Optothermally enhanced chemiresistive gas sensing via MoS2 integrated onto low-energy visible light-emitting diodes

Sensitive detection of nitrogen dioxide (NO 2 ) at room temperature is essential for energy-efficient environmental monitoring. Molybdenum disulfide (MoS 2 ) has emerged as a promising sensing material owing to its strong NO 2 adsorption capability; however, this same property also leads to incomplete recovery. Conventional approaches using external heating or global light illumination still suffer from high power consumption, inefficient photon transfer, and bulky auxiliary components. This study demonstrates a MoS 2 -based NO 2 sensor with localized, site-specific illumination, achieved by directly integrating the sensing layer onto the light-emitting surface of low-energy visible light-emitting diodes (LEDs). Illumination at ∼625 nm, corresponding to the excitonic absorption of MoS 2 , efficiently generates electron–hole pairs and enhances NO 2 sensitivity. With optimized operation, the sensor exhibits a high response of ∼146.21 % to 10 ppm NO 2 , which is more than twice that in the dark, achieving a sensitivity of ∼26.6 % ppm −1 for concentrations ranging from 1 ppm down to 0.1 ppm with negligible hysteresis. Moreover, heat generated from the LED junction is synergistically utilized with localized photoexcitation to improve recovery. This optothermally activated MoS 2 –LED platform offers a simple, scalable, and low-power approach for simultaneous environmental monitoring and lighting.