“…Various techniques have been attempted to improve the self-sterilization and antimicrobial properties of the nonwoven fabrics of face masks ( Seidi et al, 2021 ), such as coating with salt ( Quan et al, 2017 , Rubino et al, 2020 ), metal nanoparticles ( Kumar et al, 2020a , Kumar et al, 2020b , Kumar et al, 2020a , Kumar et al, 2020b , Zhong et al, 2020a , Zhong et al, 2020b , Zhong et al, 2020c ), and the incorporation of graphene ( Chua et al, 2020 , Huang et al, 2020 , Shan et al, 2020 , Zhong et al, 2020a , Zhong et al, 2020b , Zhong et al, 2020c ) and photosensitizers in the mask layers ( Horvath et al, 2020 , Monge et al, 2020 , Tang et al, 2020 ). Despite noteworthy progress in last year in the construction of functional nonwoven fabrics of face masks, enormous challenges still remain for practical applications of these functional-modified face masks: (i) most of the modifications have been performed on non-biodegradable PP-based nonwoven fabric which has already created significant environmental concerns after disposal ( Chen et al, 2021 , Kwak and An, 2021a , Kwak and An, 2021b , Morgana et al, 2021 ); (ii) most of these functional nonwoven fabrics require an external stimulus (including light, voltage, and pressure) to trigger the functions which practically limits the applications.…”