Exfoliation of Crystalline 2D Carbon Nitride: Thin Sheets, Scrolls and Bundles via Mechanical and Chemical Routes

The local ordering of polar solvents around crystalline carbon nitride nanosheets in solution

The crystalline graphitic carbon nitride, poly-triazine imide (PTI) is highly unusual among layered materials since it is spontaneously soluble in aprotic, polar solvents including dimethylformamide (DMF). The PTI material consists of layers of carbon nitride intercalated with LiBr. When dissolved, the resulting solutions consist of dissolved, luminescent single to multilayer nanosheets of around 60-125 nm in diameter and Li+ and Br- ions originating from the intercalating salt. To understand this unique solubility, the structure of these solutions has been investigated by high-energy X-ray and neutron diffraction. Although the diffraction patterns are dominated by inter-solvent correlations there are clear differences between the X-ray diffraction data of the PTI solution and the solvent in the 4-6 Å-1 range, with real space differences persisting to at least 10 Å. Structural modelling using both neutron and X-ray datasets as a constraint reveal the formation of distinct, dense solvation shells surrounding the nanoparticles with a layer of Br-close to the PTI-solvent interface. This solvent ordering provides a configuration that is energetically favourable underpinning thermodynamically driven PTI dissolution. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 2)'.

On-Surface Carbon Nitride Growth from Polymerization of 2,5,8-Triazido-s-heptazine

Carbon nitrides have recently come into focus for photo- and thermal catalysis, both as support materials for metal nanoparticles as well as photocatalysts themselves. While many approaches for the synthesis of three-dimensional carbon nitride materials are available, only top-down approaches by exfoliation of powders lead to thin-film flakes of this inherently two-dimensional material. Here, we describe an in situ on-surface synthesis of monolayer 2D carbon nitride films as a first step toward precise combination with other 2D materials. Starting with a single monomer precursor, we show that 2,5,8-triazido-s-heptazine can be evaporated intact, deposited on a single crystalline Au(111) or graphite support, and activated via azide decomposition and subsequent coupling to form a covalent polyheptazine network. We demonstrate that the activation can occur in three pathways, via electrons (X-ray illumination), via photons (UV illumination), and thermally. Our work paves the way to coat materials with extended carbon nitride networks that are, as we show, stable under ambient conditions.

Bottom-up Synthesis of Single-Crystalline Poly (Triazine Imide) Nanosheets for Photocatalytic Overall Water Splitting

Poly (triazine imide) (PTI/Li+ Cl- ), one of the crystalline versions of polymeric carbon nitrides, holds great promise for photocatalytic overall water splitting. In principle, the photocatalytic activity of PTI/Li+ Cl- is closely related to the morphology, which could be reasonably tailored by the modulation of the polycondensation process. Herein, we demonstrate that the hexagonal prisms of PTI/Li+ Cl- could be converted to hexagonal nanosheets by adjusting the binary eutectic salts from LiCl/KCl or NaCl/LiCl to ternary LiCl/KCl/NaCl. Results reveal that the extension of in-plane conjugation is preferred, when the polymerisation was performed in the presence of ternary eutectic salts. The hexagonal nanosheets bears longer lifetimes of charge carriers than that of hexagonal prisms due to lower intensity of structure defects and shorter hopping distance of charge carriers along the stacking direction of triazine nanosheets. The optimized hexagonal nanosheets exhibits a record apparent quantum yield value of 25 % (λ=365 nm) for solar hydrogen production by one-step excitation overall water splitting.

On the non-bonding valence band and the electronic properties of poly(triazine imide), a graphitic carbon nitride

Graphitic carbon nitrides are covalently-bonded, layered, and crystalline semiconductors with high thermal and oxidative stability. These properties make graphitic carbon nitrides potentially useful in overcoming the limitations of 0D molecular and 1D polymer semiconductors. In this contribution, we study structural, vibrational, electronic and transport properties of nano-crystals of poly(triazine-imide) (PTI) derivatives with intercalated Li- and Br-ions and without intercalates. Intercalation-free poly(triazine-imide) (PTI-IF) is corrugated or AB stacked and partially exfoliated. We find that the lowest energy electronic transition in PTI is forbidden due to a non-bonding uppermost valence band and that its electroluminescence from the π-π* transition is quenched which severely limits their use as emission layer in electroluminescent devices. THz conductivity in nano-crystalline PTI is up to eight orders of magnitude higher than the macroscopic conductivity of PTI films. We find that the charge carrier density of PTI nano-crystals is among the highest of all known intrinsic semiconductors, however, macroscopic charge transport in films of PTI is limited by disorder at crystal-crystal interfaces. Future device applications of PTI will benefit most from single crystal devices that make use of electron transport in the lowest, π-like conduction band.

Size Effects of the Anions in the Ionothermal Synthesis of Carbon Nitride Materials

Semiconducting carbon nitride polymers are used in metal‐free photocatalysts and in opto‐electronic devices. Conventionally, they are obtained using thermal and ionothermal syntheses in inscrutable, closed systems and therefore, their condensation behavior is poorly understood. Here, the synthetic protocols and properties are compared for two types of carbon nitride materials – 2D layered poly(triazine imide) (PTI) and hydrogen‐bonded melem hydrate – obtained from three low‐melting salt eutectics taken from the systematic series of the alkali metal halides: LiCl/KCl, LiBr/KBr, and LiI/KI. The size of the anion plays a significant role in the formation process of the condensed carbon nitride polymers, and it suggests a strong templating effect. The smaller anions (chloride and bromide) become incorporated into triazine (C₃N₃)‐based PTI frameworks. The larger iodide does not stabilize the formation of a triazine‐based polymer, but instead it leads to the formation of the heptazine (C₆N₇)‐based hydrogen‐bonded melem hydrate as the main crystalline phase. Melem hydrate, obtained as single‐crystalline powders, was compared with PTI in photocatalytic hydrogen evolution from water and in an OLED device. Further, the emergence of each carbon nitride species from its corresponding salt eutectic was rationalized via density functional theory calculations. This study highlights the possibilities to further tailor the properties of eutectic salt melts for ionothermal synthesis of organic functional materials.

Photocatalytic hydrogen evolution based on carbon nitride and organic semiconductors

Photocatalytic hydrogen evolution (PHE) presents a promising way to solve the global energy crisis. Metal-free carbon nitride (CN) and organic semiconductors photocatalysts have drawn intense interests due to their fascinating properties such as tunable molecular structure, electronic states, strong visible-light absorption, low-cost etc. In this paper, the recent progresses of photocatalytic hydrogen production based on organic photocatalysts, including CN, linear polymers, conjugated porous polymers and small molecules, are reviewed, with emphasis on the various strategies to improve PHE efficiency. Finally, the possible future research trends in the organic photocatalysts are prospected.

Development of metal-free layered semiconductors for 2D organic field-effect transistors

To this day, the active components of integrated circuits consist mostly of (semi-)metals. Concerns for raw material supply and pricing aside, the overreliance on (semi-)metals in electronics limits our abilities (i) to tune the properties and composition of the active components, (ii) to freely process their physical dimensions, and (iii) to expand their deployment to applications that require optical transparency, mechanical flexibility, and permeability. 2D organic semiconductors match these criteria more closely. In this review, we discuss a number of 2D organic materials that can facilitate charge transport across and in-between their π-conjugated layers as well as the challenges that arise from modulation and processing of organic polymer semiconductors in electronic devices such as organic field-effect transistors.

Direct growth of crystalline triazine-based graphdiyne using surface-assisted deprotection-polymerisation

Graphdiyne polymers have interesting electronic properties due to their π-conjugated structure and modular composition. Most of the known synthetic pathways for graphdiyne polymers yield amorphous solids because the irreversible formation of carbon–carbon bonds proceeds under kinetic control and because of defects introduced by the inherent chemical lability of terminal alkyne bonds in the monomers. Here, we present a one-pot surface-assisted deprotection/polymerisation protocol for the synthesis of crystalline graphdiynes over a copper surface starting with stable trimethylsilylated alkyne monomers. In comparison to conventional polymerisation protocols, our method yields large-area crystalline thin graphdiyne films and, at the same time, minimises detrimental effects on the monomers like oxidation or cyclotrimerisation side reactions typically associated with terminal alkynes. A detailed study of the reaction mechanism reveals that the deprotection and polymerisation of the monomer is promoted by Cu(ii) oxide/hydroxide species on the as-received copper surface. These findings pave the way for the scalable synthesis of crystalline graphdiyne-based materials as cohesive thin films.

We present a one-pot deprotection/polymerisation protocol for the synthesis of crystalline graphdiynes on top of a copper surface starting with stable trimethylsilylated alkyne monomers.

Graphitic Carbon Nitride Films: Emerging Paradigm for Versatile Applications

Graphitic carbon nitride (g-C₃N₄) is a well-known two-dimensional conjugated polymer semiconductor that has been broadly applied in photocatalysis-related fields. However, further developments of g-C₃N₄, especially in device applications, have been constrained by the inherent limitations of its insoluble nature and particulate properties. Recent breakthroughs in fabrication methods of g-C₃N₄ films have led to innovative and inspiring applications in many fields. In this review, we first summarize the fabrication of continuous and thin films, either supported on substrates or as free-standing membranes. Then, the novel properties and application of g-C₃N₄ films are the focus of the current review. Finally, some underlying challenges and the future developments of g-C₃N₄ films are tentatively discussed. This review is expected to provide a comprehensive and timely summary of g-C₃N₄ film research to the wide audience in the field of conjugated polymer semiconductor-based materials.

Post-annealed graphite carbon nitride nanoplates obtained by sugar-assisted exfoliation with improved visible-light photocatalytic performance

Two-dimensional (2D) graphitic carbon nitride (g-C₃N₄) nanoplates (CNNP) have become a hot research topic in photocatalysis due to their small thickness and large specific surface area that favors charge transport and catalytic surface reactions. However, the wide application of 2D g-C₃N₄ nanoplates prepared by ordinary methods suffers from increased band gaps with a poor solar harvesting capability caused by the strong quantum confinement effect and reduced conjugation distance. In this paper, a facile approach of exfoliation and the following fast thermal treatment of the bulk g-C₃N₄ is proposed to obtain a porous few-layered g-C₃N₄ with nitrogen defects. Due to the preferable crystal, textural, optical and electronic structures, the as-obtained porous CNNP demonstrated a significantly improved photocatalytic activity towards water splitting than the bulk g-C₃N₄ and even the 3 nm-thick CNNP obtained by sugar-assisted exfoliation of the bulk g-C₃N₄. The difference in the enhancement factors between the H₂O splitting and organic decomposition has revealed the effect of N defects. This study offers insightful outlooks on the scalable fabrication of a porous few-layered structure with a promoted photocatalytic performance.

Defect Engineering in Atomic-Layered Graphitic Carbon Nitride for Greatly Extended Visible-Light Photocatalytic Hydrogen Evolution

Defect modulation usually has a great influence on the electronic structures and activities of photocatalysts. Here, atomically layered g-C₃N₄ modified via defect engineering with nitrogen vacancy and cyanogen groups is obtained through two facile steps of thermal treatment (denoted as A-V-g-C₃N₄). Detailed analysis reveals that the atomic-layered graphitic carbon nitride (2.3 nm) with defect engineering modifying provides more active sites and decreases the electron/hole transferring distances. More importantly, the defects that contain nitrogen vacancies and cyanogen groups extend the responsive wavelength to 650 nm, which effectively suppresses the quantum size effect of atomic-layered g-C₃N₄. Therefore, the as-obtained A-V-g-C₃N₄ exhibited a photocatalytic H₂ evolution rate and apparent quantum yield of 3.7 mmol·g^-1·h^-1 and 14.98% (λ > 420 nm), respectively. This work is expected to provide guidance for the rational design of atomic-layered g-C₃N₄.

New nitrides: from high pressure-high temperature synthesis to layered nanomaterials and energy applications

We describe work carried out within our group to explore new transition metal and main group nitride phases synthesized using high pressure-high temperature techniques using X-ray diffraction and spectroscopy at synchrotron sources in the USA, UK and France to establish their structures and physical properties. Along with previously published data, we also highlight additional results that have not been presented elsewhere and that represent new areas for further exploration. We also describe new work being carried out to explore the properties of carbon nitride materials being developed for energy applications and the nature of few-layered carbon nitride nanomaterials with atomically ordered structures that form solutions in polar liquids via thermodynamically driven exfoliation. This article is part of the theme issue 'Fifty years of synchrotron science: achievements and opportunities'.

Formation of an ion-free crystalline carbon nitride and its reversible intercalation with ionic species and molecular water

Crystalline layered carbon nitrides can be inter-converted by simple ion exchange process allowing their properties to be tuned.

The development of processes to tune the properties of materials is essential for the progression of next-generation technologies for catalysis, optoelectronics and sustainability including energy harvesting and conversion. Layered carbon nitrides have also been identified as of significant interest within these fields of application. However, most carbon nitride materials studied to date have poor crystallinity and therefore their properties cannot be readily controlled or easily related to their molecular level or nanoscale structures. Here we report a process for forming a range of crystalline layered carbon nitrides with polytriazine imide (PTI) structures that can be interconverted by simple ion exchange processes, permitting the tunability of their optoelectronic and chemical properties. Notable outcomes of our work are (a) the creation of a crystalline, guest-ion-free PTI compound that (b) can be re-intercalated with ions or molecules using “soft chemistry” approaches. This includes the intercalation of HCl, demonstrating a new ambient pressure route to the layered PTI·xHCl material that was previously only available by a high-pressure-high-temperature route (c). Our work also shows (d) that the intercalant-free (IF-) PTI material spontaneously absorbs up to 10 weight% H₂O from the ambient atmosphere and that this process is reversible, leading to potential applications for membranes and water capture in dry environments.

Metal-Free Graphitic Carbon Nitride Photocatalyst Goes Into Two-Dimensional Time

Graphitic carbon nitride (g-C₃N₄) is always a research hotspot as a metal-free visible-light-responsive photocatalyst, in the field of solar energy conversion (hydrogen-production by water splitting). This critical review summarizes the recent progress in the design and syntheses of two-dimensional (2D) g-C₃N₄ and g-C₃N₄-based nanocomposites, covering (1) the modifications of organic carbon nitrogen precursors, such as by heat treatment, metal or metal-free atoms doping, and modifications with organic functional groups, (2) the influencing factors for the formation of 2D g-C₃N₄ process, including the calcination temperature and protective atmosphere, etc. (3) newly 2D g-C₃N₄ nanosheets prepared from pristine raw materials and bulk g-C₃N₄, and the combination of 2D g-C₃N₄ with other 2D semiconductors or metal atoms as a cocatalyst, and (4) the structures and characteristics of each type of 2D g-C₃N₄ systems, together with their optical absorption band structures and interfacial charge transfers. In addition, the first-principles density functional theory (DFT) calculation of the g-C₃N₄ system has been summarized, and this review provides an insightful outlook on the development of 2D g-C₃N₄ photocatalysts. The comprehensive review is concluded with a summary and future perspective. Moreover, some exciting viewpoints on the challenges, and future directions of 2D g-C₃N₄ photocatalysts are discussed and highlighted in this review. This review can open a new research avenue for the preparation of 2D g-C₃N₄ photocatalysts with good performances.

A New Synthesis Approach for Carbon Nitrides: Poly(triazine imide) and Its Photocatalytic Properties

Poly(triazine imide) (PTI) is a material belonging to the group of carbon nitrides and has shown to have competitive properties compared to melon or g-C₃N₄, especially in photocatalysis. As most of the carbon nitrides, PTI is usually synthesized by thermal or hydrothermal approaches. We present and discuss an alternative synthesis for PTI which exhibits a pH-dependent solubility in aqueous solutions. This synthesis is based on the formation of radicals during electrolysis of an aqueous melamine solution, coupling of resulting melamine radicals and the final formation of PTI. We applied different characterization techniques to identify PTI as the product of this reaction and report the first liquid state NMR experiments on a triazine-based carbon nitride. We show that PTI has a relatively high specific surface area and a pH-dependent adsorption of charged molecules. This tunable adsorption has a significant influence on the photocatalytic properties of PTI, which we investigated in dye degradation experiments.

Single Crystal, Luminescent Carbon Nitride Nanosheets Formed by Spontaneous Dissolution

A primary method for the production of 2D nanosheets is liquid-phase delamination from their 3D layered bulk analogues. Most strategies currently achieve this objective by significant mechanical energy input or chemical modification but these processes are detrimental to the structure and properties of the resulting 2D nanomaterials. Bulk poly(triazine imide) (PTI)-based carbon nitrides are layered materials with a high degree of crystalline order. Here, we demonstrate that these semiconductors are spontaneously soluble in select polar aprotic solvents, that is, without any chemical or physical intervention. In contrast to more aggressive exfoliation strategies, this thermodynamically driven dissolution process perfectly maintains the crystallographic form of the starting material, yielding solutions of defect-free, hexagonal 2D nanosheets with a well-defined size distribution. This pristine nanosheet structure results in narrow, excitation-wavelength-independent photoluminescence emission spectra. Furthermore, by controlling the aggregation state of the nanosheets, we demonstrate that the emission wavelengths can be tuned from narrow UV to broad-band white. This has potential applicability to a range of optoelectronic devices.

Photocatalytic overall water splitting by conjugated semiconductors with crystalline poly(triazine imide) frameworks

Photocatalytic water splitting is an ideal pathway to produce hydrogen for the future energy supply due to the sustainability of solar energy and the mild reaction conditions. In the past four decades, many inorganic semiconductor photocatalysts have been studied for this purpose. In recent years, conjugated polymers, in particular covalent carbon nitride frameworks, have rapidly emerged as a new family of photocatalysts. However, the use of conjugated photocatalysts in overall water splitting in the absence of sacrificial agents has been much less reported. Herein, we used surface kinetic control to photocatalyze overall water splitting by a covalent carbon nitride semiconductor with a crystalline poly(triazine imide) (PTI) frameworks. Our study demonstrates that the loading of a Pt co-catalyst on the PTI surface plays the key role in inducing overall water splitting. The co-deposition of a cobalt species can effectively increase the photocatalytic activity and adjust the ratio of H2 and O2 produced, as well as enhancing the stability of the photocatalyst. The optimal sample with the dual co-catalysts shows an apparent quantum yield of 2.1% for the overall water splitting reaction.

Ultrafast Spectroscopy Reveals Electron-Transfer Cascade That Improves Hydrogen Evolution with Carbon Nitride Photocatalysts

Solar hydrogen generation from water represents a compelling component of a future sustainable energy portfolio. Recently, chemically robust heptazine-based polymers known as graphitic carbon nitrides (g-C₃N₄) have emerged as promising photocatalysts for hydrogen evolution using visible light while withstanding harsh chemical environments. However, since g-C₃N₄ electron-transfer dynamics are poorly understood, rational design rules for improving activity remain unclear. Here, we use visible and near-infrared femtosecond transient absorption (TA) spectroscopy to reveal an electron-transfer cascade that correlates with a near-doubling in photocatalytic activity from 2050 to 3810 μmol h^-1 g^-1 when we infuse a suspension of bulk g-C₃N₄ with 10% mass loading of chemically exfoliated carbon nitride. TA spectroscopy indicates that exfoliated carbon nitride quenches photogenerated electrons on g-C₃N₄ at rates approaching the molecular diffusion limit. The TA signal for photogenerated electrons on g-C₃N₄ decays with a time constant of 1/k_e' = 660 ps in the mixture versus 1/k_e = 4.1 ns in g-C₃N₄ alone. Our TA measurements suggest that the charge generation efficiency in g-C₃N₄ is greater than 65%. Exfoliated carbon nitride, which liberates only trace hydrogen levels when photoexcited directly, does not appear to independently sustain appreciable long-lived charge generation. Thus, the activity enhancement in the two-component infusion evidently results from a cooperative effect in which charge is generated on g-C₃N₄, followed by electron transfer to exfoliated carbon nitride containing photocatalytic chain terminations. This correlation between electron transfer and photocatalytic activity provides new insight into structural modifications for controlling charge separation dynamics and activity of carbon-based photocatalysts.

Tri-s-triazine-Based Crystalline Carbon Nitride Nanosheets for an Improved Hydrogen Evolution

Tri-s-triazine-based crystalline carbon nitride nanosheets (CCNNSs) have been successfully extracted via a conventional and cost-effective sonication-centrifugation process. These CCNNSs possess a highly defined and unambiguous structure with minimal thickness, large aspect ratios, homogeneous tri-s-triazine-based units, and high crystallinity. These tri-s-triazine-based CCNNSs show significantly enhanced photocatalytic hydrogen generation activity under visible light than g-C₃ N₄ , poly (triazine imide)/Li⁺ Cl^- , and bulk tri-s-triazine-based crystalline carbon nitrides. A highly apparent quantum efficiency of 8.57% at 420 nm for hydrogen production from aqueous methanol feedstock can be achieved from tri-s-triazine-based CCNNSs, exceeding most of the reported carbon nitride nanosheets. Benefiting from the inherent structure of 2D crystals, the ultrathin tri-s-triazine-based CCNNSs provide a broad range of application prospects in the fields of bioimaging, and energy storage and conversion.

A Composite Polymeric Carbon Nitride with In Situ Formed Isotype Heterojunctions for Highly Improved Photocatalysis under Visible Light

Introducing heterojunction is an effective way for improving the intrinsic photocatalytic activity of a graphitic carbon nitride (GCN) semiconductor. These heterostructures are mostly introduced by interfacing GCN with foreign materials that normally have entirely different physicochemical properties and show unfavorable compatibility, thus resulting in a limited improvement of the photocatalytic performance of the resultant materials. Herein, a composite polymeric carbon nitride (CPCN) that contains both melon-based GCN and triazine-based crystalline carbon nitride (CCN) is prepared by a simple thermal reaction between lithium chloride and GCN. Thanks to the intimate contact and good compatibility between GCN and CCN, an in situ formed heterojunction acts as a driving force for separating the photogenerated charge carriers in CPCN. As a result, CPCN exhibits a significantly improved photocatalytic performance under visible light irradiation, which is, respectively, 10.6 and 5.3 times as high as those of the GCN and CCN alone. This well designed isotype heterojunction by a coupling of CCN presents an effective avenue for developing efficient GCN photocatalysts.

Photoelectrochemical Conversion from Graphitic C3N4 Quantum Dot Decorated Semiconductor Nanowires

Despite the recent progress of developing graphitic carbon nitride (g-C3N4) as a metal-free photocatalyst, the synthesis of nanostructured g-C3N4 has still remained a complicated and time-consuming approach from its bulk powder, which substantially limits its photoelectrochemical (PEC) applications as well as the potential to form composites with other semiconductors. Different from the labor-intensive methods used before, such as exfoliation or assistant templates, herein, we developed a facile method to synthesize graphitic C3N4 quantum dots (g-CNQDs) directly grown on TiO2 nanowire arrays via a one-step quasi-chemical vapor deposition (CVD) process in a homemade system. The as-synthesized g-CNQDs uniformly covered over the surface of TiO2 nanowires and exhibited attractive photoluminescence (PL) properties. In addition, compared to pristine TiO2, the heterojunction of g-CNQD-decorated TiO2 nanowires showed a substantially enhanced PEC photocurrent density of 3.40 mA/cm(2) at 0 V of applied potential vs Ag/AgCl under simulated solar light (300 mW/cm(2)) and excellent stability with ∼82% of the photocurrent retained after over 10 h of continuous testing, attributed to the quantum and sensitization effects of g-CNQDs. Density functional theory calculations were further carried out to illustrate the synergistic effect of TiO2 and g-CNQD. Our method suggests that a variety of g-CNQD-based composites with other semiconductor nanowires can be synthesized for energy applications.

Graphitic carbon nitride nanoribbon for enhanced visible-light photocatalytic H2 production

Chemical scissors provide a new vision to manufacture unique carbon nitride nanostructures with improved photocatalytic performance.

Polymeric photocatalysts based on graphitic carbon nitride

Semiconductor-based photocatalysis is considered to be an attractive way for solving the worldwide energy shortage and environmental pollution issues. Since the pioneering work in 2009 on graphitic carbon nitride (g-C3N4) for visible-light photocatalytic water splitting, g-C3N4 -based photocatalysis has become a very hot research topic. This review summarizes the recent progress regarding the design and preparation of g-C3N4 -based photocatalysts, including the fabrication and nanostructure design of pristine g-C3N4 , bandgap engineering through atomic-level doping and molecular-level modification, and the preparation of g-C3N4 -based semiconductor composites. Also, the photo-catalytic applications of g-C3N4 -based photocatalysts in the fields of water splitting, CO2 reduction, pollutant degradation, organic syntheses, and bacterial disinfection are reviewed, with emphasis on photocatalysis promoted by carbon materials, non-noble-metal cocatalysts, and Z-scheme heterojunctions. Finally, the concluding remarks are presented and some perspectives regarding the future development of g-C3N4 -based photocatalysts are highlighted.

Post-functionalization of graphitic carbon nitrides by grafting organic molecules: toward C–H bond oxidation using atmospheric oxygen

We present a feasible approach in the post-modification of carbon nitrides for the selective oxidation of 3,5,5-trimethylcyclohex-3-en-1-one.