Carbon Nitride Catalyst Research Articles

Photoinduced Deoxygenative C2 Arylation of Quinoline N-oxides with Phenylhydrazines to 2-Arylquinolines over Porous Tubular Graphitic Carbon Nitride Semiconductor Photocatalyst.

The photo-induced deoxygenative C2 arylation of quinoline N-oxides to 2-arylquinolines is achieved over a heterogeneous porous tubular graphitic carbon nitride (PTCN) catalyst with phenylhydrazines as arylation reagent. A wide range of quinoline N-oxides can be efficiently transformed into their corresponding 2-arylquinolines under visible light irradiation. Moreover, PTCN catalyst is easily separated and could be reused several times without loss to its original activity.

Self-assembly of decavanadate and Ni(HCO3)2 into nanoparticles anchored on carbon nitride for efficient photocatalytic Minisci-type alkylation

Photocatalysis Minisci-type reactions involving carbon-centered radicals (CCRs) have emerged as a hot and significant topic in the field of organic synthesis chemistry. Herein, we present a nickel-vanadium nanoparticle anchored on carbon nitride catalyst (NiV-CN) and persulfate as a hydrogen atom transfer (HAT) precursor. This catalyst enables the photocatalytic Minisci-type CCR alkylation. The nickel-vanadium nanoparticles are synthesized via electrostatic attraction between [V10O28]6− anions and Ni(HCO3)2, with in situ self-assembly occurring during the hydrothermal process. In the model reaction of 4-methylquinoline with cyclohexane, the NiV-CN catalyst showed high stability, without significant loss its catalytic activity after three cycles. The CCRs was extended to cycloalkanes, adamantanes, and cyclic ethers, which react with quinoline, isoquinoline, and benzothiazole to provide the corresponding products in moderate to excellent yields. Mechanism studies indicate that nickel-vanadium nanoparticles play a crucial role in the formation process of carbon-centered radicals by activating the persulfate precursor into sulfate radicals under visible-light irradiation.

BiW11/Porous carbon nitride catalyst improves charge carrier separation efficiency for enhanced photocatalytic hydrogen evolution

Solar water splitting has received tremendous attention as hydrogen emerges as a promising energy carrier. Carbon nitride (CN) is an ideal candidate for H2 evolution via water splitting on account of its unique optical and electrical properties. To mitigate photoexcited charge carriers recombination that has severely limited the photocatalytic activity of CN, a heterojunction photocatalyst of CN with monovacant bismuth tungstate (Na6[BiW11O38H]·22H2O, noted as BiW11) as a highly efficient photocatalyst is designed. Herein, the porous carbon nitride (PCN) is first fabricated via the gas template method, and then PCN with BiW11 is modified via the impregnation method. Series of BiW11-based PCN composites with different BiW11 loadings (BiW11/PCN-x, x represents the amount of BiW11) are created to merge complementary advantages of both materials. Visible-light-driven photocatalytic properties of BiW11/PCN-x composites have been examined with Na2S/Na2SO3 sacrificial agents. The hydrogen evolution rate of the BiW11/PCN-10 is 2.45 and 1.98 times than that of PCN and BiW11. This extraordinary photocatalytic activity is ascribed to increased attachment sites for catalysts and active centers for hydrogen reduction due to porous structure and significantly facilitated charge separation efficiency through the type-II heterostructure. The resulting composites would be a potential candidate strategy for the design of highly efficient polyoxomatalate-based photocatalysts for efficient hydrogen production applications.

Enhancing solar-driven overall water splitting via both sacrifice and noble metal free photocatalysis: copper cluster/boron-doped carbon nitride catalysts

Enhancing solar-driven overall water splitting via both sacrifice and noble metal free photocatalysis: copper cluster/boron-doped carbon nitride catalysts

Symbolic transform optimized convolutional neural network model for high-performance prediction and analysis of MXenes hydrogen evolution reaction catalysts

Two-dimensional MXenes materials are expected to be cost-effective and efficient catalysts for hydrogen evolution reaction (HER) due to their tunable surface electronic structure. To optimize its catalytic activity, this study proposes a data-driven framework (CROSST) to generate descriptors through feature engineering and integrate them into a convolutional neural network to predict the HER performance of transition-metal (TM) anchored bis-transition-metal carbon-nitride (TM-M′2M′′CNO2) catalysts. The STCNN model achieves a coefficient of determination of more than 0.93, showing the ability to predict the Gibbs free energy of hydrogen adsorption (ΔGH) with high accuracy. We explored the microscopic mechanisms of HER activity through density functional theory and machine learning analysis. It was found that TM anchoring altered the charge distribution of the MXenes material, elevated the atomic orbital occupancy of neighboring O sites, and weakened the O adsorption of H, thus affecting the HER activity. These results provide a theoretical basis for the design of high-performance MXenes HER catalysts and contribute new research perspectives.

Contact-electro-catalytic CO2 reduction from ambient air

Traditional catalytic techniques often encounter obstacles in the search for sustainable solutions for converting CO2 into value-added products because of their high energy consumption and expensive catalysts. Here, we introduce a contact-electro-catalysis approach for CO2 reduction reaction, achieving a CO Faradaic efficiency of 96.24%. The contact-electro-catalysis is driven by a triboelectric nanogenerator consisting of electrospun polyvinylidene fluoride loaded with single Cu atoms-anchored polymeric carbon nitride (Cu-PCN) catalysts and quaternized cellulose nanofibers (CNF). Mechanistic investigation reveals that the single Cu atoms on Cu-PCN can effectively enrich electrons during contact electrification, facilitating electron transfer upon their contact with CO2 adsorbed on quaternized CNF. Furthermore, the strong adsorption of CO2 on quaternized CNF allows efficient CO2 capture at low concentrations, thus enabling the CO2 reduction reaction in the ambient air. Compared to the state-of-the-art air-based CO2 reduction technologies, contact-electro-catalysis achieves a superior CO yield of 33 μmol g−1 h−1. This technique provides a solution for reducing airborne CO2 emissions while advancing chemical sustainability strategy.

Photoinduced Ordered Growth of Copper-Doped Polyaniline Nanotubes: A Method to Improve the Catalytic Activity for C-N Coupling Reactions.

Polyaniline-supported metal nanoparticles (M@PANIs) have been widely employed as catalysts for organic reactions. Traditionally, the catalytic activities of the materials can be improved by introducing functional groups onto the aniline monomers, but it may enhance the catalyst cost and reduce the production yield of the material. This work reports a new strategy for improving the catalytic activity of M@PANIs. It was found that induced by visible light in the presence of a polymeric carbon nitride catalyst and copper dopant, the oxidative polymerization of simple aniline occurred slowly and orderly to produce the copper-doped polyaniline nanotubes. The unique tubular structure protected the catalytically active Cu(I) inside and endowed even more sufficient contact of the catalytic sites with reactants so that the material exhibited excellent catalytic performances in C-N coupling reactions.

Synthesis of polymeric 2D-graphitic carbon nitride (g-C3N4) nanosheets for sustainable photodegradation of organic pollutants

A superficial, one step thermal polycondensation method has been employed for the manifestation of graphene like graphitic carbon nitride (g-C3N4) catalyst. The as synthesized g-C3N4 was well characterized by SEM and EDAX analysis, XRD, ATR-IR, FTIR, Fluorescence spectroscopy, Raman spectroscopy and UV–Visible spectroscopy which provide structural, morphological assemblage relating to the structure of g-C3N4. The g-C3N4 showed that an outstanding photochemical stability, morphology, conductive carbon framework and superior photocatalytic activity. The band gap value of g-C3N4 is 2.34 eV determined using Tauc plot. Due to low band gap (2.33 eV) and unique morphology which provides high separation and migration ability of the photogenerated charges, the g-C3N4 shows enhanced photocatalytic activity for the removal of many organic dyes such as Rhodamine B (RhB), Crystal Violet (CV), Methylene Blue (MB), Methyl Orange (MO), Naphthol Orange (NO) and a phenol derivative, p-Nitrophenol (p-NP). Among them, RhB dye was degraded almost 81 % at 90 min under sunlight irradiation in presence g-C3N4 while other dyes and p-NP was degraded at lower rate. From the experimental data, it was found that MO and p-NP degradation rate was least. The rate constant for degradation of Rh B is 1.1 × 10−2 min−1. Therefore, g-C3N4 can be used as an efficient photocatalyst for waste water treatment by the removal of such organic pollutants.

Ru–modified graphitic carbon nitride for the solar light–driven photocatalytic H2O2 synthesis

Hydrogen peroxide (H2O2) is an efficient and environmentally friendly oxidant as well as a promising energy-carrier alternative to hydrogen. Its solar light-driven photocatalytic synthesis from H2O and O2 is a high-prospect sustainable alternative to the industrial anthraquinone process. Hybrid Ru-modified graphitic carbon nitride (g-C3N4) catalysts were prepared by thermal polymerisation of melamine/Ru(III) acetylacetonate mixtures, and subsequent thermal exfoliation. Simultaneous Ru incorporation and thermal exfoliation impacted the morphology and the structure of the g-C3N4 sheets, and low-atomicity Ru species with small nanoclusters and single atoms were observed only in the Ru-modified exfoliated g-C3N4 photocatalysts. We demonstrated the potential of a joint thermal exfoliation and modification with Ru to enhance the H2O2 synthesis efficiency of the g-C3N4 photocatalyst under simulated sunlight. A volcano-type behavior was observed with increasing the Ru content, and the best performance was obtained for exfoliated g-C3N4 with an ultra-low Ru content of 0.019 wt.%, that outperformed both its bulk counterpart and the pristine exfoliated reference in terms of initial H2O2 synthesis rate and H2O2 formation rate constant. The enhanced performance was attributed to the presence of highly dispersed low atomicity Ru as well as to more accessible active sites and carrier migration channels. Quenching experiments revealed a mixed reactional pathway involving both two-step one-electron and one-step two-electron O2 reduction in the photocatalytic H2O2 production.

The Heptazine-Based Materials through Intrinsically Modification for the Cycloaddition of CO2 and Bisepoxides.

For the efficient utilization of CO2 into valuable product, the attractive carbon nitride catalysts have been widely studied. In this work, heptazine-related materials with varying degree of polymerization were designed by an intrinsically modification strategy and employed in the cycloaddition of CO2 with the bisepoxide 1, 4-butanediol diglycidyl ether (BDODGE). We initially figured out that the sample prepared at 450 °C contained more melem hydrate, exhibiting the best performance. The epoxides conversion and corresponding cyclic carbonates selectivity could achieve 93.1 % and 99.3 % at 140 °C for 20 h without any cocatalyst and solvent, respectively. Results of the catalytic tests suggested that the high catalytic activity was dependent on big size porous structure and the synergetic effect of active amino groups and -OH groups. The role of water in maintaining the specific structure and providing active site has been proved. Moreover, the CN-450-W catalyst exhibited outstanding recycling stability. And finally, a plausible reaction mechanism was proposed.

Metallosalen modified carbon nitride a versatile and reusable catalyst for environmentally friendly aldehyde oxidation

The development of environmentally friendly catalysts for organic transformations is of great importance in the field of green chemistry. Aldehyde oxidation reactions play a crucial role in various industrial processes, including the synthesis of pharmaceuticals, agrochemicals, and fine chemicals. This paper presents the synthesis and evaluation of a new metallosalen carbon nitride catalyst named Co(salen)@g-C3N4. The catalyst was prepared by doping salicylaldehyde onto carbon nitride, and subsequently, incorporating cobalt through Schiff base chemistry. The Co(salen)@g-C3N4 catalyst was characterized using various spectroscopic techniques including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Infrared Spectroscopy (IR), and Thermogravimetric Analysis (TGA). Furthermore, after modification with salicylaldehyde, the carbon nitride component of the catalyst exhibited remarkable yields (74–98%) in oxidizing various aldehyde derivatives (20 examples) to benzoic acid. This oxidation reaction was carried out under mild conditions and resulted in short reaction times (120–300 min). Importantly, the catalyst demonstrated recyclability, as it could be reused for five consecutive runs without any loss of activity. The reusable nature of the catalyst, coupled with its excellent yields in oxidation reactions, makes it a promising and sustainable option for future applications.

A synergistic strategy for the removal and secondary utilization of Cu(II) organic complexes in wastewater for the efficient degradation of tetracycline

Heavy metals in industries such as electroplating plants and semiconductor industries usually exist in the form of heavy metal organic complexes, and the removal of heavy metal organic complexes is troubled by the difficulty of decomplexation as well as the complexity of the treatment process of the free heavy metal ions after decomplexation. In this study, we proposed a synergistic strategy for the removal and secondary utilization of Cu(II) organic complexes (Cu-EDTA) in wastewater through mixed pyrolysis of carbon nitride precursor and Cu-EDTA, and the resulted product was used for the efficient degradation of tetracycline (TC). The unique electronic structure of carbon nitride and abundant surface defects anchor Cu during pyrolysis, which effectively realizes the removal of Cu-EDTA from wastewater. In addition, the Cu and O co-doped carbon nitride (Cu/O-CN) catalyst constructed by this strategy was proved to be effective in peroxydisulfate activation TC degradation, with a removal efficiency of 91.5% in 20 min, a degradation rate of 0.1643 min−1, and a TOC removal efficiency of 53%. X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculation revealed Cu+ active center constructed by the strong metal support interaction between Cu and carbon nitride in Cu/O-CN and the 1O2 dominated nonradical degradation pathways of TC. This study demonstrated a synergistic strategy for the efficient removal and secondary utilization of Cu-EDTA in wastewater, providing new insights into the use of environmentally friendly and cost-effective methods for the removal and recovery of heavy metal organic complexes from wastewater.

Utilizing 2D layered structure Cu-g-C3N4 electrocatalyst for optimizing polysulfide conversion in wide-temperature Li-S batteries

Lithium-sulfur batteries (LSBs) as “post-lithium-ion battery” have gained a high level of visibility due to high energy density and specific capacity. Nevertheless, the commercial production of LSBs is hampered by the the most notorious trouble for shuttling effects of lithium polysulfides (LiPSs). To settle the inherent issues, copper-doped graphitic carbon nitride (Cu-g-C3N4) catalysts with two-dimensional lamellar structures are synthesized using a template method as coating materials for LSBs separators. The substrate material g-C3N4 has a high nitrogen content, which can augment the charge density and significantly enhance the affinity of the materials for LiPSs. Doping of copper atoms in the layered structure of g-C3N4 significantly increases the electrocatalytic activity by creating additional active sites and expediting the redox kinetics of LiPSs for simultaneous S reduction as well as Li2S oxidation. With in-situ UV–vis and theoretical calculations, the efficient activation of bidirectional reaction substantially enhances the rate of solid–liquid-solid reaction, especially solid–solid (Li2S2-Li2S) conversion. As a consequence, the cell with Cu-g-C3N4 shows a satisfied initial discharge capacity of 1469.36 mAh/g at 0.1C. In addition, a high areal capacity of 6.04 mAh/cm2 is achieved under a S loading of 5.10 mg/cm2. Most importantly, the cell with Cu-g-C3N4 maintains stable cycling performance over the scope of a broad temperature (0 °C and 60 °C). This work demonstrates that Cu-g-C3N4 catalysts can be realized for the design of low/high-temperature-resistant LSBs.

Emerging contaminants and pathogenic microorganisms elimination in secondary effluent by graphitic carbon nitride photocatalytic ozonation processes

The complexity of water contaminants, both chemical and biological requires an efficient and feasible treatment alternative. Herein, the photocatalytic ozonation treatment using graphitic carbon nitride catalysts was effectively applied for the elimination of a mixture of targeted chemical contaminants, and both Escherichia coli bacteria and Human polyomavirus JC (JC virus) in real secondary wastewater. The exfoliation treatment was compared in catalysts prepared using urea and melamine as precursors. The physical treatment provided no significant enhancement in the urea-based catalyst, while the improvement in the structure of the melamine-based (36MCN) material and formation of melem heterojunction increased its catalytic properties. In both sets of contaminants, the photocatalytic ozonation systems were superior to photolytic ozonation, especially regarding ozone consumption. The best catalyst, 36MCN, resulted in a decrease of 57.5%, 33.0% and 29.0% in the ozone dose required to eliminate chemical, bacteria and virus contaminants, respectively. The hydroxyl radicals were also shown as a key responsible for the pollutant’s elimination. The higher radical production and decomposition of ozone are possible indications of the better performance of graphitic carbon nitride photocatalytic ozonation, as an efficient tertiary wastewater alternative.

HOFs structured CN template enables the dual regulation of Cu–O and Cu–N active sites in porous Cu-g-CN for synergistic photo-Fenton process

Photo-Fenton catalysis with strong oxidation potential and cyclic stability represents a promising technique for addressing the escalating environmental challenges. However, the photo-Fenton activity using Fe/Cu doped graphitic carbon nitride (g-CN) catalysts is significantly hindered by the limited reaction interface and non-tunable surface-active sites. Herein, we present a novel CN polymer type hydrogen bonded organic framework (CN-HOFs) template derived Cu-g-CN (Cu/CH-g-CN) based hybriding catalyst (CN-HOFs/Cu/CH-g-CN), which process greatly optimized surface features for high-performance photo-Fenton reaction with exceptional durability in a broad pH range of 3–11. Importantly, the distinctive porous structure of CN-HOFs template offers not only high specific surface area, but also the possibility to regulate Cu active sites. The coexistence of Cu–O and Cu–N active sites is identified by XPS, which facilitates the separation and migration of photogenerated charges, expediting the redox cycle. The synergistic photo-Fenton reaction boosted by the porous CN-HOFs structure and the dual Cu active sites (Cu–O and Cu–N) was verified by degradation activity of tetracycline. Under visible light irradiation at a concentration of 20 mg/L, the degradation efficiency reaches nearly 100% within 20 min, with exceptional cycling stability. Further investigations have revealed that the Cu–O active site is conducive to the adsorption of organic pollutants, while the Cu–N active site promotes electron transfer, accelerates the cyclic conversion of Cu+ and Cu2+. The dual copper active site is beneficial for the generation of hydroxyl radicals and the stable operation of the catalyst, resulting in significant photo-Fenton activity. This work underscores the importance of regulating the nanoscale morphology and electronic structure of photofunctional catalysts, not only to increase the active sites for photo-Fenton reactions but also to facilitate charge transfer and the cycling of active metal ions, thereby improving the sustainability of heterogeneous photo-Fenton process.

Study on graphitic carbon nitride catalysts with Bi and Cu loaded for carbon dioxide photothermal reduction

Bi and Cu co-modified g-C3N4 catalysts were prepared by a solvothermal synthesis method, which have excellent CO2 photothermal catalytic reduction activity.

Unleashing solar energy's full potential: Synergetic thermo-photo catalysis for enhanced hydrogen production with metal-free carbon nitrides

Conventional photocatalytic hydrogen production processes are limited by their dependency on photons possessing energy levels surpassing the material's bandgap, thus restricting their ability to utilize the full solar spectrum. Conversely, in thermal catalysis, although the entire solar spectrum is accessible, high-energy photons remain underutilized, and reaction temperatures are often elevated. To address these issues, thermo-photo catalysis is proposed to effectively harness the full spectrum of solar energy under gentle conditions. In this study, a narrow-bandgap carbon nitride catalyst with a bandgap of 2.3 eV was synthesized for the specific purpose of hydrogen production from water through thermo-photo catalysis. Results revealed that under thermo-photo catalytic (TPC) conditions, impressive hydrogen generation rates of 3009.6 μmol·g−1·h−1 and 7090.7 μmol·g−1·h−1 were achieved without and with the application of an external heat source, respectively. Both of them substantially surpassed the cumulative hydrogen production rates achieved via photocatalytic (PC) and thermocatalytic (TC) pathways, demonstrating a remarkable synergy between photonic and thermal energies in the hydrogen evolution process. The synergetic factor with an external heat source applied (2.29) was lower than that without an external heat source (3.02), indicating that there is a better synergy between the photo energy and the thermal energy provided by photothermal conversion than the thermal energy supplied by external heat sources. The properties of photo-generated carriers under various temperature regimes were further examined by photoelectrochemically tests, and electron paramagnetic resonance experiments elucidated the pivotal influence of both photo and thermal energy on radical species, offering a microscopic understanding of the mechanism responsible for the enhanced hydrogen production rate in thermo-photo catalysis.

Photocatalytic activity of zinc oxide nanorods incorporated graphitic carbon nitride catalyst

Background: Photocatalysts are user-friendly and serve as compatible materials for degrading industrial dye pollutants. This study utilizes zinc oxide/graphitic carbon nitride (ZnO/g-C3N4) nanocomposites against degrading methylene blue (MB). Methods: The hydrothermal method assisted sonication technique was used to fabricate the ZnO/g-C3N4 composite with varying ratios of ZnO/g-C3N4 (1:0.25, 1:0.50, 1:1). The synthesized materials have undergone various sophisticated techniques for finding their physiochemical properties and have been utilized for photodegradation activities. Significant Findings: The characterized results exhibit that the nanoflakes of g-C3N4 were covered with nanorods of zinc oxide when observed through scanning electron microscopy (SEM). Furthermore, the X-ray diffraction (XRD) studies demonstrate that the ZnO/g-C3N4 material was successfully synthesized. The X-ray photoelectron spectra (XPS) and Fourier-transform infrared (FTIR) spectra revealed the present oxidation states and chemical bonding of the materials. The photocatalytic activity results demonstrated that the concentration of ZnO molar ratio in varying g-C3N4 significantly affected the decomposition performance. The ZnO/g-C3N4 (1:0.50) presented a higher rate of degradation, reaching 92% at 120 minutes under UV light and 65% at 240 minutes under visible light irradiation. This could be explained by the mechanism that follows the separation of charge carriers, thereby producing hydroxyl radicals for the effective degradation of MB pollutants.

Facile synthesis of FeCeOx nanoparticles encapsulated carbon nitride catalyst for highly efficient and recyclable synthesis of substituted imidazoles

Herein, we developed a novel composite called FeCeOx@g-C3N4 through a combination of sonication, sintering, and hydrothermal techniques to implement the principles of green chemistry by utilizing reusable nanocomposites in one-pot reactions. To gain a comprehensive understanding of the catalyst's structure, composition, and morphology, various characterization methods were employed. These included FT-IR analysis to examine chemical bonds, SEM and TEM imaging to visualize the catalyst's surface and internal structure, TGA to assess thermal stability, EDS for elemental composition analysis, and XRD to determine crystal structure. The FeCeOx@g-C3N4 nanocatalyst demonstrated remarkable efficacy in the one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazole. Noteworthy features of this catalyst included high percentage yield, mild reaction conditions, short reaction time, and an efficient and straightforward procedure. Furthermore, the FeCeOx@g-C3N4 composite exhibited excellent recyclability and reusability. It could be recycled and reused up to four times without a significant decline in catalytic activity.

Enhancing photocatalytic hydrogen production of carbon nitride: Dominant advantage of crystallinity over mass transfer

Mass transfer enhancement and crystallinity engineering are two prevailing technologies for photocatalyst modification. However, their relative effectiveness in enhancing photocatalytic activity remains unclear due to the lack of rational probing catalysts. In this study, we synthesized two distinct carbon nitride (C3N4) catalysts: one with a high specific surface area (CN-HA) and the other with improved crystallinity (CN-HC). These catalysts served as probes to compare their respective impacts on photocatalytic activities. Comprehensive characterization techniques and density functional theory (DFT) calculation results unveiled that crystallinity played a dominant role in light absorption and charge dynamics, while surface area primarily influenced mass transfer in photocatalysis. Importantly, our findings revealed that crystallinity engineering of photocatalyst achieved a greater impact on photocatalytic hydrogen evolution than that from mass transfer enhancement. Consequently, CN-HC demonstrated a remarkable improvement in photocatalytic performance for hydrogen evolution (6465.4 μmol h−1 g−1), surpassing both C3N4 and CN-HA by 19.4- and 2.4-fold, respectively, accompanied by a high apparent quantum yield of 23.8 % at 420 nm. This study not only unveils the dominant factor influencing the activity of photocatalysts but also provides a modified approach for robust solar fuel production, shedding light on the path toward efficient and sustainable energy conversion.