**3. Fabrication of graphene based superhydrophobic coating**

Revealed in December 2019, another lethal SAR-CoV-2 infection begins circling among the people [17] and spreads through the respiratory beds [18]. Additionally, an individual can likewise get in contact with this infection by interacting with the debased articles or exteriors and afterward getting in touch with mouth, nose, or eyes. A new report states that SAR-CoV-2 has a variable life span on different surfaces [19]. In comparison with Cu and cardboard, the adherence of coronavirus is estimated to be greater on the surfaces of plastic and tempered steel. Besides, the infection is affirmed to be steadier on smooth surfaces compared with uneven surfaces like printing/tissue papers, wood, and materials. Much more problematic is the discernible degree of the infection on the outside film of the surgical masks, which is 7 days [16]. These virus-infected touch surfaces, which can retain the virus for longer periods can spread the virus at a faster rate. In the current epidemic circumstance, where the coronavirus infections are dramatically expanding every day worldwide, improvement of the effective enemy of coronavirus protecting surfaces or coatings can be a potential solution for minimizing the spread of the virus through any source [20, 21]. Graphene or graphene derivatives are suitable for their antibacterial properties [22] and the study by Sametband [23] revealed the antiviral characteristics of graphene oxide and slightly reduced sulfuirnc acid treated graphene oxide against herpes simplex virus Type-1 by a specified unique mechanism. Comparable to receptor heparin sulfate cell surface, graphene oxide and its derivatives contain groups of negative charge elements and so the two moieties challenging each other in connection with HSV-1 as shown in **Figure 2**. Nanomaterials can be considered as main inhibitor in defending the Vero cell from the disease. The viral reduction effectiveness of graphene oxide, reduced graphene oxide, graphene oxide-polyvinylpyrrolidone (PVP) composite, graphene oxide poly (diallyl dimethyl ammonium chloride) composite with forerunners graphite

#### **Figure 2.**

*(a) COVID-19 structure [2], (b) pictorial representation of the mechanism of breaking the long chain of virus envelope. Reprinted with the permission from [16].*

and graphite oxide was analyzed by Ye et al. [24]. This research has opened a huge antiviral tendency of graphene oxide against Pseudorabies infection and porcine pestilence looseness of the bowels infection. He concludes that antiviral characteristics of graphene oxide are ascribed to its adversely charged, high-pitched structure. The graphene oxide formed with PVP, non-ionic polymer demonstrated intense antiviral movement, nonetheless, PDDA (cationic polymer) bound graphene oxide uncovered no infection hindrance, proposing negative charge as an essential for antiviral characteristics. Song and other authors [25] has revealed the graphene oxide based label-free technique to identify and sterilize natural infections, for example, Enterovirus 71 and endemic gastrointestinal avian flu an infection, which have incredible ecological strength and less affectability for carbon-based purifiers and detergents. Redox reactions between the graphene oxide layer and the viruses due to the physico-chemical process will act as an important parameter in destroying the viruses. Under higher temperature environment, the antiviral efficiency of the graphene oxide sheet will be improved. Chen and the co-authors [26] revealed that graphene oxide sheets are accounted for to display critical antiviral restraint possibilities towards covered feline COVID and connecting silver particles into graphene oxide structure widens its antiviral capability in the direction of nonenveloped infectious bursal disease virus. Yang et al. [27] synthesized curcumin stacked β-CD functionalized sulfonated graphene composite and researched its antiviral competence beside negative sense respiratory syncytial infection (RSV). The results demonstrated that GSCC could thwart RSV from tainting the host cells by deactivating the contamination clearly and blocking the association of the disease and have prophylactic and medicinal effects towards the contamination. Du et al. [28] researched the antiviral effect of graphene oxide - Silver nanoparticles composite as an afterthought impacts of porcine regenerative and respiratory problem disease. The outcomes propose that the presentation of infection with graphene oxide -Ag NPs composite block the infection to enter the host cell with a accuracy of 59.2% and advances the creation of IFN-invigorating qualities and interferon-α which hinders the infection expansion. Accordingly, Graphene-based surfaces have enormous probability in the improvement of antiviral surfaces and coatings for keeping fouling from harmful and infectious infections including corona virus, and could control the illness transmission [29]. Especially, for coronavirus infection, structures with higher carboxyl groups and less endurance of this infection on Cu surfaces, graphene oxide/reduced graphene oxide -SO3 coatings enhanced with Cu nanoparticles/Cu particles could be a inspiring possibility for the advancement of hostile to coronavirus surfaces. These materials are important in successfully catching and destabilizing the infection structures and limiting their endurance time on different covered surfaces [30]. The schematic representation of the viral restriction process from the graphene or graphene derivative based coatings is understandable from **Figure 3**.

Zhong et al. [31] fabricated graphene layer-based superhydrophobic low-melting temperature nonwoven surgical masks through dual-mode laser-induced forward transfer method with excellent self-cleaning and photo thermal property. These functional masks are reusable after sunlight sterilization because the surface temperature can quickly increase to 80 °C under sunlight. In addition, these functional masks show the tendency of salt-rejection, which increases its usage lifetime. The superhydrophobic surgical masks, which are, produced through roll-to-roll production, give efficient protection against viruses. SEM image of pristine surgical mask reveals that the melt-blown fibers of 20 μm were smooth and exhibiting non-super hydrophobic properties. The wetting tendency of this mask is estimated through a static contact angle, which is observed to be 110o , representing a hydrophobic

*Role of Graphene and Graphene Derived Materials to Fight with COVID-19 DOI: http://dx.doi.org/10.5772/intechopen.96284*

**Figure 3.**

*Sequential representation of the graphene or graphene derivative based coatings in repelling various viruses including coronavirus. Adapted image [30].*

surface. The disadvantage observed with this mask is that the droplets are attaching to the surface. After using dual-mode laser-induced forward transfer method, it was observed that nanostructured flakes were seen on the mask surface varying its size from 100 nm to few micrometers and the contact was observed to be 141o , which represents its superhydrophobicity (**Figure 4**).

The multi-layered masks for combatting COVID-19 need to be designed as per World Health Organization guidelines i.e. the innermost layer should behave like a hydrophilic surface and the rest two layers i.e. middle and outside layers are to be in hydrophobic nature. There are several combinations of different materials and fabrics, which have a greater tendency to increase the efficiency of filtration and breathability. As the porosity of the layer increases from the 3rd layer to the 1st layer, the extent of droplet filtration will also increase (**Figure 5**). He also reveals that tightly woven fabric in the third layer will attain 80% particle filtration efficiency and enhances breathability. The filtration effectiveness of any mas depends on the most penetrating particle size, which is in the range of 0.04–0.4 μm. The extent of MPPS filtration varies with the velocity at which filtration is done, fiber porosity & diameter, and particle size distribution [32].

#### **Figure 4.**

*Contact angle measurement and SEM images on uncoated and coated graphene nonwoven fiber surgical mask Reprinted with the permission from [31].*

#### **Figure 5.**

*Multi-layered masks with varying porosity from hydrophilicity to superhydrophobicity. Reprinted with the permission from [32].*
