Construction of Dual‐Channel Water Transport in Mesoporous Silica Low Humidity Sensors to Achieve High Sensitivity

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2023-11, Vol.19 (44), p.e2303251-n/a
• Main Authors: Ma, Zhiyan, Miao, Xiaoya, Song, Yaping, Yu, Yunlong, Wu, Ke, Liu, Sen, Fei, Teng, Zhang, Tong
• Format: Article
• Language: English
• Subjects: Adsorption; Channels; Chemical reactions; dual‐channel water transport; external surface grafting; Grafting; Humidity; intra‐pore grafting; Ionic liquids; low humidity sensors; Nanotechnology; Sensitivity; Sensors; Silicon dioxide; Surface chemistry; Water chemistry
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202303251

In this paper, strong hydrophilic poly(ionic liquid)s (PILs) are selectively grafted on different positions (mesoporous channels and outer surface) of mesoporous silica via thiol‐ene click chemical reaction. The purposes of selective grafting are on the one hand, to explore the differences of adsorption and transportation of water molecules in mesoporous channels and on the outer surface, and on the other hand, to combine the two approaches (intra‐pore grafting and external surface grafting) to reasonably design SiO2@PILs low humidity sensing film with synergetic function to achieve high sensitivity. The results of low relativehumidity （RH） sensing test show that the sensing performance of humidity sensor based on mesoporous silica grafted with PILs in the channels is better than that of humidity sensor based on mesoporous silica grafted with PILs on the outer surface. Compared with water molecules transport single channel, the construction of dual‐channel water transport significantly improves the sensitivity of the low humidity sensor, and the response of the sensor is up to 4112% in the range of 7–33% RH. Moreover, the existence of micropores and the formation of dual‐channel water transport affect the adsorption/desorption behaviors of the sensor under different humidity ranges, especially below 11% RH. The specific positions of mesoporous silica are selectively functionalized through thiol‐ene click reaction to enhance the water molecules adsorption capacity. A novel construction strategy of dual‐channel water transport is proposed to improve the sensitivity of humidity sensors, providing a promising method for designing low humidity sensing materials.