High-efficiency air filter aerogel resembling blood cell with heterogeneous epitaxial growth of zeolitic imidazolate framework-8 anchored on tunicate cellulose nanofibers for integrated air cleaning

Abstract

Metal-organic frameworks (MOFs) possess highly ordered porous structures and photocatalytic capabilities, making them ideal for air cleaning and antibacterial applications. However, the crystallization kinetics of MOFs constrain their crystal structure, which limits their practical usage for air cleaning and other applications. Herein, we present a non-MOF template strategy to achieve heterogeneous epitaxial growth of zeolitic imidazolate framework-8 (ZIF-8) on cellulose extracted from tunicate. TEMPO-oxidation tunicate cellulose nanofibers (TOCNFs) have a high length-diameter ratio (>1000) and negatively charged carboxyl and hydroxyl groups that serve as suitable templates to promote heterogeneous nucleation of the ZIF-8 crystal, thereby resulting in the fabrication of a unique porous structure resembling blood cell. The ZIF-8@TOCNFs aerogel shows good porosity performance, achieving a maximum particulate matter (PM) removal efficiency of 95.80 % with a low pressure drop of 14 Pa at an air-flow velocity of 0.34 m/s. Compared to other works and commercial filters, ZIF-8@TOCNFs aerogel exhibits a higher quality factor (QF) of up to 0.197 Pa−1. Furthermore, ZIF-8@TOCNFs aerogel also demonstrates remarkable antibacterial and antiviral performance without UV photocatalysis. This unique design of ZIF-8@TOCNFs aerogel opens a new avenue for non-MOF template growth of MOF-on-MOF heterostructures and provides a novel strategy for preparing high-performance air filters with an integrated performance of low pressure drop, high removal efficiency and QF, great antibacterial and antiviral properties.