  Using density functional theory combined with nonequilibrium Green's function
method, the transport properties of borophene-based nano gas sensors with gold
electrodes are calculated, and comprehensive understandings regarding the
effects of gas molecules, MoS$_2$ substrate and gold electrodes to the
transport properties of borophene are made. Results show that borophene-based
sensors can be used to detect and distinguish CO, NO, NO$_2$ and NH$_3$ gas
molecules, MoS$_2$ substrate leads to a non-linear behavior on the
current-voltage characteristic, and gold electrodes provide charges to
borophene and form a potential barrier, which reduced the current values
compared to the current of the systems without gold electrodes. Our studies not
only provide useful information on the computationally design of
borophene-based gas sensors, but also help understand the transport behaviors
and underlying physics of 2D metallic materials with metal electrodes.
