Electronic Modulation\nof Doped MoS<sub>2</sub> Nanosheets\nfor Improved CO<sub>2</sub> Sensing and Capture

Transition-metal dichalcogenides (TMDs) are widely used\nin the\ngas sensing field, owing to their high surface-to-volume ratio enabled\nby the two-dimensional (2D) structure, adjustable band gap, and high\nelectron transfer. However, it is challenging for TMD materials to\nrealize superior CO<sub>2</sub> sensing, due to their weak CO<sub>2</sub> adsorption capacity. Herein, we predict through density functional\ntheory (DFT) calculations that rare earth metal doping is an effective\nstrategy to boost the CO<sub>2</sub> sensing capability of TMDs. As\na proof-of-concept, we investigate and find that the introduction\nof rare earth metal atoms (La, Ce, Pr, or Nd) can induce lattice strain\nand modulate the electronic properties of MoS<sub>2</sub>. When negative\ncharges are injected in rare earth metal doped MoS<sub>2</sub> (R-MoS<sub>2</sub>), the 5d or 4f orbital of the rare earth metal atom in R-MoS<sub>2</sub> can produce a stronger orbital hybridization with 2p orbitals\nof C and O in CO<sub>2</sub>. Therefore, the CO<sub>2</sub> adsorption\nis significantly enhanced and the charge transfer is facilitated for\nnegatively charged R-MoS<sub>2</sub>. Moreover, negatively charged\nR-MoS<sub>2</sub> exhibits an excellent CO<sub>2</sub> selectivity.\nOur results indicate that the rare earth metal doping and electronic\nmodulation in 2D materials may provide a new pathway for CO<sub>2</sub> sensing and capture.