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Transition Metal Embedded Two-Dimensional C3N4–Graphene Nanocomposite: A Multifunctional Material

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journal contribution
posted on 17.07.2014, 00:00 by Dibyajyoti Ghosh, Ganga Periyasamy, Swapan K. Pati
The lack of intrinsic spin polarization in graphene as well as in its several composites limits their usage as suitable spintronic material. Using long-range dispersion corrected density functional theory, we explore the structural, electronic, magnetic, and optical properties of recently synthesized [Liu, Q.; Zhang, J. Langmuir 2013, 29, 3821−3828] two-dimensional graphitic carbon nitride (g-C3N4) stacked graphene (C3N4@graphene) where 3d transition metals (TMs) are embedded in the cavity of g-C3N4 (TM-C3N4@​graphene). The incorporation of TMs modifies the structure of C3N4@graphene negligibly and keeps graphene almost as in its pristine form. TM inclusion makes the narrow-gap semiconducting C3N4@graphene as metallic. Charge-transfer analysis shows that the TM-C3N4 transfers electrons from the 3d-orbital of TM to the conduction band of graphene, making it n-doped in nature. Importantly, Cr, Fe, Co, and Ni embedded C3N4@graphene shows long-range ferromagnetic coupling among TMs in their ground state. The magnetic ordering appears due to suitable ferromagnetic d–p exchange interaction, which is absent in paramagnetic V- and Mn-C3N4@​graphene sheets. Furthermore, calculated high charge carrier densities of the n-doped graphene layer in these nanocomposites are quite promising for its usage in ultrafast electronics. Performing Heisenberg model based Monte Carlo simulations, we predict the Curie temperatures for Cr- and Fe-C3N4@graphene as 381 and 428 K, respectively. Moreover, these sheets also demonstrate prominent visible light response, which gives us a clue about their probable photocatalytic activity. Thus, the present study exhibits the true multifunctional behavior of TM-C3N4@​graphene by demonstrating its usage in various fields, such as memory devices, spintronics, ultrafast electronics, photocatalysis, etc.