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The global COVID-19 pandemic has raised great public concern about the airborne transmission of viral pathogens. Virus-laden aerosols with small size could be suspended in the air for a long duration and remain infectious. Among a series of measures implemented to mitigate the airborne spread of infectious diseases, filtration by face masks, respirators, and air filters is a potent nonpharmacologic intervention. Compared with conventional air filtration media, nanofibrous membranes fabricated via electrospinning are promising candidates for controlling airborne viruses due to their desired characteristics, i.e., a reduced pore size (submicrometers to several micrometers), a larger specific surface area and porosity, and retained surface and volume charges. So far, a wide variety of electrospun nanofibrous membranes have been developed for aerosol filtration, and they have shown excellent filtration performance. However, current studies using electrospinning for controlling airborne viruses vary significantly in the practice of aerosol filtration tests, including setup configurations and operations. The discrepancy among various studies makes it difficult, if not impossible, to compare filtration performance. Therefore, there is a pressing need to establish a standardized protocol for evaluating the electrospun nanofibrous membranes’ performance for removing viral aerosols. In this perspective, we first reviewed the properties and performance of diverse filter media, including electrospun nanofibrous membranes, for removing viral aerosols. Next, aerosol filtration protocols for electrospun nanofibrous membranes were discussed with respect to the aerosol generation, filtration, collection, and detection. Thereafter, standardizing the aerosol filtration test system for electrospun nanofibrous membranes was proposed. In the end, the future advancement of electrospun nanofibrous membranes for enhanced air filtration was discussed. This perspective provides a comprehensive understanding of status and challenges of electrospinning for air filtration, and it sheds light on future nanomaterial and protocol development for controlling airborne viruses, preventing the spread of infectious diseases, and beyond. 

Graphitic carbon nitride (g-C 3 N 4 ) is an emerging visible-light-responsive photocatalyst that has been explored since 2009. This photocatalyst has highly tailorable structures and properties that enable potential utilization of a large portion of solar energy. This material is also synthesized from earth-abundant precursors, is chemically and thermally stable, and is biocompatible with no reported toxicity to date. The merits and pioneering performance evaluation of g-C 3 N 4 indicate that this photocatalyst holds promise for the degradation of persistent and emerging contaminants, including chemicals and pathogens, for sustainable water purification with reduced energy and chemical footprint. In this perspective, we propose and answer five questions that are most relevant to the development and application of g-C 3 N 4 for photocatalytic water purification, including both benefits and current barriers, from molecular-scale mechanistic understanding of g-C 3 N 4 properties and photocatalytic performance to industrial-scale photoreactor design for g-C 3 N 4 implementation in practice.