Multifunctional 2D g-CN/MoS vdW Heterostructure-Based Nanodevices: Spin Filtering and Gas Sensing Properties.

Two-dimensional (2D) magnetic materials are the key to the development of the new generation in spintronics technology and engineering multifunctional devices. Herein, the electronic, spin-resolved transmission, and gas sensing properties of the 2D g-CN/MoS van der Waals (vdW) heterostructure have been investigated by using density functional theory with non-equilibrium Green's function method. First, the g-CN/MoS vdW heterostructure demonstrates ferromagnetic half-metallicity and superior adsorption capacity for gas molecules. The spin-dependent electronic transport of the g-CN/MoS-based nanodevice is obviously regulated by parallel or anti-parallel spin configuration in electrodes, leading to perfect single-spin conduction behavior with a nearly 100% spin filtering efficiency, a negative differential resistance effect, and other interesting electrical transport phenomena. Moreover, g-CN/MoS exhibits directional dependency and strong transport anisotropic behavior under bias windows, indicating that the electric current propagates more easily through the vertical direction than the horizontal direction. The physical mechanisms are revealed and analyzed by presenting the bias-dependent transmission spectra in combination with the projected local device density of states. Finally, the g-CN/MoS-based gas sensor is more sensitive to CO, NO, NO, and NH molecules with the chemisorption type. The strong chemical adsorption leads to the formation of electrons on the local scattering center and ultimately affects the transport properties, resulting in the maximum gas sensitivity reaching 6.45 for NO at the bias of 0.8 V. This work not only reveals that the g-CN/MoS vdW heterostructure with high anisotropy, perfect spin filtering, and outstanding gas sensitivity is a promising 2D material but also provides an insight into the further application in futuristic electronic nanodevices.