Face masks will be used to prevent pandemic recurrence and outbreaks of mutant SARS-CoV-2 strains until mass immunity is confirmed. The polypropylene (PP) filter is a representative disposable mask material that traps virus-containing bioaerosols, preventing secondary transmission. In this study, a copper thin film (20 nm) was deposited via vacuum coating on a spunbond PP filter surrounding a KF94 face mask to provide additional protection and lower the risk of secondary transmission. Film adhesion was improved using oxygen ion beam pretreatment, resulting in cuprous oxide formation on the PP fiber without structural deformation. The copper-coated mask exhibited filtration efficiencies of 95.1 ± 1.32% and 91.6 ± 0.83% for NaCl and paraffin oil particles, respectively. SARS-CoV-2 inactivation was evaluated by transferring virus-containing media onto the copper-coated PP filters and subsequently adding Vero cells. Infection was verified using real-time polymerase chain reaction and immunochemical staining. Vero cells added after contact with the copper-coated mask did not express the RNA-dependent RNA polymerase and envelope genes of SARS-CoV-2. The SARS-CoV-2 nucleocapsid immunofluorescence results indicated a reduction in the amount of virus of more than 75%. Therefore, copper-coated antiviral PP filters could be key materials in personal protective equipment, as well as in air-conditioning systems.

Solvent vapor annealing (SVA) is an effective post-treatment process to improve the quality of crystals and grains in metal halide perovskite films. Whereas SVA has been successfully adopted for the fabrication of perovskite films via the conventional two-step method, its adaptation to the simple single-step perovskite film deposition method has been limited because of the rapid transition of the precursor to the perovskite structure. In the present study, we demonstrate highly efficient and stable single-step-based inverted perovskite solar cells fabricated with perovskite films prepared using dimethyl sulfoxide (DMSO) and water as a combined solvent in SVA treatment. The treatment with DMSO alone resulted in the growth of large grains (∼900 nm) in the lateral direction at the surface region; however, voids and defects were observed in the vertical direction at the bottom interfacial region of the CH₃NH₃PbI₃ layer, which resulted in poor device properties. Interestingly, the combined DMSO–water induced vertical growth of almost single grains and the healing effect of water improved the grain quality. As a result, we fabricated co-SVA CH₃NH₃PbI₃ devices with a power conversion efficiency (PCE) of 19.52%. This PCE, which is much higher than that of pristine devices, was attributed to reduced nonradiative recombination. In addition, co-SVA solar cells displayed remarkable stability and their universality in various types of perovskite materials was demonstrated. We anticipate that our proposed process and mechanism will be widely used in the future development of perovskite-based devices.

A sponge-based surface-enhanced Raman scattering (SERS) sensor composed of silver nanowires (AgNWs) coated with hydrophobic hexagonal boron nitride (hBN) was prepared for the simultaneous separation and detection of organic pollutants. AgNWs adhered on a melamine-sponge surface formed a high density of hotspots for Raman signal enhancement, and hydrophobic hBN coated on AgNWs functioned as an absorbent for the separation of organic pollutants from water via hydrophobic and π–π interactions. Due to the advantages of Raman spectroscopy, which provides an intrinsic molecular Raman signal, typical organic pollutants such as benzene, toluene, ethylbenzene, and xylene (BTEX) were identified by a portable Raman spectrometer with a label-free method after separation through the developed sensor. Further, binary and ternary mixtures of BTEX were also recognized by comparing the Raman spectrum of each component in the mixtures and easily classified by principal component analysis (PCA). Finally, absorbent capacity, reusability tests, and application to environmental water using the developed hBN/AgNWs/sponge samples showed the excellent organic pollutant separation properties as a hydrophobic sponge and the cost effective utilization of the developed sensor for molecular detection. The developed hBN/AgNWs/sponge sensor is expected to be applicable for various on-site and label-free separations and identifications of organic substances, such as environmental and biomedical monitoring.