Chemiresistive flexible gas sensor for NO2 sensing at room-temperature using in situ constructed Au@In2S3/In2O3 hybrid microflowers

The construction of a novel Au nanoparticles loaded In 2 S 3 /In 2 O 3 hybrid microflowers composite was conducted through a well-designed hydrothermal and partial oxidation method and used for NO 2 sensing at room-temperature (RT). The characterization data confirmed the hybrid structures and demonstrated that the ratio of adsorbed oxygen species on the surface increased after partial oxidation. The sensing performance of flexible gas sensors based on In 2 S 3 /In 2 O 3 , In 2 O 3 , Au x In 2 S 3 /In 2 O 3 (x = 0.5, 1 and 2 wt%) were tested and compared at RT. Heterostructure construction and Au NPs loading significantly improved the sensing properties at RT. Peculiarly, the response value of 1 wt% Au NPs loaded In 2 S 3 /In 2 O 3 (Au 1 In 2 S 3 /In 2 O 3 ) sensor for 100 ppm NO 2 at RT was 20.7, which was 9.2 times higher than that of In 2 O 3 sensor. Meanwhile, it also possessed excellent selectivity, fast response/recovery time (12/27 s), good repeatability, long-term and mechanical stability. The outstanding sensing performance for NO 2 at RT mainly associated to the heterojunction between In 2 S 3 and In 2 O 3 and the catalytic effect of Au NPs. Finally, density functional theory (DFT) was used to calculate and analyze the gas adsorption and charger transfer, which related to the enhanced sensing performance.