▎ 摘　　要

There is significant interest in developing new two-dimensional (2D) materials that can be utilized as stable and sensitive sensors for toxic gas detection. Here, we study the adsorptions of CO and NO molecules on the twin graphene (TG) decorated with transition metals (TM = Pd, Ti) (denoted as TG-TM-CO and TG-TM-NO) by first -principles calculations, and then determine the gas sensitive properties for CO or NO detection based on the TG -TM substrates. It is found that the TG-Pd substrate exhibits a preferable magnetic response to the NO adsorption compared to the CO adsorption. In contrast, the TG-Ti substrate is more sensitive to CO. We also explored the effects of electric field on the net magnetic moment and electronic structure for the TG-TM-gas systems. The net magnetic moments are almost impervious to the applied electric fields for the TG-TM substrates and the TG-TM -gas systems. With the presence of small electric fields, however, electrically-sensitive performance can be significantly enhanced for CO detection based on the TG-Ti substrate. Our results suggest that the TG-TM sub-strates (TM = Pd, Ti) have potential applications as a sensor to detect NO and CO by means of the handleable conversion of magnetic or electrical signal.