Novel Two-Dimensional Tellurium Allotropes from the First-principles Predication*

Very recently, the successful predication and synthesis of α-, β-, and γ- tellurene have extended the two-dimensional (2D) materials family to group-VI elements and provided new candidates for next-generation electronic and optoelectronic applications. Based on our previous work,we have furtherpredicted 33 newly 2D tellurium allotropes with mono- and multi-layers of tellurium atoms using the particle-swarm crystal structure searches methods andthe first-principles calculations. Thestabilityof these 2D structures is well verified by the total energy calculations, as well as phononspectrum calculations.Four kinds of new allotropes are found energeticallymore stable than the β-Te phase which already has been synthesized experimentally.Among these structures, we found three of them exhibittopological properties and two with superconductorproperties. The present findings enlarge the family of tellurene and will stimulate future experimental studies to synthesize novel group-VI 2D materials.