Nanomaterials have a high surface-to-mass ratio and their surface properties significantly affect their features and application potential. Phosphorene, a single layer of black phosphorus (BP), was the first homoatomic two-dimensional material to be prepared after the discovery of graphene. The structure of phosphorene resembles the honeycomb arrangement of graphene, but its layers are buckled and highly anisotropic. We studied how this difference affects the surface properties of BP, namely the free surface energy and adsorption affinity of various organic molecules. Using inverse gas chromatography, we measured the total surface free energy of BP powder to be 90 mJ m⁻² and showed that it was dominantly determined by dispersion forces, but, unlike on graphene, with a notable contribution from specific acid–base interactions. We further measured adsorption enthalpies of volatile organic compounds on BP and rationalized them using density functional theory calculations. Polar molecules showed an increased affinity due to a significant contribution of dipole–dipole interactions to the molecule–surface bonding, because the buckled surface of BP causes higher diffusion barriers than those on graphene, hinders molecular in-plane motion and supports mutual orientation of molecular dipoles over longer distances, in contrast to graphene.

中文翻译：

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褶皱各向异性表面在黑磷表面的作用及吸附性能

纳米材料具有高比表面积，其表面性质显着影响其特性和应用潜力。磷烯是单层黑磷（BP），是石墨烯发现后第一个制备的同原子二维材料。磷烯的结构类似于石墨烯的蜂窝状排列，但其层是弯曲的且高度各向异性。我们研究了这种差异如何影响 BP 的表面性质，即各种有机分子的自由表面能和吸附亲和力。使用反气相色谱法，我们测量了 BP 粉末的总表面自由能为 90 mJ m ⁻²，并表明它主要由色散力决定，但与石墨烯不同，特定酸碱相互作用的显着贡献。我们进一步测量了 BP 上挥发性有机化合物的吸附焓，并使用密度泛函理论计算对其进行了合理化。由于偶极-偶极相互作用对分子-表面键合的显着贡献，极性分子表现出增加的亲和力，因为 BP 的弯曲表面比石墨烯上的扩散势垒更高，阻碍分子面内运动并支持分子的相互取向与石墨烯相比，偶极子的距离更长。