Robust three-dimensional bioinspired honeycomb structured ultra-elastic aerogels for high-temperature cascade filtration applications

High-temperature particulate matter (PM), commonly produced by daily power generation, industrial smokestacks, and vehicle exhaust emissions, causes a significant risk to public health and environmental sustainability. The current strategy for solving these problems is to utilize adsorption filtration technology. In this work, we successfully constructed a bioinspired honeycomb structured aerogel with nano/micron fiber-reinforced polyimide gradient by using two strategies of fiber-reinforced filler and stepwise directional freezing technique. It overcomes the high shrinkage of polyimide aerogel and exhibits super elastic recovery performance without damage after 100 compression cycles at 50% strain, as well as high flame-retardancy and low thermal conductivity (32.14 mW m−1 K−1). Meanwhile, it shows excellent air filtration efficiency of about 97% and pressure drop of about 90 Pa after 50 cycles, as well as an excellent oil/organic solvent absorption performance and recoverability. In principle, the gradient structure with gradual change shows the "medium pore-small pore" cascade interception effect in the direction of airflow velocity propagation, which successfully achieves the selective and precise interception of polydisperse particles and the stratified accumulation of particles. It further significantly extends the filter service life and provides new insights into the upgrade of new high-temperature filters with significant research implications.