Sunlight-Driven Self-Cleaning Ultrafine Particulate Matter Filter with Antibacterial Activity

Abstract

Air pollution by particulate matter (PM) and airborne pathogens causes severe health problems in the human body. Presently, popular disposable air filters yield huge waste and have a fatal impact on the environment. Postuse cleaning of air filters also leads to secondary air and water pollution. Here, we report a sunlightdriven self-cleaning PM filter by coupling a full-solar-spectrum-active photocatalyst comprising up-conversion nanoparticles (UCNPs) decorated with semiconductor iron(III) oxide (UCNP@α-Fe 2 O 3 ) shells stabilized upon graphene functionalized borosilicate fibrous membrane (rGO-BF). While rGO-BF ensures high PM adsorption, UCNP@α-Fe 2 O 3 (NP) enables self-photodegradation of adsorbed PM under abundant sunlight and subsequent membrane regeneration, while preventing secondary air or water pollution. Rational surface chemistry and optimal microstructure enable our filters to remove >99% of PM 2.5 under deplorable air-quality conditions. Moreover, our filter shows excellent antibacterial activity toward E. coli and S. aureus, demonstrating its potential for practical utilization in face masks, air filtering devices, and protective medical wear. This work successfully suggests an intriguing design platform for self-sustainable zero-waste air filter membranes.

Sunlight-Driven Photothermally Boosted Photocatalytic Eradication of Superbugs Using a Plasmonic Gold Nanoparticle-Decorated WO3 Nanowire-Based Heterojunction

“…As we have discussed before, the photocatalytic efficiency of the WO 3 nanowire is significantly low, which is mainly due to the high degree of the recombination process between holes (h + ) and electron (e – ) pairs. − Since the recombination process between e – and h + restricts, WO 3 can be used in full capacity to produce ROS, which is the most important step for the photocatalytic process. − However, in the case of heterojunctions, due to the presence of GNPs, efficient separation of e – /h + pairs occurs as shown in Figure , which helps generate more ROS, which enhances the degradation. Equations – show the possible degradation mechanism for MB using the GNP-decorated WO 3 nanowire-based heterojunction-based photocatalyst. − , normalW normalO 3 ( N W ) + normalh ν → normalW normalO 3 ( N W ) [ normalh + false( normalV normalB false) ] + normalW normalO 3 ( N W ) ...…”

“…As reported in eqs –, due to the strong oxidizing abilities of holes, the h + helps form the hydroxy radicals ( • OH) by oxidizing water. − , The hydroxy radicals ( • OH) formed by the above reaction can combine with each other to form hydrogen peroxide. − , On the other hand, due to the strong reducing abilities of electrons, e – helps form the superoxide radical ( • O 2 – ) by reducing the oxygen molecule. − , In the next step, some superoxide radicals ( • O 2 – ) combine with holes and form singlet oxygen ( 1 O 2 ). − , All ROS formed by electron and holes [( • OH), ( • O 2 – ), and ( 1 O 2 )] are highly active oxidants that have capabilities to degrade MB. − , It is now well documented that due to the localized plasmon surface resonance, GNPs can absorb light and act as photothermal agents. During this process, GNPs have the capability to convert light energy into heat via nonradiation processes.…”

“…Since in the 21st century, superbug infection is one of the biggest battles in global health, the development of innovative antisuperbug agents that do not cause drug resistance is extremely important to save lives. − , Driven by the need of our society, in the current article, we report the design of a sunlight-driven photothermal–photocatalytic heterojunction using plasmonic gold nanoparticle (GNP)-decorated WO 3 nanowires for complete eradication of carbapenem-resistant Enterobacteriaceae Escherichia coli (CRE E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) superbugs as shown in Figure .…”

Wearable, Biocompatible, and Dual-Emission Ocular Multisensor Patch for Continuous Profiling of Fluoroquinolone Antibiotics in Tears

“…A high density of coordination polymers is absorbed on the surface of the glass fiber, indicating the ideal compatibility of nanosensor components with the paper-based substrate (Figure S16). Glass fiber-based filter paper has been widely employed as an important class of chemically and mechanically robust supporting matrices for personal protection against environmental pollutants or collisions, which takes the advantage of ideal resistance to chemical corrosions, good tensile strength, excellent dimensional stability, and high insulation ability. , In the regular healthcare use, the integrated eye patch exhibits satisfactory mechanical flexibility in the cases of bending, stretching, or torsion (Figure S17). Unlike the complexity in wearing a traditional contact-lens-based sensor, this proposed patch could be comfortably fitted under eyes without direct contact to the eye balls (Figure h).…”

Two-Dimensional Piezoelectric Nanofibrous Webs by Self-Polarized Assembly for High-Performance PM0.3 Filtration

“…Interception and capture are fundamental solutions to prevent the penetration of complex PMs. Furthermore, additional treatments such as inactivation, decontamination, and degradation are required for biohazardous microorganisms-containing aerosols. − According to the particle size, PMs can be categorized as PM 10 , PM 2.5 , and PM 0.3 , where PM 0.3 is the most penetrating particle size (∼300 nm). , The long-range propagation of PM 0.3 allows it to ignore the physical interception of the nasal mucosa and carry viruses or bacteria to cause serious infections, such as 2019 novel coronavirus (COVID-19), H1N1 influenza, and mycoplasma pneumonia. , Therefore, for the purpose of protecting public health, there is an urgent need to develop efficient air filtration materials against PM 0.3 .…”