Interfacial polarization is critical in electromagnetic (EM) wave absorption for dielectric materials. The underlying mechanisms and related factors of the interfacial polarization, however remain veiled, refraining the advance of dielectric absorbers with enhanced attenuation. Herein, two-dimensional (2D) SnO nanosheets have been used as a template, whose dominating interface evolves from SnO-(0 0 1)/SnO-(1 1 0) to SnO-(1 1 0)/SnO₂-(1 0 1) and SnO₂-(1 0 1)/SnO₂-(2 1 1) via controllable oxidation. Combined off-axis electron holography and first-principle calculations indicate that larger difference in the work function of the SnO-(1 1 0)/SnO₂-(1 0 1) (1.986 eV) compared with those of the SnO-(0 0 1)/SnO-(1 1 0) and SnO₂-(1 0 1)/SnO₂-(2 1 1) (0.338 eV and 0.534 eV, respectively) gives rise to distinctive charge density distribution. As such enhanced interfacial polarization can be achieved for favorable electromagnetic wave absorption of the SnO/SnO₂ heterojunctions. This study not only provide a versatile method to fabricate 2D heterojunctions with tuned interfaces, correlations among work function, charge separation and interfacial polarization are also established, which is instructive for electric polarity manipulation for various applications.

界面极化对于介电材料的电磁（EM）波吸收至关重要。然而，界面极化的基本机理和相关因素仍然被掩盖，从而抑制了具有增强衰减的介电吸收器的发展。在此，二维（2D）SnO纳米片已用作模板，其主要界面从SnO-（0 0 1）/ SnO-（1 1 0）演变为SnO-（1 1 0）/ SnO _2-（ 1 0 1）和SnO _2-（1 0 1）/ SnO _2-（2 1 1）通过可控制的氧化。结合离轴电子全息图和第一性原理计算表明，SnO-（1 1 0）/ SnO _2-（1 0 1）（1.986 eV）的功函数与SnO-（0 0 1）/ SnO-（1 1 0）和SnO ₂-（1 0 1）/ SnO _2-（2 1 1）（分别为0.338 eV和0.534 eV）产生独特的电荷密度分布。这样，可以实现增强的界面极化，以有利于SnO / SnO ₂异质结的电磁波吸收。这项研究不仅提供了一种制造具有调谐界面的二维异质结的通用方法，而且还建立了功函数，电荷分离和界面极化之间的相关性，这对于各种应用中的极性操纵具有指导意义。