Abstract
Using first-principle calculations, the surface energy, cohesive energy, and electronic properties of α-MnO2 and rutile TiO2 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-MnO2 nanorods and microfacets conform to function 1.0401 Jm−2 + N × 0.608 Jm−2, while the surface energies of the rutile TiO2 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-MnO2 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.
Highlights
TiO2, which is a vital inorganic functional nanomaterial, has been widely used in down-flop pigments, ultraviolet screening, photoelectric conversion, photocatalysis, and so on [1]
The evolution mechanism of metallic dioxide MO2 (M = Mn, Ti) from nanorods to bulk crystal has been investigated by first-principles calculation
For α-MnO2, it is found that the surface energy conforms to the function: Y = A + N × B, where A is equal to 1.0401 Jm−2, B is equal to 0.6648 Jm−2, and N is equal to a positive integer of no more than 6
Summary
TiO2, which is a vital inorganic functional nanomaterial, has been widely used in down-flop pigments, ultraviolet screening, photoelectric conversion, photocatalysis, and so on [1]. MnO2 is a popular and cost-effective material for the removal of pollutants in air, water, and industry [2] Both have been widely investigated and improved to enhance their catalytic performance, such as by doping with metallic elements [1, 3], incorporation into carbon nanotubes [4], and manufacturing with a nanometer structure [5]. In the nanocrystallization process, the TiO2 and MnO2 nanometer materials exhibit additional surface and nanometer effects they have the same components and skeleton units as the bulk morphology. Both have been successfully applied to catalytic redox for some pollutants. Regarding the decomposition of CO, Chen et al [8]
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