Two-dimensional photocatalytic materials with unique properties have been well reported in recent decades. However, the strategy of controlling the photocatalytic process is still ongoing. Herein, Janus X2PAs (X = Si,...

Switching polarization via inter-layer sliding or heterostructural inversion in two-dimensional SnS/SnSSe ferroelectric heterostructures with enhanced vertical polarization and ultra-low switching barriers.

Development of piezoelectric materials is limited partly due to the incompleteness of internal mechanism and the lack of vertical piezoelectricity. Herein, we theoretically identify the stable MoTO (T = S, Se, or Te) monolayers and bilayers. When two elements are given but another element can be changed, the larger the electronegativity difference ratio R ratio is, the stronger the piezoelectricity will be. Vertical piezoelectric coefficient d 33 of the MoTeO bilayer reaches 38.907 pm/V, which is 12 times larger than that of the bulk GaN. The “active asymmetric electron-transfer” strategy mainly contributes to the spontaneous remarkable piezoelectricity of MoTO. Importantly, we proposed the new method for calculating the piezoelectric coefficients of two-dimensional (2D) materials, which corresponds to the fact that 2D materials have a certain thickness. This study not only provides novel extraordinary candidates for energy conversion and touch-sensor nanodevices but also promotes a deeper understanding of piezoelectricity of 2D materials.

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