Tailoring the sensing capability of 2H-MoSe2 via 3d transition metal decoration

To gain a first insight into the application of 3d transition metal (TM) decorated MoSe2 (TM-MoSe2) monolayer as chemiresistive sensors, the first-principles calculation was used to investigate the adsorption performance of four dissolved gases in transformer oil on MoSe2 monolayer. The stability of the TM-MoSe2 monolayer was firstly considered, and then the adsorption energy, electronic properties, and recover time were calculated to comprehensively analyze the adsorption performance of TMs-MoSe2 systems. Only the Co and Ni elements can be stably decorated on the MoSe2 monolayer surface. The calculated gas adsorption performance shows that the TMs with high d-band center location, can dramatically enhance the adsorption energy of MoSe2 monolayer towards four gas molecules. Such strong enhanced adsorption performance is mainly derived from the strong orbital hybridization between the TMs and gas molecules, forming the typical bonding states in the valence band and anti-bonding states in conduction bands. Additionally, Co-MoSe2 and Ni-MoSe2 monolayers would be promising candidates for H2 and C2H2 detectors, respectively. This research can deepen the insights into the 3d transition metal decorating effect on pristine MoSe2 monolayer and enrich the potential pathways to design MoSe2-based gas sensors with high gas-sensitive properties in oil-immersed transformers.