The spontaneous directional transformations of the layers and chemical bonds: a study combining first-principles calculations and experiments

We synthesized PtTe2 nanoflakes via chemical transformation utilizing Te nanoflakes as templates. Aberration-corrected transmission electron microscopy confirmed this assertion and revealed the distinctive in-plane layered structure of the synthesized PtTe2 nanoflakes. The transformation process and reaction mechanisms were investigated using particle swarm optimization algorithms in combination with first-principles density functional calculations. According to the calculations, it was found that the initial chemical bonds automatically transition to the cross-sectional direction, representing the first experimental confirmation of the spontaneous directional transformation of layers and chemical bonds within multivalent Te layers. It is noteworthy that this transformation exhibits a significant dimension-dependent characteristic. This study has broadened the range of growth processes for two-dimensional materials, contributing to a better understanding of transformation behaviors between chemical stimuli and nanocrystals.