Synthesis and magnetic properties of stable cobalt nanoparticles decorated reduced graphene oxide sheets in the aqueous
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Synthesis and magnetic properties of stable cobalt nanoparticles decorated reduced graphene oxide sheets in the aqueous medium Neelam Singh1 · J. R. Ansari1 · Mrinal Pal2 · Nguyen T. K. Thanh3 · Tung Le4 · Anindya Datta1 Received: 30 March 2020 / Accepted: 22 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract We have synthesized cobalt nanoparticles-reduced graphene oxide (Co-RGO) nanocomposites. The Co NPs achieve shape variation in different nanocomposites due to the strategic use of variety in the preparation techniques. The transmission electron microscope image of composites confirms the decoration of different shapes of Co NPs on RGO sheets. The magnetic study with the variation of temperature indicates a change in the form of hysteresis loops. This is due to the transition from ferromagnetic to superparamagnetic behavior. We found that cubic-shaped Co NPs while decorating RGO show the highest values for some critical magnetic parameters. Coercivity, magnetic moment, and squareness ratio are these parameters. Besides, the nanocomposite-impregnated aqueous sols are found to be quite stable and could be a potential candidate for inkjet printing and ferrofluid as the squareness ratio (Mr/MS) is very small.
1 Introduction Recently, RGO-based metal nanocomposites have gained considerable attention due to their possible scope of applications in particular sensing [1], energy storage [2, 3], electroand photo-catalysis [4–6]. Noble metals are most suitable for Graphene/RGO-based metal nanocomposites as they delineate high chemical stability, catalytic activity, sensing, etc. However, due to scarcity and high-cost noble metals cannot be the proper choice for large scale production. Instead, researchers are trying to replace noble metal with 3d transition metals as they are readily available and cheap. Among others, researchers extensively used cobalt, one of the readily available essential 3d metals in the catalysis process. Co nanocomposites are also an excellent candidate for * Anindya Datta [email protected] 1
University School of Basic & Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi 110078, India
2
CSIR-Central Glass & Ceramic Research Institute, Council of Scientific & Industrial Research, Kolkata 700032, India
3
UCL Healthcare Biomagnetic and Nanomaterials Laboratories, 3rd Floor, The Royal Institution of Great Britain, 21 Albemarle Street, London W1S 4BS, UK
4
Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
ferrofluid [7], drug delivery [8], hyperthermia treatment [9], and magnetic imaging applications [10]. For such a wide variety of applications, a well-dispersed suspension of magnetic material in a solvent is desirable. For specific applications, the suspension needs to be in the water. As one s-electron from Co gets promoted to p-level due to its placement in a single defect of graphene, leading to “spd” hybridization [11], which results in the in-plane bonding o
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