Browsing by Author "Pawan Kumar Soni"

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Economical synthesis and optimization for few layers graphene by solid carbon sources: domestic CVD technique
(Springer Science and Business Media Deutschland GmbH, 2025) Misba Hussain; Pawan Kumar Soni; Alok Singh
Chemical vapor deposition (CVD) is widely regarded as an effective method for synthesizing high-quality graphene; however, its widespread industrial adoption is limited by high operational costs, complex instrumentation, and scalability challenges. In this study, we present a cost-effective and scalable approach for the synthesis of various graphene-based nanostructures, including few-layer graphene, carbon nanofibers, multilayer graphene (graphene islands), and flower-like graphene sheet morphologies, using a domestic CVD setup and a solid carbon source composed of a naphthalene/camphor mixture. The process optimization was guided by three critical parameters: precursor composition, the axial distance (δ) between the precursor and the substrate, and the carrier gas composition (Ar: H2 ratio). Experimental results demonstrated that a precursor mixture containing 10 wt% naphthalene and 90 wt% camphor, positioned at a distance of δ = 25 cm from the substrate, and processed under an Ar: H2 gas flow ratio of 9:1, yielded graphene with an I2D /IG intensity ratio of 0.6 in Raman spectra, indicative of few-layer graphene formation. High-resolution transmission electron microscopy (HRTEM) was employed to characterize the internal lattice structure of the deposited graphene, while scanning electron microscopy (SEM) provided insights into the surface morphology of the synthesized carbon nanostructures. Additionally, Fourier-transform infrared spectroscopy (FTIR) was utilized to identify surface functional groups associated with the deposited graphene. The outcomes of this study validate the feasibility of an economical and efficient solid-phase CVD method for producing few-layer graphene, offering promising potential for application in diverse engineering and technological domains. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.
Multiple improvements of hydrogen sorption and their mechanism for MgH2 catalyzed through TiH2@Gr
(Elsevier Ltd, 2020) Satish Kumar Verma; Ashish Bhatnagar; Vivek Shukla; Pawan Kumar Soni; Anant Prakash Pandey; Thakur Prasad Yadav; Onkar Nath Srivastava
The present investigation reports the effect of TiH2 templated over graphene (TiH2@Gr) on the hydrogen sorption characteristics of MgH2/Mg. The as synthesized TiH2@Gr leads to significant effect on sorption in MgH2 by the following effects: the first is dehydrogenation of MgH2–TiH2@Gr, which leads to the conversion of some part of TiH2 into TiH1.924. TiH2 together with TiH1.924 works as a better catalyst than TiH2 alone. The second is ball-milling of TiH2@Gr, which produces defective graphene, which also works as co-catalyst. The third is anchoring of TiH2 on graphene, which does not allow the catalyst to agglomerate. The catalytic effect of TiH2@Gr on MgH2 is found to be better than Ti@Gr and TiO2@Gr. The onset desorption temperature for MgH2–TiH2@Gr is ~204 °C, which is 31 °C and 36 °C lower than MgH2–Ti@Gr, MgH2–TiO2@Gr respectively. The better catalytic behavior of TiH2@Gr also persists during de/re-hydrogenation kinetics and cycling study of MgH2. The feasible mechanism for superior catalytic for TiH2@Gr on MgH2 has been put forward. © 2020 Hydrogen Energy Publications LLC
Tuning the electrochemical capacitance of carbon nanosheets by optimizing its thickness through controlling the carbon precursor in salt-template
(John Wiley and Sons Inc, 2023) Achayalingam Ramesh; Sourabh Basu; Vellaichamy Ganesan; Pawan Kumar Soni; Shanmugam Manivannan; Jeyakumar Kandasamy; Michael Sterlin Leo Hudson; Mohammad Abu Shaz
Herein, two-dimensional (2D) carbon nanosheets derived from biomass precursor is successfully synthesized via a cost-effective salt-templated process. Microstructural characterization and Raman spectral analysis of the sample derived from the salt template method reveals the formation of carbon nanosheets. The nanosheet thickness and its capacitance have been altered by varying the carbon precursor to salt-template ratio. From the AFM data, the thickness of the as-prepared thin carbon sheet was measured as ~5.16 nm, and the other thicker carbon sheet thickness was determined to be between 24 and 38 nm. The Brunauer Emmett Teller (BET) analysis shows that the thinner nanosheets possess a high specific surface area (SSA) of 485 m2 g−1, with slit-pore geometry having a total pore volume of 0.29 cm3 g−1. Hence, compared to thicker carbon nanosheets (63.6 F g−1), the thinner carbon nanosheets exhibit superior electrochemical capacitance of 146 F g−1 in an aqueous 6 M KOH electrolyte, without employing any chemical activation. The electrochemical series resistance of as-prepared carbon nanosheet samples was found to be <1 Ω with charge transfer resistances in the range of 0.29 Ω (thicker sheets) to 0.18 Ω (thinner sheets). The specific capacitance and electrochemical properties vary significantly when the nanosheet thickness has been tuned from thicker to thinner by altering the starch ratio in NaCl. The two-electrode cell assembled using thinner carbon nanosheets exhibited the capacitance of 70.1 F g−1 with energy and power densities as 9.7 Wh kg−1 and 20 kW kg−1 respectively. © 2023 John Wiley & Sons, Ltd.