Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University Olomouc, tř. 17. listopadu 12, 77 146 Olomouc, Czech Republic.
Nanoscale. 2018 May 17;10(19):8979-8988. doi: 10.1039/c8nr00329g.
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.
纳米材料具有高的比表面积，其表面性质显著影响其特性和应用潜力。黑磷（BP）的单层磷烯是继石墨烯发现后第一个被制备出来的同原子二维材料。磷烯的结构类似于石墨烯的蜂窝状排列，但它的层是褶皱的，具有高度各向异性。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。我们使用反气相色谱法测量了 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，它具有显著的酸碱相互作用的贡献。我们进一步测量了挥发性有机化合物在 BP 上的吸附焓，并使用密度泛函理论计算对其进行了合理化。极性分子表现出更高的亲和力，因为偶极-偶极相互作用对分子-表面键合有显著贡献，因为 BP 的褶皱表面比石墨烯的扩散势垒更高，阻碍了分子的面内运动，并支持分子偶极在更长距离上的相互取向，这与石墨烯不同。
