Fig. 5.

Multifunctional surgical face masks. a) Anti-influenza multilayer containing copper oxide face masks with corresponding SEM and XPS analysis (Borkow et al., 2010), b) reusable and recyclable graphene-coated superhydrophobic, self-cleaning and photothermal face masks (Zhong et al., 2020), c) reusable MoS₂-modified durable antibacterial and photothermal self-disinfection face masks (Kumar et al., 2021), d) reusable copper nanoparticles (CuNPs) antiviral and photo-thermal self-disinfecting face masks (Kumar et al., 2020), e) multifunctional face masks to protect people from PM pollutants and simultaneously achieve personal thermal comfort (Yang et al., 2017), f) skin temperature when covered with multifunctional face masks and two commercial face masks (Yang et al., 2017), g) filtration efficiency of a new KN95 mask, washed and dried mask, and recharged mask for 60 min. Decay of the efficiency of the recharged mask over the course of a day (Hossain et al., 2020), h) multifunctional mask by using BaTiO3@PU/PSA membrane achieved the high capture efficiency, low pressure drop, good mechanical property, sufficient flexibility, high thermal stability, favorable flame-retardancy as well as superior chemical resistance against acid and alkali (Yang et al., 2020).