Highly Selective Room-Temperature Blue LED-Enhanced NO2 Gas Sensors Based on ZnO-MoS2-TiO2 Heterostructures.

This study presents the fabrication and characterization of highly selective, room-temperature gas sensors based on ternary zinc oxide-molybdenum disulfide-titanium dioxide (ZnO-MoS2-TiO2) nanoheterostructures. Integrating two-dimensional (2D) MoS2 with oxide nano materials synergistically combines their unique properties, significantly enhancing gas sensing performance. Comprehensive structural and chemical analyses, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR), confirmed the successful synthesis and composition of the ternary nanoheterostructures. The sensors demonstrated excellent selectivity in detecting low concentrations of nitrogen dioxide (NO2) among target gases such as ammonia (NH3), methane (CH4), and carbon dioxide (CO2) at room temperature, achieving up to 58% sensitivity at 4 ppm and 6% at 0.1 ppm for NO2. The prototypes demonstrated outstanding selectivity and a short response time of approximately 0.51 min. The impact of light-assisted enhancement was examined under 1 mW/cm2 weak ultraviolet (UV), blue, yellow, and red light-emitting diode (LED) illuminations, with the blue LED proving to deliver the highest sensor responsiveness. These results position ternary ZnO-MoS2-TiO2 nanoheterostructures as highly sensitive and selective room-temperature NO2 gas sensors that are suitable for applications in environmental monitoring, public health, and industrial processes.