The fast industrialization/urbanization and increasing population have caused serious environmental issues that we are now facing. These challenging issues may become even worse if no efficient and sustainable solutions can be provided. Recent advances in nanotechnology may provide promising technological solutions to these environmental issues (e.g. pollution prevention, treatment, and remediation). The beauty of nanomaterials is that their morphology (e.g. size and shape), microstructure

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... sphere, wire, tube, belt, and hollow/ porous), composition (e.g. multicomponent nanocomposites), and physical and chemical properties (e.g. optical, electrochemical, magnetic, and catalytic) can be tailored through a well-controlled manner, which are difficult or impossible to be achieved in their bulk counterparts. The intriguing physical and chemical properties of nanomaterials can be readily used to develop unique platforms for various environmental applications, such as high-performance sorbents for pollutant removal and catalytic decomposition of refractory pollutants. In this Special Issue, we have invited eight review articles in the field, aiming to bring over the recent advances and R&D activities in developing emerging nanotechnology for environmental applications. Nowadays, carbon-based nanostructured materials, such as graphene and carbon nanotubes, have attracted increasing attention due to their superior electrical, mechanical, and chemical properties as well as their large specific surface area. In their paper entitled " Graphene and carbon-based nanomaterials as highly efficient adsorbents for oils and organic solvents", Wan et al. demonstrate a variety of promising applications of graphene and carbon-based nanomaterials as high-performance adsorbents for the removal of oils and organic solvents. They survey the synthesis and performance of these materials and discuss the current technical challenges towards their practical applications; more importantly, they propose possible future research directions in this field. In another review article, Hu et al. present a comprehensive review on carbon aerogel materials. They summarize the recent progress on the synthesis of carbon aerogels from resorcinol-formaldehyde resin and graphene and further discuss the relationships between the microstructures of the materials and their corresponding performance in pollutant adsorption, capacitive deionization, and other catalytic applications. Another nice review article in this field is contributed by Jame and Zhou. They provide an interesting review article on electrochemical carbon nanotube filters for water treatment. The electrochemical filter technology endows an additional electro-oxidation capability for the adsorbed organic contaminants, and this technology has been proven to be highly effective in several recent laboratory-scale studies. The authors discuss the working principle, impacting factors, current technical challenges, and some of the latest progress about electrochemical carbon nanotube filters, and propose future research directions that require further and concerted efforts from the field. It should be noted that the fabrication of high-quality carbon-based materials is also crucial for their practical applications, which is well discussed in the paper entitled "Electrospinning: a facile technique for fabricating functional nanofibers for environmental applications". In this article, Wang et al. survey the recent progress of another type of promising carbon materialselectrospun carbon fibers. They present an overview and in-depth discussions on recent advances on the synthesis and applications of carbon fibers in environmental monitoring and water purification. The authors further provide their perspectives on the future development and technical challenges of the electrospinning technique towards environmental applications. The development of high-performance photocatalysts is another key solution for enhancing