Flexible Humidity Sensor Based on a Graphene Oxide–Carbon Nanotube-Modified Co<sub>3</sub>O<sub>4</sub> Nanoparticle-Embedded Laser-Induced Graphene Electrode
Lei Li, Jiaming Zhang, Yang Song, Ronghui Dan, Xiaojuan Xia, Jiang Zhao, Rongqing Xu
Abstract
To meet evolving humidity monitoring needs, the development of flexible, high-performance humidity sensors is crucial. This study introduces an innovative flexible humidity sensor using a single-step laser scribing technique to fabricate a flexible in situ Co 3 O 4 nanoparticle-embedded laser-induced graphene (Co 3 O 4 –LIG) composite electrode. Compared to conventional LIG electrodes, the Co 3 O 4 –LIG electrode exhibits improved conductivity and hydrophilicity, enhancing charge transfer and water molecule affinity. The unique two-dimensional structure and exceptional water permeability of graphene oxide (GO) combine with the rapid water response and high specific surface area of carboxylated multiwalled carbon nanotubes (MWCNTs), thereby assuming a crucial function in the modification and optimization of the performance of humidity sensors. Through the application of a homogenously blended aqueous solution comprising GO and MWCNTs in precise proportions onto the Co 3 O 4 –LIG composite electrode, an excellent humidity-responsive layer is established, culminating in the realization of a cutting-edge GO–MWCNTs@Co 3 O 4 –LIG flexible humidity sensor. Noteworthy attributes of this sensor include a heightened sensitivity [959.1% (Δ R / R 0 )], rapid response and recovery times (within 5 and 26 s, respectively), and a noteworthy linearity ( R 2 = 0.994) across a relative humidity range of 14 to 95%. The findings presented herein offer valuable insights and a practical blueprint for the design and production of flexible humidity sensors.