https://dspace.iiti.ac.in:8080/jspui/handle/123456789/3647 2026-07-20T20:52:18Z 2026-07-20T20:52:18Z Kushwaha, Ajay Kumar https://dspace.iiti.ac.in:8080/jspui/handle/123456789/18816 2026-07-20T17:05:49Z 2026-01-01T00:00:00Z

Title: Nanoarchitectonics for sustainable supercapacitor electrodes via the upcycling of waste cardboard into graphitic porous carbon Authors: Kushwaha, Ajay Kumar Abstract: In this work, highly porous activated carbon was synthesized from waste cardboard through a single-step pyrolytic route at 600, 700, and 800 °C, and systematically evaluated as an electrode material for aqueous supercapacitors. Structural analysis confirmed the coexistence of graphitic domains and residual CaCO3, with progressive carbon ordering and CaCO3 decomposition at higher temperatures. FESEM and BET measurements revealed a transition from fibrous structures to fragmented, pore-rich carbon, accompanied by a substantial rise in specific surface area at 800 °C. XPS confirmed rich oxygenated functionalities, supporting improved wettability and charge-storage behaviour. Electrochemical studies in a three-electrode configuration demonstrated superior capacitive performance for the 800 °C sample, delivering 688.1 F g−1 at 5 mV s−1 and stable cycling over 5000 cycles. A symmetric two-electrode device further achieved 163.4 F g−1, retained 92.5% capacitance after 1000 cycles and delivered a maximum energy density of approximately 13.6 Wh kg−1 at a power density of 710 W kg−1. Practical demonstrations, including LED illumination and powering a watch, validate its application potential. These findings establish waste cardboard-derived carbon as a sustainable and efficient electrode material for high-performance energy-storage devices. © 2026 Elsevier Masson SAS. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

2026-01-01T00:00:00Z Kumar, Dharmendra Tiwari, Gaurav Dubey, Mrigendra https://dspace.iiti.ac.in:8080/jspui/handle/123456789/18792 2026-07-20T17:05:48Z 2026-01-01T00:00:00Z

Title: Comprehensive review on hydrophobic carbon dots and their multifunctional applications Authors: Kumar, Dharmendra; Tiwari, Gaurav; Dubey, Mrigendra Abstract: Hydrophobic carbon dots have been considered a novel class of functional nanomaterials that integrate surface hydrophobicity with remarkable optical tunability and chemical stability. These nanostructures exhibit excellent physicochemical, photophysical and biocompatible properties, making them promising candidates for optical electronics, anticounterfeiting dual encryption, latent fingerprint detection, bioimaging, sensing, oil–water separation applications, etc. This review critically consolidates various preparation methods and fundamentals of hydrophobicity, and provides brief insight into the fluorescence mechanisms of hydrophobic carbon dots. Overall, this review provides a comprehensive overview of the current status of hydrophobic carbon dots, highlighting the challenges and future opportunities for translating their unique hydrophobicity character into practical performance and technologies. This journal is © The Royal Society of Chemistry, 2026.

2026-01-01T00:00:00Z Singh, Mayank K. Krishnan, Sarathkumar Rai, Dhirendra Kumar https://dspace.iiti.ac.in:8080/jspui/handle/123456789/18807 2026-07-20T17:05:48Z 2026-01-01T00:00:00Z

Title: MXenes for Supercapacitor Applications Authors: Singh, Mayank K.; Krishnan, Sarathkumar; Rai, Dhirendra Kumar Abstract: Owing to their unique physicochemical properties, MXenes, a relatively new class of 2D transition metal carbides, nitrides, and carbonitrides, have emerged as promising electrode materials for next-generation supercapacitors. This chapter provides a comprehensive overview of the synthesis, properties, and applications of MXenes in supercapacitor systems. A discussion of various synthesis strategies, including top-down methods (hydrofluoric acid, alkali, salt, and electrochemical etching) as well as bottom-up techniques (chemical vapor deposition), is given to highlight their influence on MXene structure and performance. The chapter explores the electrical, mechanical, and chemical properties of MXenes, emphasizing their modulation through surface functional groups. Further, it explores the application of MXenes for electric double-layer capacitors (EDLCs), pseudocapacitors, and hybrid systems, both in pristine and composite forms. Specific emphasis is on composites with carbonaceous materials, polymers, metal oxides, and sulfides to enhance electrochemical performance and address the restacking issue in MXenes. The Charge storage mechanisms in MXenes in different electrolytes—acidic, basic, and neutral—have also been discussed. Finally, the chapter outlines the challenges associated with synthesis scalability and material stability, and proposes future research direction for advancing the MXene-based supercapacitors. © 2026 Scrivener Publishing LLC.

2026-01-01T00:00:00Z Kumar, Sourav Korimilli, Eswara Prasad https://dspace.iiti.ac.in:8080/jspui/handle/123456789/18793 2026-07-20T17:05:48Z 2026-01-01T00:00:00Z

Title: Role of cell orientation and crystallographic texture on the wear anisotropy of directed energy deposited 316 L austenitic stainless steel Authors: Kumar, Sourav; Korimilli, Eswara Prasad Abstract: The microstructures and mechanical properties of components additively manufactured using the Directed energy deposition (DED) technique are distinct. DED results in complex cell morphology, meso‑structures of various sizes, and crystallographic textures, etc., which differ in their size and shape on the build plane (BP) and transverse plane (TP). The microstructure of the BP comprises a quasi-equiaxed grain structure and sub-grains with predominantly hexagonal solidification cells, in contrast to the TP, where the grains are columnar with elongated cells. These differences in microstructures often lead to anisotropy in mechanical properties, and the current study investigates the wear anisotropy of 316 L alloys fabricated using DED. Wear experiments are conducted using a Pin-on-disc tribometer on both BP and TP surfaces. The results show that BP surfaces exhibit superior wear resistance as compared to TP, and the analysis of the wear tracks and subsurface deformation regions using scanning electron microscope and Electron Backscatter Diffraction reveals that (i) the regions underneath the wear surface in TP experience severe wear, (ii) a high density of geometrically necessary dislocations is observed under the TP surface. Subsurface nano-hardness mapping reveals four distinct hardness regimes, with the deformation zone extending significantly deeper beneath TP than the BP. These findings highlight the combined roles of cell morphology and crystallographic texture on the wear behaviour of DED 316 L, offering insights for the design of microstructures that exhibit superior wear-resistance. © 2026 Acta Materialia Inc.

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