Synergistic cellulose–MoS₂ composites for high–performance humidity sensing

To overcome the suboptimal performance of paper–based humidity sensors, sensing composite materials were developed through the aqueous–mechanical defibration of everyday office paper into paper–derived cellulose fibers (PDCFs), followed by integration with molybdenum disulfide (MoS₂) microspheres. This straightforward yet effective strategy affords significant advantages for enhancing sensing capabilities. Specifically, the defibration process increases available adsorption sites by exposing hydrophilic groups while simultaneously generating more porosity for accelerated water vapor diffusion. Furthermore, utilization of the PDCFs suspension facilitates uniform dispersion of MoS₂ microspheres throughout the cellulose matrix, thereby harnessing synergistic effects from both components to improve sensing performance. Additionally, the aqueous composite's drop–casting compatibility enables utilization of microscale interdigitated electrodes (IDEs) spacing to enhance sensitivity. The resulting PDCFs–MoS₂ film sensor demonstrates exceptional characteristics, including a high response value (4167.8), a broad detection range (0–97 % RH), rapid response and recovery time (1.0 and 22.6 s, respectively), low hysteresis (3.8 %), good repeatability, and long–term stability. The sensor's practical utility was validated via human respiration monitoring and non–contact switching. This work establishes a viable pathway for transforming office paper into high–performance humidity–sensing materials.