Cavitation-Tailored Cellulosic Triboelectric Aerogels via Dynamic Freeze-Casting for Stable Formaldehyde Monitoring

Cellulose aerogels are promising for self-powered formaldehyde sensing due to their three-dimensional network and intrinsic tribopositivity. However, uncontrollable pore diameter and distribution lead to electrical signal fluctuations and hinder formaldehyde diffusion within the aerogel, compromising the sensitivity and stability of the sensor. Herein, a dynamic freeze-casting strategy based on the cavitation effect is proposed to prepare triboelectric aerogels with tunable pore diameters and enhanced sensitivity. The cavitation effect refines the ice template, improving uniformity and spatial distribution while facilitating the homogeneous self-assembly of aminated cellulose, thereby reducing the pore diameter distribution by 33%. The tailored pore structure increases the induced charge density and provides more reaction sites for formaldehyde. Consequently, the optimized sensor exhibits a 224.7% increase in open-circuit voltage and a 463.7% increase in power density, enabling sensitive formaldehyde detection. This study provides a new path for structural control of cellulose aerogels, advancing gas monitoring technologies for environmental applications.