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The whole world is currently facing a global health crisis due to the coronavirus disease (COVID-19) pandemic caused by SARS coronavirus 2, which started in Wuhan City, China, in December 2019. The pandemic has affected 235 countries, areas or territories and infected over 42 million people across the globe as per WHO update on 27 October 2020. More than 1.1 million people have died and the numbers are increasing daily. However, some drugs have been authorized for emergency treatment of patients, medication and vaccines with proven efficacy to prevent and treat the disease is still under various phases of development. The entire world is consistently making efforts to address three major challenges related to COVID-19 including prevention of its spread, prompt and early diagnosis and treatment of patients to save lives. Touted as one of the game-changing technologies of the century, nanotechnology has huge potential to develop solutions against these three major challenges of the disease. Nanotechnology comprises of multidisciplinary prospects encompassing diverse disciplines including medicine, material science, artificial intelligence, environment, virology, physical sciences, chemistry and biology. The numerous challenges can be addressed through the engineering of the various physicochemical properties of materials presents in abundance in nature. Various claims, studies and reports on research and development to combat these challenges associated with COVID-19 have been collectively discussed in this article from the perspectives of nanotechnology.

Air contamination is one of the foremost concerns of environmentalists worldwide, which has elevated global public health concerns for monitoring air contaminants and implementing appropriate safety policies. These facts have generated nascent global demand for exploring sustainable and translational strategies required to engineer affordable, intelligent, and miniaturized sensors because commercially available sensors lack lower detection limits, room temperature operation, and poor selectivity. The state-of-the-art sensors are concerned with architecting advanced nanomaterials to achieve desired sensing performance. Recent studies demonstrate that neither pristine metal carbides/nitrides (MXenes) nor polymers (P) can address these practical challenges. However, synergistic combinations of various precursors as hybrid-nanocomposites (MXP-HNCs) have emerged as superior sensing materials to develop next-generation intelligent environmental, industrial, and biomedical sensors. The expected outcomes could be manipulative due to optimizing physicochemical and morphological attributes like tunable interlayer-distance, optimum porosity, enlarged effective surface area, rich surface functionalities, mechanical flexibility, and tunable conductivity. This review intends to detail a comprehensive summary of the advancements in state-of-the-art MXP-HNCs chemiresistors. Moreover, the underlying sensing phenomenon, chemiresistor architecture, and their monitoring performance are highlighted. Besides, an overview of challenges, potential solutions, and prospects of MXP-HNCs as next-generation intelligent field-deployable sensors with the integration of IoT and AI are outlined.

Ammonia (NH3) is a vital compound in diversified fields, including agriculture, automotive, chemical, food processing, hydrogen production and storage, and biomedical applications. Its extensive industrial use and emission have emerged hazardous to the ecosystem and have raised global public health concerns for monitoring NH3 emissions and implementing proper safety strategies. These facts created emergent demand for translational and sustainable approaches to design efficient, affordable, and high-performance compact NH3 sensors. Commercially available NH3 sensors possess three major bottlenecks: poor selectivity, low concentration detection, and room-temperature operation. State-of-the-art NH3 sensors are scaling up using advanced nano-systems possessing rapid, selective, efficient, and enhanced detection to overcome these challenges. MXene–polymer nanocomposites (MXP-NCs) are emerging as advanced nanomaterials of choice for NH3 sensing owing to their affordability, excellent conductivity, mechanical flexibility, scalable production, rich surface functionalities, and tunable morphology. The MXP-NCs have demonstrated high performance to develop next-generation intelligent NH3 sensors in agricultural, industrial, and biomedical applications. However, their excellent NH3-sensing features are not articulated in the form of a review. This comprehensive review summarizes state-of-the-art MXP-NCs fabrication techniques, optimization of desired properties, enhanced sensing characteristics, and applications to detect airborne NH3. Furthermore, an overview of challenges, possible solutions, and prospects associated with MXP-NCs is discussed.

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