Issue 7, 2022

Hydrogel- and organohydrogel-based stretchable, ultrasensitive, transparent, room-temperature and real-time NO2 sensors and the mechanism

Abstract

Highly stretchable, sensitive and room-temperature nitrogen dioxide (NO2) sensors are fabricated by exploiting intrinsically stretchable, transparent and ion-conducting hydrogels and active metals as the novel transducing materials and electrodes, respectively. The NO2 sensor exhibits high sensitivity (60.02% ppm−1), ultralow theoretical limit of detection (6.8 ppb), excellent selectivity, linearity and reversibility at room temperature. Notably, the sensitivity can be maintained even under 50% tensile strain. For the first time, it's found that the metal electrodes significantly impact the sensing performance. Specifically, the sensitivity is boosted from 31.18 to 60.02% ppm−1 by replacing the anodic silver with copper–tin alloy. Importantly, by applying specially designed sensing tests, and microscopic and composition analyses, we have obtained the inherent NO2 sensing mechanism: the anodic metal tends to be oxidized and the NO2 molecules tend to react in the cathode–gel interface. The introduction of glycerol converts the hydrogel into the organohydrogel with remarkably enhanced anti-drying and anti-freezing capacities and toughness, which effectively improved the long-time stability of the sensors. Importantly, we execute sound/light alarms and a wireless smartphone alarm by utilizing a designed circuit board and applet. This work gives an incisive investigation for the preparation, performance improvement, mechanism and application of hydrogel-based NO2 sensors, promoting the evolution of hydrogel ionotronics.

Graphical abstract: Hydrogel- and organohydrogel-based stretchable, ultrasensitive, transparent, room-temperature and real-time NO2 sensors and the mechanism

Supplementary files

Article information

Article type
Communication
Submitted
06 mar 2022
Accepted
25 abr 2022
First published
25 abr 2022

Mater. Horiz., 2022,9, 1921-1934

Hydrogel- and organohydrogel-based stretchable, ultrasensitive, transparent, room-temperature and real-time NO2 sensors and the mechanism

Y. Wei, H. Wang, Q. Ding, Z. Wu, H. Zhang, K. Tao, X. Xie and J. Wu, Mater. Horiz., 2022, 9, 1921 DOI: 10.1039/D2MH00284A

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