Browsing by Author "Ajayan, P. M."

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    Development of a schwarzite-based moving bed 3D printed water treatment system for nanoplastic remediation
    (Royal Society of Chemistry, 2021) Gupta, Bramha; Ambekar, Rushikesh S.; Tromer, Raphael M.; Ghosal, Partha Sarathi; Sinha, Rupal; Majumder, Abhradeep; Kumbhakar, Partha; Ajayan, P. M.; Galvao, Douglas S.; Gupta, Ashok Kumar; Tiwary, Chandra Sekhar; Smalley-Curl Institute
    The impact of micro and nanoplastic debris on our aquatic ecosystem is among the most prominent environmental challenges we face today. In addition, nanoplastics create significant concern for environmentalists because of their toxicity and difficulty in separation and removal. Here we report the development of a 3D printed moving bed water filter (M-3DPWF), which can perform as an efficient nanoplastic scavenger. The enhanced separation of the nanoplastics happens due to the creation of a charged filter material that traps the more surface charged nanoparticles selectively. Synthetic contaminated water from polycarbonate waste has been tested with the filter, and enhanced nanoplastic removal has been achieved. The proposed filtration mechanism of surface-charge based water cleaning is further validated using density function theory (semi-empirical) based simulation. The filter has also shown good structural and mechanical stability in both static and dynamic water conditions. The field suitability of the novel treatment system has also been confirmed using water from various sources, such as sea, river, and pond. Our results suggest that the newly developed water filter can be used for the removal of floating nanoparticles in water as a robust advanced treatment system.
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    Vertical heterostructure of graphite–MoS2 for gas sensing
    (Royal Society of Chemistry, 2024) Tripathi, M.; Deokar, G.; Casanova-Chafer, J.; Jin, J.; Sierra-Castillo, A.; Ogilvie, S. P.; Lee, F.; Iyengar, S. A.; Biswas, A.; Haye, E.; Genovese, A.; Llobet, E.; Colomer, J.-F.; Jurewicz, I.; Gadhamshetty, V.; Ajayan, P. M.; Schwingenschlögl, Udo; Costa, Pedro M. F. J.; Dalton, A. B.
    2D materials, given their form-factor, high surface-to-volume ratio, and chemical functionality have immense use in sensor design. Engineering 2D heterostructures can result in robust combinations of desirable properties but sensor design methodologies require careful considerations about material properties and orientation to maximize sensor response. This study introduces a sensor approach that combines the excellent electrical transport and transduction properties of graphite film with chemical reactivity derived from the edge sites of semiconducting molybdenum disulfide (MoS2) through a two-step chemical vapour deposition method. The resulting vertical heterostructure shows potential for high-performance hybrid chemiresistors for gas sensing. This architecture offers active sensing edge sites across the MoS2 flakes. We detail the growth of vertically oriented MoS2 over a nanoscale graphite film (NGF) cross-section, enhancing the adsorption of analytes such as NO2, NH3, and water vapor. Raman spectroscopy, density functional theory calculations and scanning probe methods elucidate the influence of chemical doping by distinguishing the role of MoS2 edge sites relative to the basal plane. High-resolution imaging techniques confirm the controlled growth of highly crystalline hybrid structures. The MoS2/NGF hybrid structure exhibits exceptional chemiresistive responses at both room and elevated temperatures compared to bare graphitic layers. Quantitative analysis reveals that the sensitivity of this hybrid sensor surpasses other 2D material hybrids, particularly in parts per billion concentrations.