Supplement Number 1

See the supplementary material for the • Experimental Section: (1) Materials and chemicals, (2) Materials characterizations, (3) Deposition of MoS2-MoSe2 nanoflakes and optimized sputtering parameters (Table S1), (4) NO2 sensing measurements, and (5) Gas sensing setup graphic presentation. • Energy band diagram for n-type MoS2 and n-type MoSe2. • Sensor response curves for pristine (a) MoS2/Si, and (b) MoSe2/Si towards 0.7 ppm NO2 at RT. • Sensor response of MoS2-MoSe2 nanocomposite (T2 sample) at different temperatures from RT to 100ºC towards 0.7 ppm NO2.