Carbon Nitride Nanostructures Research Articles

A Fluorescent g-C3N4 Nanosensor for Detection of Dichromate Ions

Background: Dichromate (Cr2O7 2-) ion is one of the carcinogenic and toxic spices in environment which can easily contaminate the environment due to its high solubility in water. Therefore, a lot of attention has been focused on the detection of Cr2O7 2- with high sensitivity and selectivity. Methods: In present work, nitrogen-rich precursor was used for synthesizing graphitic carbon nitride (g-C3N4) nanostructures through hydrothermal oxidation of g-C3N4 nanosheets. The prepared nanostructures show two distinct fluorescence emissions centered at 368 and 450 nm which are highly sensitive toward Cr2O7 2- ions. Results: The as-prepared g-C3N4 was characterized by several techniques such as Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and fluorescence emission spectra. The XRD pattern of prepared nanostructures illustrated two diffraction patterns (at 13.4° and 27.6°) indicating tri-s-tri-azine-based structures. The g-C3N4 exhibited good selectivity and sensitivity toward Cr2O7 2- among other anions. According to titration test, the detection limit and stern-volmer constant (Ksv) were calculated as 40 nM and 0.13×106 M-1, respectively. The investigation of quenching mechanism shows that Cr2O7 2- may form hydrogen bonding with surface groups of g-C3N4 (such as NH2, OH and COOH) resulted in more fluorescence quenching in comparison with the pure inner filter effect. Conclusion: The g-C3N4 nanostructures were successfully synthesized through the hydrothermal oxidation. The as-prepared g-C3N4 can be used as a highly sensitive fluorescent probe for the selective determination of Cr2O7 2 ion among other anions. The quenching mechanism was experimentally studied. According to reliable responses in real sample tests, it can be proposed that g-C3N4 nanostructure is a suitable sensitive nanosensor for detection of Cr2O7 2 ions in aqueous media.

Engineering the excited state of graphitic carbon nitride nanostructures by covalently bonding with graphene quantum dots

Graphitic carbon nitride (CN) materials have drawn remarkable research attention due to their extraordinary optical properties, which are especially promising for metal-free photocatalysis and photoluminescence. Herein we theoretically study the light absorption, electronic, and excitonic characteristics of covalently hybrid structures of CN quantum dots (CNQDs) and graphene quantum dots (GQDs). Density functional theory (DFT) and time-dependent DFT (TD-DFT) reveal that the relative size of CNQDs and GQDs and chemical modification to GQDs or CNQDs surface are critical determining the absorption and photocatalytic/photoluminescent performances of the as-studied structures. Importantly, the distribution position of the photoexcited electron–hole pair is found to depend on the relative size of CNQDs and GQDs, and chemical groups such as epoxy group may lead to distinct exciton distributions in the CNQD–GQD hybrid structures after attaching them to GQD or CNQD surface as compared to the case of pristine GQD and CNQD, indicating a non-negligible influence of unintended chemical reactions to CNQDs and/or GQDs under working conditions on the efficiencies of the materials for photocatalytic and photoluminescent applications.

Carbon nitride nanotube-based materials for energy and environmental applications: a review of recent progresses

Among the diverse graphitic carbon nitride (CN) nanostructures, CN nanotubes (CNNTs) are currently attracting increasing interest due to the appealing properties of CN and the geometric advantages of one-dimensional (1D) nanotubes.

Synthesis of tubular g-C3N4 via a H2SO4-assisted precursor self-assembly strategy for enhanced photocatalytic degradation of organic pollutant

Nanostructured graphitic carbon nitride (g-C3N4) has attracted enormous attention as a promising visible-light photocatalyst because of its unique physicochemical properties. However, controlling the nanostructure of g-C3N4 is challenging because the most common template methods are high-cost and high-risk intensive as well as tedious. In this work, tubular g-C3N4 is prepared in situ by annealing a melamine-cyanurate supramolecular array, which is conducted through a H2SO4-assisted precursor self-assembly strategy. The as-prepared samples are characterized by X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller analysis, and other photoelectrochemical measurements. Moreover, the band structure of the g-C3N4 nanotubes is investigated to elucidate the carrier separation mechanism. The result shows that the g-C3N4 nanotubes have a hollow structure (average diameter: 0.2–1.2 μm, length: 10–50 μm, and thickness: 15–20 nm) and an enhanced electronic structure. Owing to the high specific surface area of their hierarchical pores and the efficient charge separation of their 1D feature, the g-C3N4 nanotubes exhibit high photocatalytic methylene blue (MB)/tetracycline (TC) degradation rates of 0.0265 min−1 and 0.0110 min−1, which are three and seven times higher than those of Bulk g-C3N4, respectively. Therefore, this study provides a facile and effective strategy for the construction of carbon nitride nanostructures.

Constructing 0D FeP Nanodots/2D g‐C3N4 Nanosheets Heterojunction for Highly Improved Photocatalytic Hydrogen Evolution

AbstractTwo‐dimensional polymeric graphitic carbon nitride (2D g‐C3N4) nanostructures have emerged as a very promising family of photocatalysts for hydrogen evolution from water. Nonetheless, fast recombination of photogenerated charge carriers and the sluggish kinetics of hydrogen evolution reaction (HER) result in unsatisfied solar‐to‐hydrogen efficiency. It is thus greatly encouraging to explore low‐cost and high‐performance co‐catalysts to accelerate the charge transport and to improve the catalytic performance. In this work, for the first time, we report on the fabrication of ultra‐small zero‐dimensional (0D) FeP nanodots anchored on layered 2D g‐C3N4 nanosheets with well‐defined nanostructures and intimate 0D/2D contact interface. The outstanding feature of the material is that the obtained multidimensional heterojunction photocatalysts reveal highly efficient visible‐light‐responsive HER performance in the absence of noble metals. Under an optimal percentage of 4 wt. % FeP, the FeP/g‐C3N4 hybrid showed a remarkable hydrogen‐evolving rate of 215 μmol g−1 h−1 and excellent recycling stability, surpassing noble‐metal Pt modified g‐C3N4 (155 μmol g−1 h−1). The enhancement in HER activity is attributed to the synergistic effects of FeP nanocrystals on the improvement of light‐harvesting property in the visible light region and the acceleration of charge carrier dynamics by well‐constructed interfaces.

Synergistically effective and highly visible light responsive SnO2-g-C3N4 nanostructures for improved photocatalytic and photoelectrochemical performance

This paper reports the facile and scalable fabrication of mesoporous and high surface area tin oxide and tin oxide-graphitic carbon nitride nanostructures {SnO2, SnO2-C3N4 (2 mM) and SnO2-g-C3N4 (4 mM)} using a template-free hydrothermal approach. The overall characterisation revealed a high surface area (~181 m2g−1) with a mesoporous nature, relatively small particle size of SnO2 (~2–3 nm) grown successfully on g-C3N4 sheets, and significantly improved optical behaviour for visible light utilisation. Comparative screening of different SnO2-based nanostructures revealed significant improvements in visible-light induced photocatalytic degradation and photoelectrochemical performance. The visible light-induced degradation of model pollutants, such as Methylene blue (MB) and Congo red (CR), was achieved using SnO2-g-C3N4 (4 mM) with total efficiencies of ~99.38% and ~96%, respectively. The optimal SnO2-g-C3N4 (4 mM) as a photocatalyst showed first order rate constants for MB and CR degradation of 6.39 × 10−2 min−1 and 2.9 × 10−2 min−1, respectively. Moreover, the investigation of different modified photoelectrodes of SnO2-g-C3N4 (4 mM) and SnO2-g-C3N4 (2 mM) show more than eight and five times higher photoelectrochemical performance than that of SnO2, respectively. The possible synergistic effect makes the SnO2-g-C3N4 (4 mM) nanostructure an exceptional photocatalytic and photoresponsive material under visible light that can be used for future environmental and energy-related purposes.

Precise fabrication of porous one-dimensional gC3N4 nanotubes doped with Pd and Cu atoms for efficient CO oxidation and CO2 reduction

Rational design of graphitic carbon nitride nanostructures (gC3N4) is vital for various catalytic applications. Herein, we synthesized porous gC3N4 nanotubes (gC3N4NTs) doped with Pd and Cu (Pd/Cu/gC3N4NTs) via the consecutive polymerization of melamine in an ethylene glycol solution containing the metal precursors followed by annealing. The gC3N4NTs, thus produced, possess a well-defined one-dimensional porous nanotube architecture, large surface area (240 m2 g−1), and a homogenous dispersion of Pd and Cu with no need for templates and/or multistep reactions. This merits the CO oxidation activity of Pd/Cu/gC3N4NTs by 56 °C and 96 °C higher than that of Pd/gC3N4NTs and Cu/gC3N4NTs, respectively. The CO2 reduction activity of Pd/Cu/gC3N4NTs was a 5.5-fold higher than metal-free gC3N4NTs. Also, the UV-light irradiation enhanced the CO2 performance of Pd/Cu/gC3N4NTs by three times. The presented study may pave the way for the utilization of metal-doped gC3N4NTs in various applications.

Probing supramolecular assembly and charge carrier dynamics toward enhanced photocatalytic hydrogen evolution in 2D graphitic carbon nitride nanosheets

Two-dimensional graphitic carbon nitride (2D g-C3N4) nanostructures have been the focus of substantial research interest recently owing to their promising photoactive properties for use in solar-to-fuel conversion. However, the synthesis of 2D g-C3N4 nanomaterials remains a significant challenge. Here we successfully synthesized 2D g-C3N4 nanosheets via a supramolecular chemistry approach. 2D g-C3N4 nanostructures not only enhance the visible light-harvesting property but also provide more catalytic sites for improved hydrogen evolution reaction (HER). More importantly, we describe experimental findings concerning the dynamics of charge and energy transfer by using ultrafast spectroscopy in combination with in-situ electron spin resonance (ESR) characterization. The mechanistic investigation reveals that the introduction of a benzene-substituted melamine motif can remarkably accelerate the electron-hole separation and suppress the recombination of photogenerated charge carriers. The carrier separation dynamics is expected to be tailored by engineering the surface and morphology of g-C3N4, which favors enhanced solar photocatalytic HER efficiency.

Rational synthesis of one-dimensional carbon nitride-based nanofibers atomically doped with Au/Pd for efficient carbon monoxide oxidation

Controlled synthesis of carbon nitride nanostructures doped with noble metal-based catalysts is important in various catalytic applications. Herein, we developed a scalable, facile, and template-free approach for one-pot synthesis of one-dimensional gC3N4 nanofibers co-doped with Au and Pd donated as (Au/Pd/gC3N4NFs). The developed method tailored the high mass production of uniform gC3N4 nanofibers with a great surface area of (85 m2 g−1) and coherently co-doped with Au and Pd. Intriguingly, the complete CO oxidation temperature of Au/Pd/gC3N4NFs (144 °C) is significantly lower than that of Pd/gC3N4NFs (191 °C) and Au/gC3N4NFs (205 °C). The superior activity of Au/Pd/gC3N4NFs is attributed to the combination between outstanding inherent catalytic merits of Au/Pd and the unique physicochemical properties of gC3N4 nanofibers. Our newly designed simple approach may open the way for utilization of gC3N4 nanofibers in CO oxidation reaction.

Quenching-Induced Structural Distortion of Graphitic Carbon Nitride Nanostructures: Enhanced Photocatalytic Activity and Electrochemical Hydrogen Production.

Engineered nanomaterials are emerging in the field of environmental chemistry. This study involves the analysis of the structural, electronic, crystallinity, and morphological changes in graphitic carbon nitride (g-C3N4), an engineered nanomaterial, under rapid cooling conditions. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Brunauer–Emmett–Teller, Fourier transform infrared, Raman, band gap, and Mott–Schottky analyses strongly proved that the liquid N2-quenched sample of g-C3N4 has structural distortion. The photocatalytic efficiency of engineered g-C3N4 nanostructures was analyzed through the degradation of reactive red 120 (RR120), methylene blue (MB), rhodamine B, and bromophenol as a representative dye. The photocatalytic dye degradation efficiency was analyzed by UV–vis spectroscopy and total organic carbon (TOC) analysis. The photocatalytic efficiency of g-C3N4 under different quenching conditions included quenching at room temperature in ice and liquid N2. The degradation efficiencies are found to be 4.2, 14.7, and 82.33% for room-temperature, ice, and liquid N2 conditions, respectively. The pseudo-first-order reaction rate of N2-quenched g-C3N4 is 9 times greater than the ice-quenched g-C3N4. Further, the TOC analysis showed that 55% (MB) and 59% (RR120) of photocatalytic mineralization were achieved within a time duration of 120 min by the liquid N2-quenched g-C3N4 nanostructure. In addition, the quenched g-C3N4 electrocatalytic behavior was examined via the hydrogen (H2) evolution reaction in acidic medium. The liquid N2-quenched g-C3N4 catalyst showed a lower overpotential with high H2 evolution when compared with the other two g-C3N4-quenched samples. The results obtained provide an insight and extend the scope for the application of engineered g-C3N4 nanostructures in the degradation of organic pollutants as well as for H2 evolution.

High-Performance Photoelectrochemical Water Oxidation with Phosphorus-Doped and Metal Phosphide Cocatalyst-Modified g-C3 N4 Formation Through Gas Treatment.

Graphitic carbon nitride (g-C3 N4 ) has been widely explored as a photocatalyst for water splitting. The anodic water oxidation reaction (WOR) remains a major obstacle for such processes, with issues such as low surface area of g-C3 N4 , poor light absorption, and low charge-transfer efficiency. In this work, such longtime concerns have been partially addressed with band gap and surface engineering of nanostructured graphitic carbon nitride (g-C3 N4 ). Specifically, surface area and charge-transfer efficiency are significantly enhanced through architecting g-C3 N4 on nanorod TiO2 to avoid aggregation of layered g-C3 N4 . Moreover, a simple phosphide gas treatment of TiO2 /g-C3 N4 configuration not only narrows the band gap of g-C3 N4 by 0.57 eV shifting it into visible range but also generates in situ a metal phosphide (M=Fe, Cu) water oxidation cocatalyst. This TiO2 /g-C3 N4 /FeP configuration significantly improves charge separation and transfer capability. As a result, our non-noble-metal photoelectrochemical system yields outstanding visible light (>420 nm) photocurrent: approximately 0.3 mA cm-2 at 1.23 V and 1.1 mA cm-2 at 2.0 V versus RHE, which is the highest for a g-C3 N4 -based photoanode. It is expected that the TiO2 /g-C3 N4 /FeP configuration synthesized by a simple phosphide gas treatment will provide new insight for producing robust g-C3 N4 for water oxidation.

Ultralong Nanostructured Carbon Nitride Wires and Self-Standing C-Rich Filters from Supramolecular Microspheres.

The rational design of ultralong carbon nitride nanostructures is highly attractive due to their high aspect ratio alongside their high surface-to-bulk ratio, which make them suitable candidates for various applications such as photocatalysts, water treatment, and sensors. However, the synthesis of ultralong, continuous carbon nitride wires is highly challenging. Here we report the synthesis of 4 cm long and large lateral size carbon nitride wires by utilizing unique supramolecular spheres composed of graphitic carbon nitride (g-CN) monomers as the reactants. In situ scanning electron microscopy studies reveal that upon calcination the g-CN wires spontaneously start to grow from the spheres, while the remaining assembly which acts as a substrate creates self-standing carbon-rich g-CN porous films. The different morphology, chemical composition, and electronic properties of the wires and carbon-rich g-CN allow their utilization as both photocatalyst and water cleaning materials. The g-CN wires exhibit excellent photoactivity for hydrogen production whereas the porous carbon-rich g-CN porous film can be efficiently used for water cleaning applications. The reported work opens opportunities for tailored design of g-CN nanostructures and their use as multifunctional materials for photocatalysis, sensing, and other energy-related applications.

Graphitic carbon nitride/BiOI loaded on electrospun silica nanofibers with enhanced photocatalytic activity

Graphitic carbon nitride (g-C3N4) nanostructures were successfully assembled on silica nanofibers (SiO2 NFs) by an electrospinning technique. Then, BiOI nanosheets (NSs) were uniformly grown on SiO2@g-C3N4 NFs via a facile impregnation method at room temperature. Adjusting the cycle times of the impregnation easily controlled the amount of BiOI NSs on the SiO2@g-C3N4/BiOI NFs. These composite nanofibers exhibited much enhanced photocatalytic activity for the degradation of Rhodamine B (RhB) under visible light irradiation. The first-order rate constant of SiO2@g-C3N4/BiOI NFs was nearly three times that of SiO2@g-C3N4 NFs, and seven times that of SiO2@BiOI NFs. The enhanced photocurrent densities, decreased photoluminescence intensity, and shortened transient photoluminescence life time of SiO2@g-C3N4/BiOI NFs all confirmed the improved charge separation. Active species trapping and electron spin resonance-trap technique demonstrated that the photogenerated holes, OH and O2− are active radicals in the degradation process. And the loaded heterojunctions display a Z-scheme system in photocatalysis. The SiO2@g-C3N4/BiOI NFs with high photocatalytic activity could be easily separated by sedimentation due to the three-dimensional porous network structures of the SiO2 NFs support. Also, the SiO2@g-C3N4/BiOI NFs exhibited high stability and could be reused without much decrease in photocatalytic activity after several recycles.

Band Engineering of Carbon Nitride Monolayers by N-Type, P-Type, and Isoelectronic Doping for Photocatalytic Applications.

Since hydrogen fuel involves the highest energy density among all fuels, production of this gas through the solar water splitting approach has been suggested as a green remedy for greenhouse environmental issues due to extensive consumption of fossil fuels. Low-dimensional materials possessing a large surface-to-volume ratio can be a promising candidate to be used for the photocatalytic approach. Here, we used extensive first-principles calculations to investigate the application of newly fabricated members of two-dimensional carbon nitrides including tg-C3N4, hg-C3N4, C2N, and C3N for water splitting. Band engineering via N-type, P-type, and isoelectronic doping agents such as B, N, P, Si, and Ge was demonstrated for tuning the electronic structure, optimizing solar absorption and band alignment for photocatalysis. Pristine tg-C3N4, hg-C3N4, and C2N crystals involve bandgaps of 3.190, 2.772, and 2.465 eV, respectively, which are not proper for water splitting. Among the dopants, Si and Ge dopants can narrow the band gap of carbon nitrides about 0.5-1.0 eV and also increase their optical absorption in the visible spectrum. This study presents the potential for doping with isoelectronic elements to greatly improve the photocatalytic characteristics of carbon nitride nanostructures.

MOF derived nitrogen-doped carbon polyhedrons decorated on graphitic carbon nitride sheets with enhanced electrochemical capacitive energy storage performance

Three dimensional carbon materials with hirerarchically porous structure could exhibit superior energy storage performance than two dimensional stacked carbon nanosheet materials. In this work, we prepared a novel ZIF-8-derived nitrogen doped carbon nanoparticles/graphitic carbon nitride composite electrode material with high electrochemical energy storage performances, including high specific capacitances (495 F g−1 at 0.1 A g−1 and 188 F g−1 at 20 A g−1) and a stable cycling durability with no capacitance declination after 5000 charge-discharge cycles in three-electrode system. When assembled as electrode materials in symmetrical two-electrode system, the as-prepared composite electrode material could exhibit high specific capacitances of 349.7 F g−1 at 0.5 A g−1 and 261.2 F g−1 at 5 A g−1. Accordingly, a high energy density of 11.89 Wh/kg can be achieved at the power density of 247.40 W kg−1. The improvement stems from its hierarchically porous structure with dominant pore sizes at 3 nm and among 4–40 nm, as well as high exposed pyridinic nitrogen (8.58 at%) and pyrrolic nitrogen (3.59 at%) active sites caused by the insertion of ZIF-8-derived nitrogen doped carbon nanoparticles between g-CN layers. This study has provided a new idea on the design of graphitic carbon nitride nanostructures with improved doping level and hiearchically porous structure.

Photocatalytic properties of nano-structured carbon nitride: a comparison with bulk graphitic carbon nitride

Abstract We have synthesised two kinds of graphitic carbon nitride (g-C3N4) through a pyrolysis process involving urea and melamine. The obtained products were characterised by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflection spectroscopy, and nitrogen adsorption–desorption. The product derived from the urea shows a mesoporous honeycomb-like nanosheet structure (denoted by h-g-C3N4): compared with the bulk product obtained from melamine (denoted by b-g-C3N4), the h-g-C3N4 showed better adsorption and higher photo-activity for rhodamine B (RhB) reduction. The h-g-C3N4 also shows good reusability after cyclic adsorption–regeneration. The present results evinced an efficient design, an eco-friendly and convenient photocatalyst, and a tunable photo-reactivity for use in sustainable light-to-energy conversion.

Influence of porewidening duration on the template assisted growth of graphitic carbon nitride nanostructures

Porous anodic aluminium oxide (AAO) membranes with a highly ordered pore arrangement are typically used as ideal templates for the synthesis of numerous nanostructured materials. Highly ordered templates gained significant attraction due to the fact that they are readily fabricated through self-organised simple anodization process. In this paper, the effect of different pore-widening treatments on the quality of the pores of the AAO templates prepared with different electrolytes were inspected. Results confirmed that, without altering the interpore distance different pore dimensions and diameters of the AAO templates can be easily achieved by chemical pore widening process at room temperature. Also, graphitic carbon nitride nanorods of different dimension have been fabricated from AAO template after porewidening process. These nanostructures are widely used in case of metal free visible light driven photo catalysis, photo degradation of organic pollutants, photo electric conversion and water splitting applications.

Synthesis and photocatalytic properties of graphitic carbon nitride nanofibers using porous anodic alumina templates

In the present study, we describe an effective method for the synthesis of Graphitic carbon nitride (GCN) nanostructures using porous anodic alumina (AAO) membrane as template by simple thermal condensation of cyanamide. Synthesized nanostructure was fully analysed by various techniques to detect its crystalline nature, morphology, luminescent properties followed by the evaluation of its photocatalytic activity in the degradation of Methylene blue dye. Structural analysis of synthesized GCNNF was systematically carried out using x-ray powder diffraction (XRD) and scanning electron microscope (SEM), and. The results confirmed the growth of GCN inside the nanochannels of anodic alumina templates. Luminescent properties of GCNNF were studied using photoluminescence (PL) spectroscopy. PL analysis showed the presence of a strong emission peak in the wavelength range of 350–600 nm in blue region. GCNNF displays higher photocatalytic performance in the photodegradation of methylene blue compare to the bulk GCN.Highlights1. In the present paper, we report the synthesis of graphitic carbon nitride nanofibers (GCNNF) using porous anodic aluminium oxide membranes as templates through thermal condensation of cyanamide at 500 °C.2. The synthesis of Graphitic carbon nitride nanofibers using porous andic alumina template is the efficient approach for increasing crystallinity and surface area.3. The high surface area of graphitic carbon nitride nanofibers has a good impact on novel optical and photocatalytic properties of the bulkGCN.4. AAO templating of GCN is one of the versatile method to produce tailorable GCN nanostructures with higher surface area and less number of structural defects.5. Towards photocatalytic degradation of dyes, the tuning of physical properties is very essential thing hence we are succeeded in achieving better catalytic performance of GCN nanostructures by making use of AAO templates.

Tailored Graphitic Carbon Nitride Nanostructures: Synthesis, Modification, and Sensing Applications

AbstractVarious beneficial properties of graphitic carbon nitride (g‐CN) have been discovered during the promotion of its visible‐light‐driven photocatalytic activity for water splitting. These properties enable g‐CN working as a sensing signal transducer with multiple output modes. In this review, state‐of‐the‐art sensing applications of tailored g‐CN nanostructures in the recent years are presented. Initially, g‐CN nanoarchitectures featuring large surface areas, abundance of active sites, and high dispersity in water are presented along with their preparation methods. Then, sensing applications of these g‐CN nanoarchitectures are described in sequence of the immobilization of recognition elements; semiconductor and electron donating properties derive signaling transduction modes, and efficient approaches for improving sensing performances. The review is concluded with a summary and some perspectives on the challenges and future possibilities of this research field.

Comparison between preparative methodologies of nanostructured carbon nitride and their use as selective photocatalysts in water suspension

Carbon nitride photocatalysts have been prepared by different methodologies, such as chemical ultrasonic irradiation (sonochemical treatment), hydrothermal and ball milling and thermoexfoliation, and have been used for the selective oxidation of 5-hydroxymethyl-2-furaldehyde (HMF) to form 2,5-furandicarboxyaldehyde (FDC) in water suspension both under UV and natural solar irradiation. The physico-chemical features of the photocatalysts have been studied by X-ray diffraction, infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, scanning electron microscopy, and specific surface area measurements. The results indicate that exfoliation of carbon nitrides can increase the conversion of HMF and the selectivity to FDC. In particular, samples exfoliated by both thermal and acidic ultrasonic irradiation treatments showed the best photocatalytic performance.