带边位置。在应变作用下，能带排列可能从I型转变为II型，为反应提供一个有效的开关。合适的带隙、适宜的带边位置以及有效的载流子分离使得h-BN/CN HS成为用于水分解光催化剂的有潜力候选材料。
