Photocatalytic inactivation of airborne bacteria onto g-C3N4/TiO2/Ni-polydopamine/Ni bifunctional coupling filter with non-size dependent capture effect

Most commercial air purifiers rely on dense fibrous filters for bioaerosols control, which filter the particulate matter size-dependently without bactericidal activity. Herein, the non-size-dependent bifunctional nickel foam filters (g-C3N4/TiO2(CT)/Ni-polydopamine(PDA)/Ni bifunctional filter) with two layers of coupling nickel foams deposited by CT and PDA, respectively, were developed. The bifunctional filter shows remarkable non-size dependent bacteria removal efficiency (93.5 %) and inactivation efficiency (∼70 %) within 20 min at high airflow (12.5 L min−1). The inactivation efficiency can be further increased to 99.99 % with prolong irradiation time and enhancement of light intensity. The non-size dependent capture effect of the CT/Ni-PDA/Ni provided by adhesive force and charge was verified. In addition, the assumption that reactive oxygen species (ROSs) could be transferred into air during bacteria inactivation was first proved by chemiluminescent. This pioneered study may provide new insights into the development of bifunctional filters for non-size dependent capture and photocatalytic inactivation of bacteria in bioaerosols.