2D/2D SnS2/SnSe2 van der Waals heterostructure for highly sensitive room-temperature NO2 sensor: Key role of interface contact

•Two sets of 2D/2D SnS2/SnSe2 vdW heterostructures are fabricated for room-temperature high-sensitive NO2 sensors.•The key role of the distance of interface contact in vdW heterostructure is revealed by DFT calculation and XPS analysis.•Increasing heterojunction and improving interface contact enhance the sensing properties of SnS2/SnSe2 vdW heterostructure.•High response value and sensitivity for NO2 gas are achieved in 2D/2D vdW heterostructure at room temperature.