N-doped three-dimensional needle-like CoS2 bridge connection Co3O4 core-shell structure as high-efficiency room temperature NO2 gas sensor.

The N-doped three-dimensional (3D) needle bridge connection core-shell structure N-CoS2@Co3O4 synthesized in this work was prepared by simple hydrothermal and high-temperature vulcanization methods. The optimized N-CoS2@Co3O4-2 composite response to NO2 is 62.3-100 ppm, a response time of 1.3 s, the recovery time of 17.98 s, the detection limit of 5 ppb and stability of as long as 10 weeks at room temperature (RT). Its excellent NO2 sensing performance is attributed to the unique porous and bridge connection core-shell structure of the N-CoS2@Co3O4-2 with high specific surface area, interconnected internal channels, abundant exposed S edge active sites, and high catalytic performance promoted by N-doping. This simple manufacturing method of high-performance sensing materials paves the way for the design of N-doped bridge connection core-shell structures.

Edge-exposed MoS2 nanospheres assembled with SnS2 nanosheet to boost NO2 gas sensing at room temperature.

SnS2 nanosheets (NSs) have become an ideal candidate for high performance gas sensors due to their unique sensing properties. However, the restacking and aggregation in the process of sensor manufacturing have great influence on the gas sensing performance. In this study, we synthesized a novel heterojunction of the flower-like porous SnS2 NSs with edge exposed MoS2 nanospheres via a facile hydrothermal method and sensitive response has achieved at room temperature (27℃). After functionalization, the SMS-Ⅱ showed excellent response (Ra/Rg = 25.9-100 ppm NO2), which is 22.3 times higher than that of the pristine SnS2 NSs. The sensor also has the characteristics of short response time of 2 s, excellent base line recovery (28.2 s), long-term stability and reliability within 16 weeks, good selectivity and low detection concentration of only 50 ppb. The p-n heterojunction formed between the edge-exposed spherical MoS2 and the 3D flower-like SnS2 NSs has a synergistic effect, providing a highly active sites for the adsorption of NO2 gas, which greatly enhance the sensitivity of the sensor. Simple fabrication and excellent gas sensing performance of the SnS2/MoS2 heterostructure nanomaterials (NMs) will highly effective for commercial gas sensing application.