Reusable and Recyclable Graphene Masks with Outstanding Superhydrophobic and Photothermal Performances

Abstract

The 2019 coronavirus outbreak (COVID-19) is affecting over 210 countries and territories, and it is spreading mainly by respiratory droplets. The use of disposable surgical masks is common for patients, doctors, and even the general public in highly risky areas. However, the current surgical masks cannot self-sterilize in order to reuse or be recycled for other applications. The resulting high economic and environmental costs are further damaging societies worldwide. Herein, we reported a unique method for functionalizing commercially available surgical masks with outstanding self-cleaning and photothermal properties. A dual-mode laser-induced forward transfer method was developed for depositing few-layer graphene onto low-melting temperature nonwoven masks. Superhydrophobic states were observed on the treated masks’ surfaces, which can cause the incoming aqueous droplets to bounce off. Under sunlight illumination, the surface temperature of the functional mask can quickly increase to over 80 °C, making the masks reusable after sunlight sterilization. In addition, this graphene-coated mask can be recycled directly for use in solar-driven desalination with outstanding salt-rejection performance for long-term use. These roll-to-roll production-line-compatible masks can provide us with better protection against this severe virus. The environment can also benefit from the direct recycling of these masks, which can be used for desalinating seawater.

Face Masks in the New COVID-19 Normal: Materials, Testing, and Perspectives

“…In addition to their antimicrobial activities, functionalized graphene and graphene-based composites have been reported to confer superhydrophobicity onto material surfaces. Very recently, Zhong et al [232] established the deposition of few-layer graphene onto commercial nonwoven masks via dual-mode laser-induced forward transfer. The graphene-deposited mask exhibited outstanding superhydrophobic and photothermal performance.…”

A materials-science perspective on tackling COVID-19

“…To address this challenge, fibres, such as washable polypropylene fibres coated with assembled metal-organic frameworks 111 or thermally stable electrospun polyimide/zeolitic imidazolate framework-8 nanofibres 112 , could be applied that tolerate heat, ultraviolet irradiation 113 and hydrogen-peroxide treatment. In addition, a self-cleaning capability could be implemented by changing the surface chemistry of the material or by coating materials with photothermal materials 32,109 or hydrophobic membranes 31 to capture, kill and release the virus; for example, likewise, using filters composed of metal-organic frameworks with photodynamic ability 109 or graphene with photothermal ability 32 . Functional nanofibres, for example, fibres modified with amino-functionalized silica particles 114 or nanodecoys 66 capable of capturing viruses through charge interactions or by active recognition, could also be used for masks and manufactured by nanospinning 115 or 3D printing 116,117 .…”

“…Nanoparticles can also be modified with elements of host-cell membranes to inhibit viral entry 64,66 ; for example, nanomaterials can be decorated with host-cell membranes derived from human lung epithelial type II cells or human macrophages 62 to capture SARS-CoV-2 and inhibit infection. Similarly, using nanomaterials that can generate free radicals 56 or heat 32 could improve the antiviral efficacy of such approaches.…”

“…Surgical masks are made of three different fibre layers to prevent the entry of viruses; the outside layer is designed to stop liquid splash; the interlayer acts as a barrier against viruses and bacteria; and the inner coating absorbs moisture exhaled by the wearer 30 . Different materials can be synthesized to act as protective coatings, such as polyimide thin films with nanoporous membranes 31 and carbon-based materials 32 . A polymer nanofibre filter, with the surface chemistry optimized to match that of particulate matter, allows both transparency to sunlight and sufficient airflow 33 .…”

Biomedical Science to Tackle the COVID-19 Pandemic: Current Status and Future Perspectives

“…These devices have been fabricated by functionalizing commercially available masks with graphene nanosheets and exhibited unprecedented self-cleaning and photothermal properties owing to the intrinsic physico-chemical properties provided by graphene. This might result in high economic and environmental costs/benefits impact worldwide [ 119 ]. All of these findings evidence that protection equipment, such as face masks worn by healthcare workers and lay public, can benefit from nanomaterials, by incorporating an additional line of defense against surface- and aerosol-persistent pathogens that can result in potential infectious outbreaks [ 80 , 97 ].…”