Manufacturing of Zinc Oxide Nanoparticle-Functionalized Cellulose Nanofibrous Aerogel for Ultra-Fine Dust Filtration and Real-Time No₂ Detection

This study presents a multifunctional aerogel-based filter manufactured via freeze-casting process, designed for simultaneous ultrafine particulate matter (PM) filtration and real-time nitrogen dioxide (NO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) sensing. The filter comprises a cellulose nanofiber framework functionalized with zinc oxide nanoparticles, which form a conductive network and enable NO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> detection. By controlling the pore size and alignment within the aerogel, the filter achieves an average <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{PM}_{2.5}$</tex> removal efficiency of 90.2% with a low pressure drop of 24.6 Pa at 5.3 cm/s. Simultaneously, it exhibits a NO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> sensitivity of ~17.2%/ppm in air at room temperature. Unlike conventional filters, this aerogel integrates high-efficiency PM filtration with real-time gas sensing capabilities, offering a promising solution for both air pollution reduction and environmental monitoring.