Band structure engineering of monolayer MoS2: a charge compensated codoping strategy

Abstract

The monolayer MoS₂, possessing an advantage over graphene in that it exhibits a band gap whose magnitude is appropriate for solar applications, has attracted increasing attention because of its possible use as a photocatalyst. Herein, we propose a codoping strategy to tune the band structure of monolayer MoS₂ aimed at enhancing its photocatalytic activity using first-principles calculation. The monodoping (halogen element, Nd) introduces impurity states in the gap, thus decreasing the photocatalytic activity of MoS₂. Interestingly, the Nb_MoF_S codoping reduces the energy cost of doping as a consequence of the charge compensation between the niobium (p-dopant) and the fluorine (n-dopant) impurities, which eliminates the isolated levels (induced by monodopant) in the band gap. Most importantly, the Nb_MoF_S codoped MoS₂ has more active sites for photocatalysis. These results show the proposed Nb_MoF_S codoped monolayer MoS₂ is a promising photocatalyst or photosensitizer for visible light in the heterogeneous semiconductor systems.