STRUCTURAL AND ELECTRONIC PROPERTIES OF Pd AND Au MONOLAYERS ADSORBED ON MoS2: A COMPARATIVE STUDY FROM DFT CALCULATIONS

The morphology, stability and electronic properties of Pd and Au monolayers supported by MoS2 substrate have been investigated by using the fit principles calculations based on periodic density functional theory (DFT). The results demonstrated that the most stable site is top of Mo top of S (T-S) for the adsorption of Pd and Au monolayers on MoS2. We found that Pd/MoS2 with lower adsorption energy of -0.54 eV is energetically more stable than Au/MoS2. Due to the emergence of impurities state in the bandgap of MoS2, Pd/MoS2 and Au/MoS2 display metallic character upon coating of metal monolayers. We demonstrated that the Pd monolayer strongly hybrids with underlying Mo and S around the Fermi level, which is achieved by the intermediate Pd-S-Mo hybridized chains. On the contrary, intensity of impurities states around the fermi level is much weaker for Au/MoS2, which can be explained by weak hybridizations between sp state of Au and 4d state of nearest neighboring Mo. The calculated results demonstrated that work functions are markedly modulated to 4.99 and 6.23 eV after coating of Pd and Au monolayer, respectively, which can be qualitatively explained by the fact that Pd (as accepter) received charge from the MoS2 host, while Au donated charge to the host. These findings promise potential applications in the fields of nanoelectronics in future, such as it's helpful to choose suitable electrode materials for MoS2-based nanodevices.