Triazine-based Graphitic Carbon Nitride Research Articles

Hydrogen molecule adsorption on triazine carbon nitride nanosheet decorated with Rh, Ir, Pd, and Pt elements for hydrogen storage applications

As materials for hydrogen storage is one of the most popular form of energy storage materials, therefore hydrogen storage materials has been widely explored. As the active of platinum-group elements, their decoration on the surface of triazine-based graphitic carbon nitride nanosheet as affective hydrogen storage could be explored. Adsorption of hydrogen molecules on the Rh-, Ir-, Pd-, and Pt-decorated onto triazine-based graphitic carbon nitride nanosheets was therefore studied using the periodic DFT method. Based on the most stable configurations of metal-decorated triazine-based graphitic carbon nitride nanosheets, their adsorption abilities on hydrogen molecules are in orders: H2/Ir–g–C3N4 > > H2/Rh–g–C3N4 > H2/Pt–g–C3N4 > H2/Pd–g–C3N4 derivatives for single hydrogen molecule adsorption, and 2H2/Ir–g–C3N4 > > 2H2/Rh–g–C3N4 > > 2H2/Pt–g–C3N4 ~ 2H2/Pt–g–C3N4 derivatives for the second step of the hydrogen molecule adsorption. The Ir–decorated derivative was found as the best hydrogen storage property and its stepwise adsorption energies of three hydrogen molecules of −3.10 eV, −1.23 eV and − 0.03 eV were obtained. All the metal-decorated derivatives were suggested as hydrogen storage materials.

Triazine-Based Graphitic Carbon Nitride Thin Film as a Homogeneous Interphase for Lithium Storage.

Triazine-based graphitic carbon nitride is a semiconductor material constituted of cross-linked triazine units, which differs from widely reported heptazine-based carbon nitrides. Its triazine-based structure gives rise to significantly different physical chemical properties from the latter. However, it is still a great challenge to experimentally synthesize this material. Here, we propose a synthesis strategy via vapor-metal interfacial condensation on a planar copper substrate to realize homogeneous growth of triazine-based graphitic carbon nitride films over large surfaces. The triazine-based motifs are clearly shown in transmission electron microscopy with high in-plane crystallinity. An AB-stacking arrangement of the layers is orientationlly parallel to the substrate surface. Eventually, the as-prepared films show dense electrochemical lithium deposition attributed to homogeneous charge transport within this thin film interphase, making it a promising solution for energy storage.

Hydrogen storage in scandium decorated triazine based g-C3N4: Insights from DFT simulations

Hydrogen is being considered a ‘fuel of the future,’ a viable alternative to fossil fuels in fuel cell vehicles. Using Density Functional Theory simulations, reversible, onboard hydrogen storage in Sc-decorated triazine-based graphitic carbon nitride (g-C3N4) has been explored. Sc atom binds strongly on the g-C3N4 structure with a binding energy of −7.13 eV. Each Sc atom can reversibly bind 7 molecules of hydrogen, giving a net gravimetric storage capacity of 8.55 wt%, an average binding energy of −0.394 eV per H2, and a corresponding desorption temperature of 458.28 K, fulfilling the criteria prescribed by the US Department of Energy. The issue of transition metal clustering has been investigated by computing the diffusion energy barrier (2.79 eV), which may be large enough to hinder the clustering tendencies. The structural integrity of Sc-g-C3N4 has been verified through ab-initio Molecular Dynamics simulations. The interaction mechanism of Sc over g-C3N4 and H2 over Sc-g-C3N4 has been explored using density of states and charge transfer analysis. A flow of charge from valence 3d orbitals of Sc towards vacant orbitals of g-C3N4 during the binding of Sc over g-C3N4 is observed. The binding of H2 on Sc-g-C3N4 may be via Kubas type of interactions which is stronger than physisorption due to net charge gain by H 1s orbital from Sc 3d orbital. Our systematic investigations indicate that Sc-decorated g-C3N4 may be a high-performance material for reversible hydrogen storage applications.

Deposition of triazine-based graphitic carbon nitrideviaplasma-induced polymerisation of melamine

Millisecond plasma pulses are used to convert vaporised melamine into pure TGCN with a large surface area for efficient water splitting.

Azacalix[3]triazines: A Substructure of Triazine-Based Graphitic Carbon Nitride Featuring Anion-π Interactions.

Graphitic carbon nitride (GCN) has garnered broad research interest due to its unique catalytic properties. However, GCN, prepared by general methods, possesses myriad structural defects and it has been difficult to elucidate their intrinsic physical properties. We report the development of azacalix[3]triazines (AC3Ts), a substructure of triazine-based GCN (Tz-GCN). Despite the electron-deficient natures of triazine, AC3Ts capture protons as organic superbases. We reveal the unique anion-π interactions of AC3Ts that alters the ionization potentials of AC3Ts. To the best of our knowledge, these features have not yet been recognized for Tz-GCN. These unveiled features of AC3Ts are expected to expand the usage scope and possibilities for GCNs.

Nanoporous C3N4, C3N5 and C3N6 nanosheets; novel strong semiconductors with low thermal conductivities and appealing optical/electronic properties

Carbon nitride two-dimensional (2D) materials are among the most attractive class of nanomaterials, with wide range of application prospects. As a continuous progress, most recently, two novel carbon nitride 2D lattices of C3N5 and C3N4 have been successfully experimentally realized. Motivated by these latest accomplishments and also by taking into account the well-known C3N4 triazine-based graphitic carbon nitride structures, we predicted two novel C3N6 and C3N4 counterparts. We then conducted extensive density functional theory simulations to explore the thermal stability, mechanical, electronic and optical properties of these novel nanoporous carbon-nitride nanosheets. According to our results all studied nanosheets are found to exhibit desirable thermal stability and mechanical properties. Non-equilibrium molecular dynamics simulations on the basis of machine learning interatomic potentials predict ultralow thermal conductivities for these novel nanosheets. Electronic structure analyses confirm direct band gap semiconducting electronic character and optical calculations reveal the ability of these novel 2D systems to adsorb visible range of light. Extensive first-principles based results by this study provide a comprehensive vision on the stability, mechanical, electronic and optical responses of C3N4, C3N5 and C3N6 as novel 2D semiconductors and suggest them as promising candidates for the design of advanced nanoelectronics and energy storage/conversion systems.

Magnetic properties in Nb/Tc adsorbed gt-C3N4 monolayer

Abstract Basing on ab initio calculations, we investigate the electronic structures and magnetic properties of triazine-based graphitic carbon nitride (gt-C3N4) sheets with adsorbed by Nb and Tc. Both Nb and Tc atoms energetically prefer to be adsorbed on the cavity site. Adsorptions lead to total magnetic moments of 1.00 μB per Nb or Tc atom. The magnetic moments on Nb anti-ferromagnetically couples with those on C and N atoms, but the spins between Nb atoms strongly ferromagneticially couple to each other. The system therefore becomes ferromagnetic (FM) semiconductor with reduced band-gap, and the estimated Curie temperature (TC) is much higher than room temperature. The magnetic moments of Tc adsorbed system ferromagnetically couple with each other. The adsorption of Tc atom changes the semiconducting gt-C3N4 into half metallic material. These findings indicate adsorptions of Nb/Tc lead to various magnetic characters that has potential application in future spintronics.

Electronic structures and magnetic properties in transition metal adsorbed gt-C3N4 monolayer

Abstract Basing on ab initio calculations, we investigate the electronic structures and magnetic properties of triazine-based graphitic carbon nitride (gt-C3N4) sheets with adsorbed transition metals (TM). TM atoms energetically prefer to be adsorbed on the vacancy site. Adsorptions lead to magnetic moments of 1.0, 2.0, 3.0, 3.0, 2.0, and 3.0 μB for Sc, Ti, V, Mn, Fe, and Co, respectively, which originate from the cooperation between ligand field theory and Hund’s rule. Adsorptions result in different types of magnetic behavior that vary with TM. The system remains semiconducting but with reduced band-gap upon the adsorption of Cr or Ni atom. The adsorption of V and Co atoms can transform semiconducting gt-C3N4 into magnetic metallicity and half metallicity, respectively, with an estimated Curie temperature (TC) above room temperature. Sc, Ti, Fe, and Mn adsorption induce anti-ferromagnetism in the host gt-C3N4. These findings indicate adsorptions of TM lead to various magnetic characters that has potential application in future spintronics.

Directional Charge Transport in Layered Two-Dimensional Triazine-Based Graphitic Carbon Nitride.

Triazine-based graphitic carbon nitride (TGCN) is the most recent addition to the family of graphene-type, two-dimensional, and metal-free materials. Although hailed as a promising low-band-gap semiconductor for electronic applications, so far, only its structure and optical properties have been known. Here, we combine direction-dependent electrical measurements and time-resolved optical spectroscopy to determine the macroscopic conductivity and microscopic charge-carrier mobilities in this layered material "beyond graphene". Electrical conductivity along the basal plane of TGCN is 65 times lower than through the stacked layers, as opposed to graphite. Furthermore, we develop a model for this charge-transport behavior based on observed carrier dynamics and random-walk simulations. Our combined methods provide a path towards intrinsic charge transport in a direction-dependent layered semiconductor for applications in field-effect transistors (FETs) and sensors.

Triazine-based graphitic carbon nitride: controllable synthesis and enhanced cataluminescent sensing for formic acid.

A novel preparation method of triazine-based graphitic carbon nitride (g-C3N4) and its application in the cataluminescence (CTL) sensing system is proposed in the present work. Netty triazine-based g-C3N4 were synthesized via a solid and mild strategy, utilizing the copolymerization interaction between guanidine hydrochloride and trimesic acid. The chemical structure, morphology, optical property, and cataluminescence (CTL) sensing characteristics were investigated in detail. Control experiments were carried out to investigate the CTL sensing characteristics of g-C3N4 towards formic acid, which showed the prepared triazine-based g-C3N4 possessed a superior catalytic activity than that of tri-s-triazine. Meanwhile, the prepared g-C3N4 also showed commendable catalytic oxidization selectivity towards formic acid. In view of the advantageous features of low cost, environment friendliness, and long-term stability, triazine-based g-C3N4 was chosen as a highly efficient material to design a CTL sensor for formic acid. Graphical abstract Netty triazine-based g-C3N4 were synthesized via a novel solid and mild strategy, utilizing the copolymerization interaction between guanidine hydrochloride and trimesic acid. Meanwhile, the prepared g-C3N4 also showed commendable catalytic oxidization selectivity towards formic acid. Compared to most CTL sensing materials (metal and metal oxides), g-C3N4 were metal free, low cost, and environmentally friendly; therefore, triazine-based g-C3N4 could be used as a highly efficient CTL sensing material to detect formic acid.

Hybrid triazine-based graphitic carbon nitride and molybdenum disulfide bilayer with and without Li/Mg intercalation: Structural, electronic and optical properties

The structural, electronic and optical properties of hybrid triazine-based graphitic carbon nitride (C3N4) and molybdenum disulfide (MoS2) without and with Li/Mg intercalation are investigated using hybrid density functional theory. Our calculations reveal that the C3N4 and MoS2 monolayer form a heterostructure with type I band alignment. The conduction and valence band offsets are 0.65 and 0.40eV, respectively. Although the band gap and optical absorption of hybrid C3N4-MoS2 exhibit similar features compared to that of MoS2 monolayer, the valence band maximum of C3N4 layer shifts to lower energy, leading to suitable band edges for overall photo-splitting of water. Compared to that of C3N4 and MoS2 monolayer, the hybrid C3N4-MoS2 increases the Li/Mg binding strength though orbitals hybridization as well as increases the electron conductivity.

Ab initio study of aspirin adsorption on single-walled carbon and carbon nitride nanotubes.

Using density functional theory, we investigate the adsorption properties of acetylsalicylic acid (aspirin) on the outer surfaces of a (10,0) carbon nanotube (CNT) and a (8,0) triazine-based graphitic carbon nitride nanotube (CNNT). The adsorption energies for the CNNT and CNT are 0.67 and 0.51 eV, respectively, and hence, the aspirin molecule binds more strongly to the CNNT. The stronger adsorption energy for the binding to the CNNT is ascribed to the high reactivity of its nitrogen atoms with high electron affinity. The CNNT exhibits local electric dipole moments that cause strong charge redistribution in the adsorbed aspirin molecule. The influence of an external electric field on the adsorption of aspirin on the nanotubes is explored by examining modifications in their electronic band structures, partial densities of states, and charge distributions. An electric field applied along a particular direction is found to induce molecular states of aspirin that lie within the in-gap region of the CNNT. This implies that the CNNT can be potentially utilized for the detection of aspirin.

Carbon- and Nitrogen-Based Organic Frameworks.

This Account provides an overview of organic, covalent, porous frameworks and solid-state materials mainly composed of the elements carbon and nitrogen. The structures under consideration are rather diverse and cover a wide spectrum. This Account will summarize current works on the synthetic concepts leading toward those systems and cover the application side where emphasis is set on the exploration of those systems as candidates for unusual high-performance catalysis, electrocatalysis, electrochemical energy storage, and artificial photosynthesis. These issues are motivated by the new global energy cycles and the fact that sustainable technologies should not be based on rare and expensive resources. We therefore present the strategic design of functionality in cost-effective, affordable artificial materials starting from a spectrum of simple synthetic options to end up with carbon- and nitrogen-based porous frameworks. Following the synthetic strategies, we demonstrate how the electronic structure of polymeric frameworks can be tuned and how this can modify property profiles in a very unexpected fashion. Covalent triazine-based frameworks (CTFs), for instance, showed both enormously high energy and high power density in lithium and sodium battery systems. Other C,N-based organic frameworks, such as triazine-based graphitic carbon nitride, are suggested to show promising band gaps for many (photo)electrochemical reactions. Nitrogen-rich carbonaceous frameworks, which are developed from C,N-based organic framework strategies, are highlighted in order to address their promising electrocatalytic properties, such as in the hydrogen evolution reaction, oxygen reduction reaction (ORR), and oxygen evolution reaction (OER). With careful design, those materials can be multifunctional catalysts, such as a bifunctional ORR/OER electrocatalyst. Although the majority of new C,N-based materials are still not competitive with the best (usually nonsustainable candidates) for each application, the framework/N approach as such is still in its infancy and has already moved organic materials to regions where otherwise only traditional noble metals or special inorganic semiconductors are found. As one potential way to enhance the properties of polymeric frameworks, the idea of catalysts having unique active surfaces based on Mott-Schottky heterojunctions and related concepts are addressed. In order to integrate all of the above versatile subjects from synthesis to applications on C,N-based organic frameworks, we begin the discussion with synthetic concepts and strategies for these frameworks to distinguish these systems from typical covalent organic frameworks based on boron oxide rings. Next we focus on the semiconducting properties of C,N-based organic frameworks in order to show a continuous transition between CTFs and other systems, such as graphitic carbon nitrides. At the end, applications of these materials are shown by highlighting their properties in electrochemical energy storage and photo- and electrocatalysis.

Pseudo Jahn–Teller Origin of Buckling Distortions in Two-Dimensional Triazine-Based Graphitic Carbon Nitride (g-C3N4) Sheets

Due to its direct band gap and light mass, the recently synthesized triazine-based, graphitic carbon nitride (TGCN) is considered a promising material for future microelectronics. However, despite the structural similarity with completely planar carbon-only graphene, TGCN sheets are different because of the presence of buckling distortions making the TGCN sheets nonplanar. In this article, we show that the sufficiently strong coupling between the unoccupied molecular orbitals (UMOs) with occupied molecular orbitals (OMOs) leads to pseudo Jahn–Teller distortions (PJT) and consequent buckling of TGCN layers. Doping the TGCN with doubly charged cations such as Be2+ can suppress the PJT distortions resulting in a completely planar structure. A proper understanding of the mechanism of the PJT effect in TGCN is crucial for tailoring properties that are relevant for practical applications.

Structural, electronic and optical properties of a hybrid triazine-based graphitic carbon nitride and graphene nanocomposite

The interfacial effect on the structural, electronic and optical properties of a hybrid triazine-based graphitic carbon nitride and graphene nanocomposite is calculated using the first-principles method. It reveals the favorable stacking pattern utilizing the ab initio thermodynamics approach. The electronic band structure presents that the high carrier mobility is maintained in a hybrid g-CN/G nanocomposite, and a moderate band gap is opened by the interactions between g-C3N4 and graphene. Moreover, the opened band gap can be tuned regularly with the interfacial distance. Based on the analysis of the imaginary part of dielectric function of the graphene, the g-C3N4 monolayer and the hybrid g-CN/G nanocomposite, it is found that the hybrid g-CN/G nanocomposite displays enhanced and extended optical absorption compared to simplex graphene and the g-C3N4 monolayer.

Triazine-based graphitic carbon nitride: a two-dimensional semiconductor.

Graphitic carbon nitride has been predicted to be structurally analogous to carbon-only graphite, yet with an inherent bandgap. We have grown, for the first time, macroscopically large crystalline thin films of triazine-based, graphitic carbon nitride (TGCN) using an ionothermal, interfacial reaction starting with the abundant monomer dicyandiamide. The films consist of stacked, two-dimensional (2D) crystals between a few and several hundreds of atomic layers in thickness. Scanning force and transmission electron microscopy show long-range, in-plane order, while optical spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations corroborate a direct bandgap between 1.6 and 2.0 eV. Thus TGCN is of interest for electronic devices, such as field-effect transistors and light-emitting diodes.

Triazine‐Based Graphitic Carbon Nitride: a Two‐Dimensional Semiconductor

AbstractGraphitic carbon nitride has been predicted to be structurally analogous to carbon‐only graphite, yet with an inherent bandgap. We have grown, for the first time, macroscopically large crystalline thin films of triazine‐based, graphitic carbon nitride (TGCN) using an ionothermal, interfacial reaction starting with the abundant monomer dicyandiamide. The films consist of stacked, two‐dimensional (2D) crystals between a few and several hundreds of atomic layers in thickness. Scanning force and transmission electron microscopy show long‐range, in‐plane order, while optical spectroscopy, X‐ray photoelectron spectroscopy, and density functional theory calculations corroborate a direct bandgap between 1.6 and 2.0 eV. Thus TGCN is of interest for electronic devices, such as field‐effect transistors and light‐emitting diodes.

11 - The Surgery of Endometrial Carcinoma

Carbon nitride two-dimensional (2D) materials are among the most attractive class of nanomaterials, with wide range of application prospects. As a continuous progress, most recently, two novel carbon nitride 2D lattices of C3N5 and C3N4 have been successfully experimentally realized. Motivated by these latest accomplishments and also by taking into account the well-known C3N4 triazine-based graphitic carbon nitride structures, we predicted two novel C3N6 and C3N4 counterparts. We then conducted extensive density functional theory simulations to explore the thermal stability, mechanical, electronic and optical properties of these novel nanoporous carbon-nitride nanosheets. According to our results all studied nanosheets are found to exhibit desirable thermal stability and mechanical properties. Non-equilibrium molecular dynamics simulations on the basis of machine learning interatomic potentials predict ultralow thermal conductivities for these novel nanosheets. Electronic structure analyses confirm direct band gap semiconducting electronic character and optical calculations reveal the ability of these novel 2D systems to adsorb visible range of light. Extensive first-principles based results by this study provide a comprehensive vision on the stability, mechanical, electronic and optical responses of C3N4, C3N5 and C3N6 as novel 2D semiconductors and suggest them as promising candidates for the design of advanced nanoelectronics and energy storage/conversion systems.