Heterointerface-Induced Charge Transfer Kinetics in Sputtered MoTe ₂ –MoS ₂ Nanocomposite for High-Performance Ambient NO ₂ Detection

The present research reports a nanostructured MoTe 2 –MoS 2 n-n heterojunction-based gas sensor developed on a silicon (Si) substrate, demonstrating room-temperature (RT, 30 °C) nitrogen dioxide (NO 2 ) sensing. A controlled and one-step magnetron co-sputtering approach is utilized to deposit MoTe 2 –MoS 2 nanocomposite thin film on a Si substrate, producing a uniform, dense, and porous nanoscale morphology. Herein, surface analysis and structural characterization of the MoTe 2 –MoS 2 /Si sensor reveal a rough and defect-rich morphology with abundant exposed edge sites, which significantly enhances the availability of active adsorption sites for effective gas sensing. The developed MoTe 2 –MoS 2 /Si heterostructured sensor delivers an exceptional sensor response of 74.4% with an ultrafast response/recovery time of 7.5/2 s toward 25 ppm of NO 2 at RT. Additionally, the present sensor showcases highly reproducible and consistent behavior over a wide range of NO 2 concentrations (1–60 ppm), along with remarkable selectivity against common potential interfering gases (H 2 S, NH 3, CO, H 2 ) and a low detection limit of 700 ppb. This study provides critical insights into NO 2 sensing induced by heterointerface band modulation and defect-assisted adsorption at the sensor’s surface, thereby providing a strong foundation for a reliable platform for high-performance NO 2 gas sensors based on the MoTe 2 –MoS 2 heterostructure.