Room-temperature response of Ni3(HITP)2 nanosheets co-functionalized with Au NPs and WS2 QDs based flexible chemiresistive NO2 gas sensor

Electrically conductive metal-organic frameworks (EC-MOFs) exhibit significant potential application as sensing materials for chemical resistance gas sensors. Herein, we developed a flexible gas sensor based on Ni 3 (HITP) 2 nanosheets co-functionalized with noble metal nanoparticles (NPs) and WS 2 quantum dots (QDs) for NO 2 detection at room temperature. The gas sensing performance was regulated by optimizing the metal species and loading ratios of WS 2 QDs. The measured results revealed that Au NPs and 2 mol% WS 2 achieved the most effective enhancement for NO 2 sensing performance. Therefore, Au NPs was selected to optimize WS 2 -2/Ni 3 (HITP) 2 sensor for further improving the sensing properties. A unique hierarchical structure based on gas sensor (Au 3 @WS 2 -2/Ni 3 (HITP) 2 sensor) enables high response (14.73 % to 5 ppm NO 2 ), rapid response/recovery time (97 s/110 s), good selectivity, anti-humidity, repeatability, long-term stability as well as flexibility at room temperature. Furthermore, density functional theory (DFT) and band theory were employed to comprehend adsorption energies and the electronic structures at atomic scale, elucidating the intrinsic correlation between NO 2 adsorption behavior and Ni 3 (HITP) 2 surface and the sensitization mechanism of heterostructures. These findings provide novel insights for designing high-performance NO 2 gas sensors worked at room temperature and guidance for EC-MOFs sensing mechanism.