Green aspects of photocatalysts during corona pandemic: a promising role for the deactivation of COVID-19 virus

Abstract

The selection of a facile, eco-friendly, and effective methodology is the need of the hour for efficient curing of the COVID-19 virus in air, water, and many food products. Recently, semiconductor-based photocatalytic methodologies have provided promising, green, and sustainable approaches to battle against viral activation via the oxidative capabilities of various photocatalysts with excellent performance under moderate conditions and negligible by-products generation as well. Considering this, recent advances in photocatalysis for combating the spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are inclusively highlighted. Starting from the origin to the introduction of the coronavirus, the significant potential of photocatalysis against viral prevention and -disinfection is discussed thoroughly. Various photocatalytic material-based systems including metal-oxides, metal-free and advanced 2D materials (MXenes, MOFs and COFs) are systematically examined to understand the mechanistic insights of virus-disinfection in the human body to fight against COVID-19 disease. Also, a roadmap toward sustainable solutions for ongoing COVID-19 contagion is also presented. Finally, the challenges in this field and future perspectives are comprehensively discussed involving the bottlenecks of current photocatalytic systems along with potential recommendations to deal with upcoming pandemic situations in the future.

Fig. 1. Schematics illustrating (a) structure of SARS-CoV-2 with structural protein and (b) coronavirus inactivation through photocatalysis by the generation of reactive oxidative species (ROS).

Fig. 2. Schematic illustration representing (a) nanocomposite coating and individual components of a surgical mask, (b) viral disinfection via photocatalytic, photo-assisted heat treatment, and hydrophobic self-sterilization operations after sunlight illumination, and (c) digital scans (left) and scanning electron microscopy (SEM, right) results of the uncoated surgical mask (top) and photoactive mask (PAM, bottom) with E. coli after exposure to solar light for 24 h. Reproduced with permission from ref. , copyright American Chemical Society, 2020.

Fig. 3. The proposed mechanism of SARS COV-2 virus inactivation in photocatalysis.

Fig. 4. (a) Schematic of a Co-functionalized TiO₂ nanotube (Co-TNT) based sensing platform for the detection of SARS-CoV-2. Reproduced from ref. with permission from Multidisciplinary Digital Publishing Institute (MDPI), copyright 2020, (b) corona vaccine, and (c) an illustration diagrammatically illustrating the dip-coating technique for tempered glass units with PVA-based Cu–Gr nanocomposite substrates and the mechanism of action for tempered glass surfaces coated with Cu–Gr. Reproduced from ref. with permission from the American Chemical Society, copyright 2020.

Fig. 5. (a) Photoactivation of nanoparticles to produce reactive oxygen species (ROS) during photocatalytic degradation resulting in viral inactivation. (b) Photocatalysis at contaminated NPs coated solid surface upon irradiation, and (c) sequential process for fabricating dual-mode SiO₂@Au@QD fluorescent labels. Reproduced with permission from ref. (Current Opinion in Chemical Engineering, 2019, 1:100716) from Elsevier, 2019 and ref. of the American Chemical Society, copyright 2020.

Fig. 6. (a) Photocatalytic mechanism for bacteriophage f2 inactivation by AgCN photocatalysts under visible light. Reproduced with permission from ref. copyright 2018 Elsevier, (b) possible Z-scheme mechanism for O-g-C₃N₄/HTCC photocatalyst. Reproduced with permission from ref. copyright 2019 Elsevier.

Fig. 7. Schematics representing (a) intrinsic morphology and thickness of laser-induced graphene (LIG) filter, which boosts filtration efficacy (b) SEM image depicting the outer fibrous carpet region of the LIG filter useful to trap larger constituents and aerosols, (c) SEM image showing porous graphene portion possessing tortuous 2.86–8.94 nm pores, which facilitate bacterial and finer particle capture, (d) LIG filter system placed on a vacuum filtration arrangement, (e) schematic depiction of filtration (top) leading to sterilization and Joule-heating assisted depyrogenation (bottom). Reprinted with permission from ref. , copyright American Chemical Society, 2019.

Fig. 8. (a) The mechanism of MXene-dependent viral inhibition of Ti₃C₂T_x to explore viral inhibition activity at the cell surface, and (b) an illustration of antibody-antigen sensing in a FET circuit and change in the drain-source current is achieved by MXene–graphene VSTM deposition. Photograph: courtesy of “Yanxiao Li”. Copyright 2020 and the image is of the free domain.

Fig. 9. (a) MOF filter (CAU-1) using functionalized terephthalic acid ligands for indoor humidity, and microbial growth, to prevent pollution. Reproduced with permission from ref. , copyright American Chemical Society, 2020. And (b) MOF-based filters used in different living areas. Reprinted with permission from ref. , copyright © 2019 Springer Nature Limited, Nature, 2019.

Fig. 10. Roadmap depicting progression toward a sustainable solution for combating viruses through photocatalytic technology.