背景:气体的吸附(CO,CO2,NH3)由金属(Au,Ag,通过密度泛函理论研究了Cu)掺杂的单层WS2。金属原子的掺杂使WS2表现为n型半导体。CO的最终吸附位点,CO2和NH3靠近掺杂金属的原子位点。CO和NH3气体在Cu/WS2,Ag/WS2和Au/WS2上的吸附受化学吸附支配。掺杂的金属原子增强了衬底与气体分子轨道的杂化,这有助于电荷转移并增强气体与材料表面的吸附。CO和NH3在Cu/WS2和Ag/WS2上的吸附允许在加热后的短时间内有利的解吸。单层Cu/WS2被证明具有用作CO的可靠可回收传感器的潜力。该工作为开发基于WS2的高性能气体传感器提供了理论依据。
方法:在本文中,吸附能,电子结构,电荷转移,和CO的恢复时间,基于密度泛函理论的CASTEP代码研究了掺杂系统中的CO2和NH3。使用的交换相关函数是Perdew-Burke-Ernzerhof(PBE)广义梯度近似(GGA)。TS(Tkatchenko-Scheffler)色散校正方法用于涉及范德华相互作用对所有吸附系统吸附能的影响。选择超软伪势,并将平面波截止能量设置为500eV。由Monkhorst封装方案生成的k点网格用于执行布里渊区的数值积分,并使用5×5×1k点网格。总能量收敛的公差,最大离子力,离子置换,应力分量为1.0×10-5eV/atom,0.03eV/贝达,0.001贝达,和0.05GPa,分别。
BACKGROUND: The adsorptions of gas (CO, CO2, NH3) by metal (Au, Ag, Cu)-doped single layer WS2 are studied by density functional theory. The doping of metal atoms makes WS2 behave as n-type semiconductors. The final adsorption sites for CO, CO2, and NH3 are close to the atomic sites of the doped metal. The adsorptions of CO and NH3 gases on Cu/WS2, Ag/WS2, and Au/WS2 are dominated by chemisorption. The doped metal atoms enhance the hybridization of the substrate with the gas molecular orbitals, which contributes to the charge transfer and enhances the adsorption of the gas with the material surface. The adsorptions of CO and NH3 on Cu/WS2 and Ag/WS2 allow favorable desorption in a short time after heating. The single-layer Cu/WS2 is proved to have the potential to be used as a reliable recyclable sensor for CO. This work provides a theoretical basis for developing high-performance WS2-based gas sensors.
METHODS: In this paper, the adsorption energy, electronic structure, charge transfer, and recovery time of CO, CO2, and NH3 in the doped system have been investigated based on the CASTEP code of density functional theory. The exchange correlation function used is the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). The TS (Tkatchenko-Scheffler) dispersion correction method was used to involve the effects of van der Waals interaction on the adsorption energies for all adsorption system. The ultrasoft pseudopotentials are chosen and the plane-wave cut-off energies are set to 500 eV. The k-point mesh generated by the Monkhorst package scheme is used to perform the numerical integration of the Brillouin zone and 5 × 5 × 1 k-point grid is used. The tolerances of total energy convergence, maximum ionic force, ionic displacement, and stress component are 1.0 × 10-5 eV/atom, 0.03 eV/Å, 0.001 Å, and 0.05 GPa, respectively.