Ab initiostudy of bilateral doping within theMoS2-NbS2system

Abstract

We present a systematic study on the stability and the structural and electronic properties of mixed molybdenum-niobium disulphides. Using density functional theory we investigate bilateral doping with up to 25 % of MoS2 (NbS2) by Nb (Mo) atoms, focusing on the precise arrangement of dopants within the host lattices. We find that over the whole range of considered concentrations, Nb doping of MoS2 occurs through a substitutional mechanism. For Mo in NbS2 both interstitial and substitutional doping can co-exist, depending upon the particular synthesis conditions. The analysis of the structural and electronic modifications of the perfect bulk systems due to the doping is presented. We show that substitutional Nb atoms introduce electron holes to the MoS2, leading to a semiconductor-metal transition. On the other hand, the Mo doping of Nb2, does not alter the metallic behavior of the initial system. The results of the present study are compared with available experimental data on mixed MoS2-NbS2 (bulk and nanoparticles).

On the Stability and Electronic Structure of Transition-Metal Dichalcogenide Monolayer Alloys Mo1−xXxS2−ySey with X = W, Nb

“…The Nb atom has one electron less than the Mo atom in the valence shell; therefore, an introduction of a single Nb results in an electron hole, which acts as an acceptor impurity. Similar results were obtained from DFTB calculations by Ivanovskaya et al [19]. …”

“…These energies, however, become nearly zero for Nb concentration above 15 at%, as at this point, the dopants start to cluster inside the host material. Ivanovskaya et al [17,19] have also reported clustering of Nb atoms in nanotubes and monolayers; however, they obtained negative formation energies from the density functional-based tight-binding (DFTB) calculations.…”

Doping against the Native Propensity of MoS2: Degenerate Hole Doping by Cation Substitution

“…25 Moreover, MoS 2 and NbS 2 share the identical 2H crystal structure, with similar lattice parameters, a = 3.16 and 3.32 Å and c = 12.29 and 11.94 Å for MoS 2 and NbS 2 , respectively. 26 The covalent radius (Mo = 130 pm and Nb = 134 pm) 27 and oxidation states of Mo and Nb in the 2H-polytype lattice are nearly identical. Indeed, fullerene-like Mo x Nb 1−x S 2 nanoparticles 28 and polycrystalline thin-films 29 have been reported, but unambiguous p-type conduction and direct evidence of the substitutionality of doping have not been demonstrated in single-crystal MoS 2 .…”

Ag and Au atoms intercalated in bilayer heterostructures of transition metal dichalcogenides and graphene

“…36,37 The electrical conductivity of MoS 2 can be altered by substitutional doping. 38,39 Furthermore, decoration of the surfaces of few layer TMDs by metal nanoparticles such as Au, Ag, and Pt may provide p-and n-type doping. [40][41][42][43] The metal-atom adsorbed TMDs find their application in various areas including energy storage, 44 photonics, 45,46 biosensing, 47 and catalysis.…”