Graphitic Carbon Nitride Catalyst Research Articles

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.

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

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

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.

Recyclable Mesoporous Graphitic Carbon Nitride Catalysts for the Sustainable Photoredox Catalyzed Synthesis of Carbonyl Compounds

Recyclable Mesoporous Graphitic Carbon Nitride Catalysts for the Sustainable Photoredox Catalyzed Synthesis of Carbonyl Compounds

Ni-B/Mesoporous Graphitic Carbon Nitride Catalyst Boosts Natural Product Cis-pinane Via Catalytic Reduction of α-Pinene

Cis-pinane is an important chemical intermediate in the chemical industry, mainly originating from the selective hydrogenation product of α-pinene. However, the H2 molecules approach α-pinene in different directions to form different intermediates, resulting in low selectivity of cis-pinane. Therefore, designing new catalyst is supposed to be an efficient way to guide the orientation of products. Although many works have reported the new prepared catalysts can improve the selectivity of hydrogenated products, these works ignore the simplicity of the catalyst preparation process, especially in the carriers. In this work, the new high-efficiency and low-cost catalyst was prepared by introducing non-precious Ni-B reactive sites on a simple process-prepared carriers (Mesoporous graphite carbon nitride, MCN). After optimizing, the conversion and selectivity of α-pinene reached 98.9 and 99.9%. Combined with experimental characterization and density functional theory (DFT) calculation, these desiring results can be attributed to the synergy of Ni-B reactive sites and the large π system of MCN, which is beneficial to the absorption of reactants, and promote the production of target products (cis-pinane) follow a specific reaction route. This work demonstrates that the new prepared catalyst possessed excellent industrial potential to obtain natural product cis-pinane via catalytic reduction of α-pinene.

Visible-light-driven carbonylation reaction over palladium supported on spherical-like graphitic carbon nitride

Exploring sustainable catalysts for the transition-metal-catalyzed carbonylation and acknowledging the corresponding interior mechanism are of great interest. Herein, palladium supported spherical-like graphitic carbon nitride catalyst (Pd@s-CN) was prepared through a microwave-assisted approach, where s-CN with larger surface area was synthesized via an exfoliation and refluxing method. The spherical-like structure of s-CN can offer abundant space preventing the agglomeration of Pd and creating more active sites for carbonylation reaction. Notably, with iodobenzene as the substrate, Pd@s-CN achieved 92% yield of benzoic acid, and its performance was better than that of PdCl2 and Pd/C catalysts. The effects of thermal, light source and catalyst structure were investigated. Ultimately, the reaction mechanism of photocatalytic carbonylation was proposed. This environmentally friendly photocatalytic carbonylation method is expected to provide a new idea for carbonylation and other related organic synthesis reactions.

Catalytic oxidation of polystyrene to aromatic oxygenates over a graphitic carbon nitride catalyst

The continuous increase in manufacturing coupled with the difficulty of recycling of plastic products has generated huge amounts of waste plastics. Most of the existing chemical recycling and upcycling methods suffer from harsh conditions and poor product selectivity. Here we demonstrate a photocatalytic method to oxidize polystyrene to aromatic oxygenates under visible light irradiation using heterogeneous graphitic carbon nitride catalysts. Benzoic acid, acetophenone, and benzaldehyde are the dominant products in the liquid phase when the conversion of polystyrene reaches >90% at 150 °C. For the transformation of 0.5 g polystyrene plastic waste, 0.36 g of the aromatic oxygenates is obtained. The reaction mechanism is also investigated with various characterization methods and procedes via polystyrene activation to form hydroxyl and carbonyl groups over its backbone via C–H bond oxidation which is followed by oxidative bond breakage via C–C activation and further oxidation processes to aromatic oxygenates.

Non-oxidative Propane Dehydrogenation over Vanadium Doped Graphitic Carbon Nitride Catalysts

Non-oxidative Propane Dehydrogenation over Vanadium Doped Graphitic Carbon Nitride Catalysts

Three-dimensional hierarchical flowers-like cobalt-nickel sulfide constructed on graphitic carbon nitride: Bifunctional non-noble electrocatalyst for overall water splitting

Tailoring various micro-nano structured materials by employing different techniques to enhance their porosity and conductivity has captivated significant consideration, making their remarkable electrochemical properties accessible within the area of energy storage devices. Herein we report the impact of graphitic carbon nitride concentration (0.03 ∼ 0.1 g) on nickel-cobalt sulfide morphologies and performance in hydrogen production. Employing the facile hydrothermal method, a cubic crystalline nickel-cobalt sulfide was stabilized on defective layered graphitic carbon nitride nanosheets for overall water splitting. A performance peak was observed in a sample with a graphitic carbon nitride concentration of 50 mg, which not only prevented the agglomeration but also provided a porous structure for enhanced gas diffusivity and charge transfer rates owing to the synergistic Carbon and Nitrogen bonding with Cobalt and Nickel Sulfide. Optimized concentration of graphitic carbon nitride also increased the electrocatalytic active surface area threefold when compared with nickel-cobalt sulfide. The fabricated well-aligned flower-like pattern CoNi2S4/graphitic carbon nitride (50 mg) delivered a low overpotential of 310 mV and 160 mV for oxygen evolution reactions and hydrogen evolution reactions to reach a current density of 30 mA/cm2 and 10 mA/cm2 in alkaline media. The electrolyzer displayed an electrolysis potential of 1.58 V to reach 10 mA/cm2 current density with the long-term durability of 24 h. This strategy depicts a novel approach for utilizing this renowned nickel-cobalt sulfide with graphitic carbon nitride catalyst for the application of alkaline electrocatalytic water splitting.

Porous P, Fe-doped g-C3N4 nanostructure with enhanced photo-Fenton activity for removal of tetracycline hydrochloride: Mechanism insight, DFT calculation and degradation pathways

This study fabricated an efficient P and Fe co-doping graphitic carbon nitride catalyst (Fe– CN/P) by thermal polymerization of melamine, FeCl3, and 2-hydroxyphosphonoacetic acid (HPAA) mixture. The Fe–CN/P catalyst exhibited much better tetracycline hydrochloride (TCH) degradation performance than that of single doping and neat CN. Various characterizations indicated that the introduction of HPAA significantly increased the specific surface area of CN and improved charge separation as well as transfer efficiency. Based on Fe 2p XPS analysis and indirect determination of hydroxyl radical (·OH) content, the separated photogenerated electrons accelerated the reduction of Fe(III) and activated photo-Fenton reaction, resulting in more ·OH species generation. The effect of pH value, catalyst dosages, H2O2 concentration, the type of cations and anions as well as water matrices on the degradation of TCH by Fe–CN/P was systematically investigated. The main degradation pathways of TCH were proposed according to the LC-MS intermediates detection and DFT calculation. The results indicated that reactive oxide species (ROS) were more likely to attack the atoms with high Fukui index (f0). This work provides new ideas for adjusting the morphology and electronic structure of CN to enhance its photo-Fenton catalytic activity.

Reduction of CO2 by Photoelectrochemical Process Using Non‐Oxide Two‐Dimensional Nanomaterials – A Review

AbstractDue to their catalytic characteristics, including highly accessible active sites, excellent charge separation properties, great capability for adsorption of CO2 and H2O due to abundant surface defects, and adjustable electronic features, non‐oxide two‐dimensional nanomaterials have received great attention in areas like water splitting and carbon dioxide (CO2) reduction. There are diverse non‐oxide 2D semiconductors reported in literature, among them this review inspects closely the two‐dimensional transition‐metal dichalcogenides (TMDC), MXene materials, graphitic carbon nitride catalysts, metal‐organic frameworks (MOFs), and the heterojunctions of those. This investigation is expected to stimulate new research to improve the design and possible applications of 2D materials by strategies that involve controlling the structural, optical, and electronic properties impacting the catalysts’ activity, selectivity, and stability for successful application in the CO2 reduction or other catalytic reactions.

Single step production of styrene from benzene by alkenylation over palladium-anchored thermal defect rich graphitic carbon nitride catalyst

Styrene is a widely used monomer in polymer industries for the manufacturing of plastics, rubbers and resins. The commercial styrene production process suffers from disadvantages such as requiring multiple steps, catalyst deactivation, high energy consumption and low yield. To address the aforementioned problems, metal complex catalysed single-step oxidative coupling of benzene and ethylene to styrene have been proposed. The attempts so far for the heterogenization of metal complexes lead to worsening the catalytic performance due to metal leaching or clustering. Here, we have presented a first step towards the development of a heterogeneous catalyst to synthesize styrene directly from benzene and ethylene in a single- step. We have anchored palladium nanoparticles on the thermal defect rich surface of graphitic carbon nitride and prepared a heterogeneous catalyst ([email protected]3N4) that is active for the single-step styrene production. The product and side-products were analysed by gas chromatography coupled with mass spectrometry. To understand the role of active sites, the catalysts were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), Brunauer–Emmett–Teller (BET) and Fourier-transform infrared (FT-IR) spectroscopy techniques. A combination of microscopic and spectroscopic characterization supports the hypothesis that the activity of [email protected]3N4 catalyst is associated with their layered structure, surface defect site, and well-stabilized palladium nanoparticles.

Influence of Lewis and Brønsted acidic sites on graphitic carbon nitride catalyst for aqueous phase conversion of biomass derived monosaccharides to 5-hydroxymethylfurfural

Conversion of saccharides to 5-hydroxymethylfurfural is one of the fundamental steps in the synthesis of biodiesel. In this work, we report on the influence of Lewis and Brønsted acidic sites on metal-free graphitic carbon nitride catalysts for the conversion of monosaccharides to 5-hydroxymethylfurfural. We have examined the Lewis acidic sites by doping boron onto graphitic carbon nitride, and under optimal conditions, a maximal 91% yield of 5-hydroxymethylfurfural has been obtained from fructose. Subsequently, the boron doped graphitic carbon nitride was functionalized with Brønsted acidic group to prepare sulfonic acid functionalized boron doped graphitic carbon nitride, which possesses both Lewis and Brønsted acidic sites. However, the use of sulfonic acid functionalized boron doped graphitic carbon nitride as catalyst resulted in a lower yield (78%) of 5-hydroxymethylfurfural from fructose. In addition, time-dependent nuclear magnetic resonance spectroscopic study, temperature-programmed desorption study, and green metrics calculations have been performed to substantiate our findings. Overall, this work provides valuable insights on the influence of Lewis and Brønsted acidic sites on graphitic carbon nitride for biomass conversion reactions.

PH-dependent oxidation mechanisms over FeCu doped g-C3N4 for ofloxacin degradation via the efficient peroxymonosulfate activation

In this work, bimetallic iron and copper co-doped graphitic carbon nitride catalysts (FeCu-g-C3N4) exhibited pH-dependency in the activation of peroxymonosulfate (PMS) for ofloxacin (OFX) degradation, and the mechanism of the generation of reactive oxygen species (ROS) was correlated to the pH of reaction system. The degradation efficiency of OFX reached to 91% within 120 min at pH of 3.1, while only 70% OFX was removed at pH of 9.0. Furthermore, the mainly generated ROS were identified with quenching experiments and electron spin resonance (ESR). Under acidic condition (pH 3.1), •OH and 1O2 made a major contribution for OFX degradation, while 1O2 was the dominant ROS at alkaline condition (pH 9.0). The bimetallic Fe and Cu and the cyano groups on g-C3N4 were revealed to play critical roles in the activation of PMS. Also, Fe and Cu species were suppressed for PMS activation at alkaline condition, and cyano groups in g-C3N4 were active at both acidic and alkaline conditions. This work provides useful information for the influence on the performance of PMS activation under different conditions for the removal of recalcitrant organic compounds in water.

Toward an Understanding of the Enhanced CO2 Electroreduction in NaCl Electrolyte over CoPc Molecule‐Implanted Graphitic Carbon Nitride Catalyst

AbstractDirect CO2 electrolysis in seawater enables the simultaneous conversion of CO2 into CO and the chlorine ions into Cl2, further meeting downstream industry needs such as phosgene synthesis and also facilitating the net consumption of CO2. As a result, the direct implementation of CO2 electrolysis in seawater is urgently required. Herein, a CoPc molecule‐implanted graphitic carbon nitride nanosheets (CoPc/g‐C3N4) electrocatalyst is prepared via a simple mechanochemistry method. The CoPc/g‐C3N4 with a negatively charged surface and preferential adsorption capability for Na+ can achieve appreciable faradaic efficiency (FE, 89.5%) toward CO with a current density of 16.0 mA cm−2 in natural seawater and also realize long‐term operation for 25 h in simulated seawater. Process monitoring further reveals that the chlorine ions in NaCl electrolyte can modulate the reaction microenvironment around the anode, which in turn has positive effects on the CO2RR in cathode. The CO2RR overall splitting in the simulated seawater exhibits a maximum FE of 98.1% towards CO at cell voltage of 3 V. This work describes the development of a carbon‐coupled CoPc molecular catalyst that can drive the CO2 electrolysis in simulated seawater and provides a promising and energy‐saving coupled reaction system for direct coproduction of CO and Cl2.

LC-MS analysis of nitroguanidine compounds by catalytic reduction using palladium modified graphitic carbon nitride catalyst.

The analysis of compounds of the nitroguanidine family at trace level poses an analytical challenge. Nitroguanidine, 1-methyl-3-nitroguanidine, and 1-methyl-3-nitro-1-nitrosoguanidine, which are addressed in this article, have low lipophilicity, with log(Kow) equal to -0.89, - 0.84, and 0.68, respectively, and as such are not amenable for preconcentration from water. Liquid-liquid extraction and SPE fail to concentrate them from water and it is also not possible to extract them by ion exchange resin even after a pH change. Nitroguanidine and 1-methyl-3-nitroguanidine nitramines are explosives of growing use and thereby growing environmental concern due to lower detonation sensitivity compared to RDX. A sensitive method for the determination of nitroguanidine, 1-methyl-3-nitroguanidine, and 1-methyl-3-nitroso-1-nitroguanidine by reduction to the respective amines and subsequent hydrophobization by derivatization with 4-nitrobenzaldehyde followed by LC-ESI-MS analysis is described. Reduction by sodium borohydride using palladium modified graphitic carbon nitride (Pd/g-C3N4) provided improved sensitivity compared to the traditional palladium modified activated carbon due to the lower adsorption of the reduction products on the carbon nitride substrate. The limit of detection of the method was 10ngL-1 for nitroguanidine, and repeated analyses of spiked effluents and contaminated spring water gave relative standard deviations of 8.8% and 6.5%, respectively. The findings illuminate the great promise of Pd/g-C3N4 as a reduction catalyst for the determination of challenging hydrophilic organic contaminants.

Synergetic effect of functionalized graphitic carbon nitride catalyst and ultrasound in aqueous medium: An efficient and sustainable synthesis of 1,3,5-trisubstituted hexahydro-1,3,5-triazines

Graphitic carbon nitride (g-C3N4) was synthesized by melamine and functionalized by H2SO4 treatment using ultrasound assisted method. As prepared functional carbon nitride (Sg–C3N4) was characterized by diverse analytical technique and used as a reusable catalyst for the preparation of 1,3,5-trisubstituted hexahydro-1,3,5-triazine derivatives using aryl amines and formaldehyde as a reactant in aqueous media under ultrasound irradiation. Different comparable experiments shows that the SO3H functionality of the catalyst show a decisive function in this metal-free approach. In contrast to the conventional process, Sg–C3N4 exhibit 21-fold higher catalytic activity under ultrasound irradiation. Protocol shows significant synergistic effect of ultrasound irradiation with water and catalyst over the reaction. With this synergetic methodology we have found that the reactions are cleaner, highly selective, easy work-up procedure and having appreciable economic advantage. It's give us a chance to make the whole procedure green starting from the beginning.

Synergetic Effect of Functionalized Graphitic Carbon Nitride Catalyst and Ultrasound in Aqueous Medium: An Efficient and Sustainable Synthesis of 1,3,5-Trisubstituted Hexahydro-1,3,5-Triazines

Graphitic carbon nitride (g-C3N4) was synthesized by melamine and functionalized by H2SO4 treatment using ultrasound assisted method. As prepared functional carbon nitride (Sg-C3N4) was characterized by diverse analytical technique and used as a reusable catalyst for the preparation of 1,3,5-trisubstituted hexahydro-1,3,5-triazine derivatives using aryl amines and formaldehyde as a reactant in aqueous media under ultrasound irradiation. Different comparable experiments shows that the SO3H functionality of the catalyst show a decisive function in this metal-free approach. In contrast to the conventional process, Sg-C3N4 exhibit 21-fold higher catalytic activity under ultrasound irradiation. Protocol shows significant synergistic effect of ultrasound irradiation with water and catalyst over the reaction. With this synergetic methodology we have found that the reactions are cleaner, highly selective, easy work-up procedure and having appreciable economic advantage. It’s give us a chance to make the whole procedure green starting from the beginning.

Site-specific role of bifunctional graphitic carbon nitride catalyst for the sustainable synthesis of 3,3-spirocyclic oxindoles in aqueous media.

Functionalized graphitic carbon nitride (Sg-C3N4) has been manufactured and used as a reusable catalyst for the one-pot production of various spiro-pyrano chromenes and spiro indole-3,1′-naphthalene tetracyclic systems in aqueous media. An ultrasound-assisted method has been used for the functionalization of g-C3N4. The catalytic functionalities and the structural integrity of the catalyst were characterized via different analytical tools. The catalytic site-specific role of Sg-C3N4 was confirmed via various control experiments in one-pot reaction sequences. We recognized that Sg-C3N4 acts as a bifunctional acid–base catalyst for the first reaction sequence whereas it is an acidic catalyst for the second reaction sequence during the one-pot production of various spiro-pyrano chromenes. In addition, the bifunctional acid–base catalytic role of Sg-C3N4 has been confirmed for the first reaction sequence whereas it has a basic catalytic role for the second reaction sequence during the one-pot production of spiro indole-3,1′-naphthalene tetracyclic systems. Diverse C–C, C–O, and C–N bonds, six-membered cycles, stereogenic centers, and spiro frameworks were formed in a single reaction, enhancing the biocidal profile and possibly resulting in the discovery of new medicinal properties. The mild reaction environment, simple workup, easy separation, low cost, heterogeneity, and recyclability of Sg-C3N4 are some rewards of this approach.

Metal-doped (Fe, Nd, Ce, Zr, U) graphitic carbon nitride catalysts enhance thermal decomposition of ammonium perchlorate-based molecular perovskite

In this paper, we studied the effect of M-doped graphitic carbon nitride (M-g-C3N4, M = Fe, Nd, Ce, Zr, U) as a catalyst for the thermal decomposition of ammonium perchlorate-based molecular perovskite DAP-4. DAP-4 was synthesized by a molecular assembly strategy. G-C3N4 and M-g-C3N4 composite samples were prepared by pyrolytic and co-sintering methods. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy-energy dispersion X-ray spectrometry, and X-ray photoelectron spectroscopy were used to characterize the morphology, structure, element distribution, and element chemical states of the catalysts. Differential scanning calorimetry was used to elevate the thermal catalytic decomposition effect of g-C3N4 and M-g-C3N4 on DAP-4. The results showed that g-C3N4 and M-g-C3N4 have catalytic activity for the thermal decomposition of DAP-4. Among the tested catalysts, Fe-g-C3N4 had the best catalytic activity for the thermal decomposition of DAP-4, as well as advantages over pure g-C3N4 and other M-g-C3N4 catalysts. Especially, Fe-g-C3N4 reduced the peak temperature of DAP-4 by 75.3 °C, increased heat release by 464 J g−1, and decreased activation energy by 55.5 kJ mol−1. Moreover, a possible catalytic mechanism is proposed. This work may offer a new way to promote the application of DAP-4 in the field of solid rocket propellants.