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

Abstract

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-C 3 N 4 ) stacked graphene (C 3 N 4 @graphene) where 3d transition metals (TMs) are embedded in the cavity of g-C 3 N 4 (TM-C 3 N 4 @ graphene). The incorporation of TMs modifies the structure of C 3 N 4 @graphene negligibly and keeps graphene almost as in its pristine form. TM inclusion makes the narrow-gap semiconducting C 3 N 4 @graphene as metallic. Charge-transfer analysis shows that the TM-C 3 N 4 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 C 3 N 4 @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-C 3 N 4 @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 Crand Fe-C 3 N 4 @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-C 3 N 4 @graphene by demonstrating its usage in various fields, such as memory devices, spintronics, ultrafast electronics, photocatalysis, etc.

Efficient helium separation of graphitic carbon nitride membrane

“…These porous membranes can act as natural molecular sieves, and have great potential for future industrial applications, such as hydrogen [33][34][35][36][37][38][39][40], isotope [41][42][43][44], and other gas separation and purification [45]. Among these porous structures, g-C 3 N 4 has attracted considerable attention owing to its potential applications in solar energy conversion [46][47][48], spintronics devices [49,50], energy storage [51] etc. The framework of g-C 3 N 4 consisting of tri-s-triazine (heptazine) rings was demonstrated to be the most stable allotrope among various 2D carbon nitrides under ambient conditions [52].…”

Half-metallic and magnetic properties in nonmagnetic element embedded graphitic carbon nitride sheets

“…[11][12][13] Theoretically, carbon nitride naturally exists in different phases, [14,15] it was believed that the graphitic structures are the most stable under ambient conditions. [28][29][30] The 5d transition metal-doped tri-s-triazine-based g-C 3 N 4 shows magnetic anisotropy, [29] and -2 -the 3d transition metal-doped cases demonstrated variously structural, electronic, magnetic, and optical properties. Experimental and theoretical studies have confirmed that the coplanar tri-s-triazine based g-C 3 N 4 is more stable than triazine-based one by about 30 KJ mol -1 .…”

“…[5][6][7][8][9][10] In analogy to graphene and BN, graphitic-C 3 N 4 (g-C 3 N 4 ) is of interest due to its promising potential applications in the field of photocatalysis. [23][24][25][26][27][28][29][30][31][32] To improve their performances, generally, chemical doping is an effective strategy to modify the electronic structures and magnetic properties. The widely studied g-C 3 N 4 structure has two phases: the triazine-based structure and the tri-s-triazine-based structure.…”

“…The widely studied g-C 3 N 4 structure has two phases: the triazine-based structure and the tri-s-triazine-based structure. [28,30] Compared with the strength of spin-orbit coupling found in conventional 3d transition metal systems, ferromagnetic 2D materials with magnetism arising from pure sp electron present relatively weak spin-orbit coupling and could give a large spin relaxation time that are more suitable for future-generation spintronic devices. [16][17][18][19] Recently, Zhao [20] and Lin [21] developed ultrasonic exfoliating process and mixed solvent strategy to exfoliate bulk or layered g-C 3 N 4 into monolayered tri-s-triazine-based g-C 3 N 4 .…”

Electron spin-polarization and band gap engineering in carbon-modified graphitic carbon nitrides

“…[8][9][10][11][12] These units are linked together by sp 2 -hybridized nitrogen (or carbon) atoms, which lead to a chemical formula of C 3 N 4 (or C 4 N 3 ), 13,14 or directly joint together via C-C covalent bonds with a chemical formula of C 6 N 6 . Theoretical studies have showed that these graphitic carbon nitride materials exhibit exotic properties such as electron spin-polarization, 16,17 half-metallicity, 18,19 spin-gapless semiconduction, 20,21 and topological nontriviality. Theoretical studies have showed that these graphitic carbon nitride materials exhibit exotic properties such as electron spin-polarization, 16,17 half-metallicity, 18,19 spin-gapless semiconduction, 20,21 and topological nontriviality.…”