Browsing by Author "Misba Hussain"

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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.
Synthesis and characterizations of graphene/Sm doped BiFeO3 composites photoanode for efficient photo-electrochemical water splitting
(Elsevier Ltd, 2021) Alok K. Vishwakarma; Misba Hussain; Satish K. Verma; Vivek Shukla; M.A. Shaz; O.N. Srivastava
The present study features Bi1-xSmxFeO3 (BSFO) nanoparticles anchored on high-quality, reduced graphene oxide (RGO) sheets via a two-step ultrasonication method for photo-electrochemical (PEC) studies relating to solar hydrogen generation. Sm doping leads to the formation of pure BFO type phase without any secondary phases. The structural, morphological, optical, and local structure analyses of BSFO and BSFO@RGO have been done through X-ray diffraction, scanning electron microscope, UV–Vis spectrophotometer, and Raman spectrometer, respectively. The BSFO nanoparticles have been templated on reduced graphene oxide. The BSFO@RGO has been employed as a photoanode for PEC measurements under the simulated solar irradiation of intensity 100 mW-cm−1. The optimum photoanode has been found with Bi0.95S0.05FO3@RGO. The highest photocurrent density and solar to hydrogen (STH) conversion efficiency have been found as 2.40 mA/cm2 (at 0.5 V vs. saturated calomel electrode) and 2.45%, respectively. Furthermore, the stability of the photoanode against photo corrosion has also been tested by the chronoamperometric technique. During 2 h experiment, the average photocurrent density has been maintained at 1.5 mA/cm2 (at 0 V vs. SCE). The improved photocatalytic activity of BSFO@RGO has been explained based on the effect of doping, better solar spectral response, hindering the recombination loss of photo-generated charge carriers, and fast, facile charge transport. Although earlier studies have used Bi(Sm)FeO3 photoanode, hydrogen production has been observed for the first time in the present investigation to the best of our knowledge. Also, it appears that hydrogen production at zero external bias as observed in the present study suggests a new feature for bandgap tailored BFO. © 2021