Evolution Mechanism of Metallic Dioxide MO₂ (M = Mn, Ti) from Nanorods to Bulk Crystal: First-Principles Research

Using first-principle calculations, the surface energy, cohesive energy, and electronic properties of α -MnO 2 and rutile TiO 2 nanorods and microfacets were investigated and clarified to, in the first instance, determine the evolution mechanism. The results show that the surface energies of α -MnO 2 nanorods and microfacets conform to function 1.0401 Jm −2 + N × 0.608 Jm −2 , while the surface energies of the rutile TiO 2 nanorods and microfacets are governed by a 1.0102 × 1.1997 rule. Their electronic properties, such as the Mulliken population and Mulliken charge, can only be normalized by their surface areas to attain a linear function. Meanwhile, the surface energy of α -MnO 2 with the nanostructure closely conforms to the function for normalized Mulliken population and Mulliken charge as f(x)=102.9×x+0.101 with an R2 value of 0.995. Thus, our research into the evolution mechanism affecting the surface effect of nanometer materials will be useful for investigating the intrinsic mechanism of the nanometer effect and doping process of metallic dioxide catalysts.