Transition metal-doped ZrS₂ monolayer as potential gas sensor for CO₂, SO₂, and NO₂: density functional theory and non-equilibrium Green’s functions’ analysis

Abstract Density functional theory combined with the non-equilibrium Green’s function (NEGF) is used to systematically analyze the adsorption and sensing properties of a pristine ZrS 2 monolayer doped with transition metals (TMs) Ni, Pd, or Pt, for three target gases CO 2 , SO 2 , and NO 2 . Our findings reveal that the pristine ZrS 2 monolayer exhibits only a weak physical adsorption, whereas TM-doped monolayers show significantly enhanced sensing capabilities. The Ni–ZrS 2 monolayer increases the charge transfer for NO 2 by a factor of 6.75, while the Pd–ZrS 2 monolayer shows an eightfold improvement for SO 2 . Notably, the adsorption of NO 2 leads to substantial modifications in the band structure of the ZrS 2 monolayer, suggesting its use as a resistive NO 2 sensor. The Pd–ZrS 2 and Pt–ZrS 2 monolayers exhibit shorter recovery times at temperatures of 348 K and 398 K after adsorbing SO 2 and NO 2 , highlighting their suitability for repeated detection. Additionally, the transport properties of TM-ZrS 2 -based devices are analyzed by NEGF. For CO 2 , SO 2 , and NO 2 , sensitivities of up to 1.53, 4.60, and 2.01 are observed for the Pd–ZrS 2 , Pt–ZrS 2 , and Ni–ZrS 2 -based devices, respectively, under specific bias. This study demonstrates that TM-ZrS 2 -based devices can realize repetitive and sensitive detection of specific target gases at different temperatures and biases, revealing their potential applications.