First-principles Calculations On The Dynamic Properties Of Noble Metal Single-atom And Nanoclusters On WTe₂ Monolayer

In this paper,using first-principles calculations based on density functional theory,our study focuses on WTe₂,a kind of layered transition metal dichalcogenides?TMDs?,and its electronic properties are calculated theoretically.We systematically investigate the changes of the electronic structure properties of the n-doped,and p-doped WTe₂.Then,we study the adsorption and diffusion of a single noble metal Pt atom on the surface of WTe₂ monolayer,and the effect of n-and p-type doping on the diffusion barrier.In addition,we research the adsorption and growth of noble metal Au atoms on the surface of WTe₂ monolayer and the change after adsorption of oxygen molecules.The main contents and conclusions are as follows:?1?Although WTe₂ has been studied for decades,its structure and electronic properties have only recently been correctly described.There are three types of WTe₂.Our research focuses on Td-WTe₂,which is the most stable structure The structure of Td-WTe₂ constitutes triple-layers of covalently bonded Te–W–Te atomic planes,stacked along c-axis through weak van der Waals interactions.WTe₂ has a highly anisotropic electronic structure.Herein,using first-principles calculations based on density functional theory,we systematically investigate the kinetic behaviors of a single noble metal Pt atom on pristine,n-doped,and p-doped WTe₂ monolayer.Three types of diffusion,including pristine and Ta-doped?p-type?,as well as Re-doped?n-type?WTe₂ monolayer,are considered.The climbing image nudged elastic band?CI-NEB?method was used for the minimum energy pathway?MEP?calculations.Our studies show that the diffusion of single Pt atoms on WTe₂ monolayer has a strong anisotropy.Pt atoms prefer to diffuse along the W-W zigzag direction with the lowest energy barrier of 0.551 e V for pristine WTe₂ monolayer,0.463 e V for Ta-doped WTe₂ monolayer,and 0.508 e V for Re-doped WTe₂ monolayer.Our results show that both nand p-type dopants can enhance the preferred diffusion path of the Pt atom along the W-W zigzag direction as manifested by the modulated diffusion barriers.These findings are of great value and guidance in fabrication and modulation low dimensional transition metal nanostructures which can be anticipated to possess desirable functionalities for potential applications such as in nanocatalysis,nanosensors,and related areas.?2?Aiming at the strong anisotropy of the electronic structure of Td-WTe₂,we also studied the adsorption and growth of noble metal Au atoms on the surface of TdWTe₂ monolayer,and explored the adsorption of oxygen molecules on the surface of WTe₂ monolayer after growth of Au atom chains.Our calculations show that the most stable adsorption position of a single Au atom on the WTe₂ monolayer surface is along the lower Te atom chain direction.Then,we began to make Au atoms adsorb on the surface of the WTe₂ monolayer.By attempting to adsorb and growth at various positions,we found that the growth of Au atoms on the surface of WTe₂ is always along the lower Te atom chain direction and always grows into a novel Au atom chain of diatomic layer structure.By comparing the adsorption of Au atoms on the surface of WTe₂ in a dispersed with in a chain form,we found that the structure of Au atoms adsorbed on the surface of WTe₂ is more stable in a chain form.Then,we adsorbed oxygen molecules on the surface of WTe₂ which is adsorbed by Au atoms in a dispersed and in a chain form.The results show that the structure of adsorbed oxygen molecules on the surface of the WTe₂ after adsorbed by Au atoms is more stable and its energy is lower.The results of our study above provide a valuable guidance for leading to the realization of the fascinating properties of gold as a catalyst in the field of nanomaterials.