Mesoporous Graphitic Carbon Nitride Research Articles

Efficient and selective cleavage of lignin C–C bonds under visible light facilitated by the Zn(II)-doped mesoporous graphitic carbon nitride photocatalyst

Despite the promise of photocatalysis for extracting aromatic compounds from renewable lignin feedstocks, the selective cleavage of Cα–Cβ bonds in lignin under mild conditions poses a persistent challenge, primarily due to their elevated dissociation energies and steric hindrance. Herein, an efficient photocatalytic strategy for selectively breaking the Cα–Cβ bonds of lignin with visible-light irradiation and room temperature is proposed, facilitated by the Zn(II)-doped porous graphitic carbon nitride (Zn/CN) photocatalyst. Reduced energy band gap and photoluminescence, along with intensified visible-light absorption and enhanced photocurrent of Zn/CN, contribute to its efficacy in photocatalytic activity. Consequently, the lignin model compound (2-phenoxy-1-phenylethanol) achieves a conversion rate of 99%, demonstrating a notable selectivity of 97 % in specifically breaking the Cα–Cβ bonds. Mechanistic investigations identify that photogenerated holes play a pivotal role during the photocatalytic conversion. Additionally, the activity and selectivity of Zn/CN photocatalyst are further confirmed by the successful photocatalytic conversion of pine kraft lignin, yielding high-value chemicals such as benzoic acid and vanillin. This research proposes an economical, efficient, and facile method for utilizing renewable lignin feedstocks under photocatalysis, thus advancing the production of high-value aromatic compounds.

Facile synthesis of SiOx/C as high-performance anodes for lithium-ion batteries

Despite its high capacity (∼2615 mAh·g−1), silicon oxide (SiOx) suffers from low electrical conductivity and volume expansion during cycling, leading to capacity fading. In this work, a SiOx/C composite was synthesized by magnesium thermal reduction using co-assembled mesoporous SiO2 and graphitic carbon nitride (g-C3N4) as precursors. The SiOx/C composite displays a sheet-like nanostructure with highly dispersed SiOx. The presence of carbon enhances the conductivity and structural stability of the composite, leading to a low charge resistance (94.0 Ω), fast lithium diffusion (DLi+ = 5.15 × 10−14 cm2·s−1), and excellent cycling capability (863 mAh·g−1 after 160 cycles).

C(sp2)–S cross-coupling reactions with nickel, visible light, and mesoporous graphitic carbon nitride

Operationally simple photo-nickel C(sp2)–S cross-coupling with a reusable heterogeneous photocatalyst.

Elucidating the conformation effects within adsorption of natural organic matter on mesoporous graphitic carbon

The conformation effects were frequently reported to affect the adsorption of natural organic matter (NOM), but such a specific mechanism is poorly understood. To address this knowledge gap, based on the adsorption of NOM on mesoporous graphitic carbon nitride (MCN) prepared via a novel pseudo-templating method, the conformation effects were elucidated. The results showed that MCNs nano-architectures with uniform mesopores were successfully fabricated and showed prominent adsorption capacity. The maximum adsorption amounts of MCN-0.5 for fulvic acid (FA) and leonardite humic acid (HA) were 73.61 mgC g−1 and 135.57 mgC g−1, respectively. The adsorptive affinities of components for HA and Elliott soil HA (ESHA) were related to structural condensation; the components with the more coiled conformation exhibited higher affinities because of occupying less active sites and weakening the electrostatic repulsion. Such conformation effects were further established with respect to NOM types and components, as well as solution chemistry. HA and ESHA suffered from variations from the coiled to linear conformations as pH increased, but not the other four types of NOM tested, and particularly the humic-like and territorial humic-like components were critical in such conformational variations. The adsorption of HA and ESHA was affected by pH via both the conformation effects and the interaction mechanism. By contrast, the conformation of six types of NOM was not affected by the common cations (Na+, K+, Mg2+, Ca2+), and these cations impacted NOM adsorption only through the conventional interactions.

Poly(vinylidene fluoride‐hexafluoropropylene)/mesoporous graphitic carbon nitride composite membranes for photocatalytic methylene blue degradation and sensing applications

AbstractIn this work, poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP)/mesoporous graphitic carbon nitride (mpg‐C3N4) composite fiber web have been prepared and characterized for photocatalytic methylene blue (MB) degradation and sensing applications. The electrospinning technique, operating at a flow rate of 1 mL/h and a voltage of 15 kV, was utilized to prepare the composite membranes of PVDF‐HFP with the uniform distribution of the mpg‐C3N4. The composite web demonstrated outstanding photocatalytic activity for the degradation of MB, reaching a quick 68% drop in MB concentration in just 45 min. The composite web furthermore worked as a sensor for MB detection. After MB exposure, the film resistance was increased, suggesting its potential as a chemiresistive sensor. The maximum resistivity of PVDF‐HFP/mpg‐C3N4 composites was found to be 90 Ω·m at 2% concentration of MB. The MB molecules' adsorption on the surface of the composite web and the existence of photocatalytic byproducts on the surface may be responsible for this shift in resistance. This dual functionality highlights the adaptability and potential of the PVDF‐HFP/mpg‐C3N4 composite web as a versatile material for environmental sensing and cleanup. This research presents a comprehensive approach to the synthesis, characterization, and evaluation of such flexible membranes for potential applications as self‐cleaning devices and chemiresistive sensor.Highlights PVDF‐HFP/mpg‐C3N4 composite membranes act as an efficient material for MB degradation (68%) with visible light exposure. mpg‐C3N4 plays the role of active material in degradation. PVDF‐HFP/mpg‐C3N4 composite membrane also act as sensors for MB detection. Composite membrane becomes chemiresistive due to notable resistivity changes with MB concentration.

Mesoporous graphitic carbon nitride for photocatalytic coenzyme regeneration

Efficient regeneration of nicotinamide adenine dinucleotide (NADH) is of great significance for the application of oxidoreductase-catalyzed reactions. Photocatalytic regeneration is advantageous for the utilization of cheap, abundant, and clean solar energy. Graphitic carbon nitride (g-C3N4) has attracted wide attention due to its non-toxicity, wide range of precursors, suitable band gap, and superior chemical and thermal stability. In this work, mesoporous g-C3N4 (MPCN) was prepared using silica with different size as the template. The preparation process of MPCN was optimized and the effect of the template size on the structure and properties of MPCN were investigated. The results demonstrate that the smaller the template size, the larger the specific surface area of MPCN, and thus the better the photocatalytic performance. After optimization, the catalytic activity of MPCN with 7 nm silica as the template (MPCN-7) was 17.4 mM/(g min) and the NADH yield after 40 min was 70.6 %. MPCN-7 was also modified by 3-aminothiophene-2-carbonitrile (ATCN) and polyvinylpyrrolidone (PVP). Under same conditions, the catalytic activity of ATCN-MPCN, PVP-MPCN, and ATCN/PVP-MPCN was upgraded from 10.8 to 49.5, 16.4, 29.2 mM/(g min), respectively. The final yield of NADH rose from 66.9 % (40 min) to 76.3 % (12 min), 72.8 % (25 min) and 82.0 % (15 min).

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

The effect of Ni and Co co-catalysts on the catalytic activity of mesoporous graphitic carbon nitride/black phosphorus/molybdenum disulfide heterojunctions in solar-driven hydrogen evolution

In this work, a ternary heterojunction photocatalyst composed of mesoporous graphitic carbon nitride, black phosphorus, and molybdenum disulfide (m-CN/BP/MoS2) was firstly fabricated for the visible-light-driven hydrogen evolution reaction (HER) via water splitting. The photocatalytic activity of m-CN/BP/MoS2 photocatalyst was further improved by incorporating Ni and Co co-catalysts, denoted as m-CN/BP/MoS2-Y (Y: Ni, Co). The final quaternary nanocomposites were experimentally demonstrated in the form of mixed heterojunctions (type-I, type-II, and Schottky junctions) to manipulate the photogenerated carriers with the aim of reducing their recombination rate and increasing the light-harvesting ability of the pristine components. To find the best combination of different semiconductors in the heterojunction to ensure the highest photocatalytic HER activity, the loading ratio of each component was optimized one-by-one by considering the rate of HER under the same conditions. The photocatalytic HER activity of m-CN/BP/MoS2-Ni (5 wt%) and m-CN/BP/MoS2-Co (0.5 wt%) photocatalysts reached up to 21.668 mmol g−1 and 29.179 mmol g−1 for 8 h in the presence of triethanolamine electron donor under visible light irradiation, which were about 11 and 15 times higher than that of m-CN/BP binary heterojunctions, 4 and 5 times higher than that of m-CN/BP/MoS2 ternary heterojunctions, respectively. Ni or Co co-catalysts enhanced charge separation and thus increasing the rate of H2 evolution owing to their suitable d-band levels. This present study supplies a strategy to design efficient photocatalysts for solar fuel production without using non-noble metal cocatalysts.

Effect of carbon support on the activity of monodisperse Co45Pt55 nanoparticles for oxygen evolution in alkaline media.

Oxygen evolution reaction (OER) represents the efficiency-limiting reaction in water electrolyzers, metal-air batteries, and unitized regenerative fuel cells. To achieve high-efficiency OER in alkaline media, we fabricated three novel electrocatalysts by the assembly of as-prepared Co45Pt55 alloy nanoparticles (NPs) on three different carbon-based support materials: reduced graphene oxide (CoPt/rGO), mesoporous graphitic carbon nitride (CoPt/mpg-CN), and commercial Ketjenblack carbon (CoPt/KB). Voltammetry studies revealed that CoPt/rGO electrocatalyst provided lower OER overpotentials accompanied by higher currents and specific current density values than the other two studied materials. Moreover, CoPt/rGO outperformed commercial CoPt/C electrocatalysts in terms of notably higher specific current densities. Additionally, it was found that CoPt/rGO electrocatalyst activity increases with increasing temperature up to 85°C, as suggested by the increase in the exchange current density. Electrochemical impedance spectroscopy studies of three electrocatalysts in OER revealed similar charge transfer resistance, although CoPt/rGO provided a higher current density. The main issue observed during long-term chronoamperometry and chronopotentiometry studies is the materials' instability under OER polarization conditions, which is still to be tackled in future work.

PLATINUM – MESOPOROUS CARBON NITRIDE NANOCOMPOSITES: SYNTHESIS, CHARACTERIZATION AND CATALYTIC PERFORMANCE IN PHENYLACETYLENE HYDROGENATION

The platinum nanocomposites were synthesized by chemical reduction of H2PtCl6·6H2O in situ with a methanol—water mixture using mesoporous graphitic carbon nitride as a stabilizing matrix and a catalyst support. The textural, morphological, and optical properties of the obtained platinum – mesoporous carbon nitride composites (Pt/mpg-C3N4) were studied. Pt/mpg-C3N4 has been developed as an effective heterogeneous catalyst for the gas and liquid phase hydrogenation of phenylacetylene. An efficient and versatile approach to the modification of platinum with various organic solvents and ligands for the selective hydrogenation of phenylacetylene to styrene in a flow gas-phase process is pre-sented. The addition of pyridine, piperidine, or morpholine to the starting solution of phenylacetylene in hexane provides 95–100% conversion and 90–92% selectivity to styrene. A sharp increase in the selectivity to styrene without substantial changes in conversion is also observed when THF, ethanol, triethylamine, dioxane, or chloroform are used as diluents. The obtained Pt/mpg-C3N4 composites also demonstrated considerable catalytic activity in the selective hydrogenation of phenylacetylene to styrene at low temperatures in the liquid phase

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.

Switchable Perfluoroalkylation of Terminal Alkynes Promoted by Mesoporous Graphitic Carbon Nitride

Switchable Perfluoroalkylation of Terminal Alkynes Promoted by Mesoporous Graphitic Carbon Nitride

Photocatalytic One-Pot Conversion of Aldehydes to Esters and Degradation of Rhodamine B Dye Using Mesoporous Graphitic Carbon Nitride

Photocatalytic One-Pot Conversion of Aldehydes to Esters and Degradation of Rhodamine B Dye Using Mesoporous Graphitic Carbon Nitride

Visible-light-induced mesoporous graphitic carbon nitride-catalyzed trifluoromethylation and perfluoroalkylation of 4-aminocoumarins

A heterogeneous mesoporous graphitic carbon nitride (mpg-C3N4) photocatalytic 3-trifluoromethylation/perfluoroalkylation of 4-aminocoumarins was realized from 4-aminocoumarins and CnF2n+1SO2Na under mild conditions.

Synthesis and electrochemical characterization of mesoporous graphitic carbon nitride for super capacitor applications

Graphitic carbon nitride (g-C3N4), a fascinating polymeric material comprising nitrogen framework, has become a new research focus and has emerged as one of the most promising material in the area of energy storage devices. It has appealing features such as chemical stability, thermal stability and environment friendly properties. However, due to its low surface area, the electrochemical characteristics of bulk g-C3N4 obtained by standard thermal polymerization process are typically below par. This article presents two techniques of synthesising mesoporous g-C3N4 with enhanced porosity and specific surface area as well as higher electrode material conductivity thereby making it suitable for supercapacitor applications.The article outlines the two synthesis techniques of mesoporous g-C3N4 along with their electrochemical properties. The first technique is using a simple one-pot strategy (CN1) and the second one is carbonated beverage assisted hydrothermal method (CN2). In the first method, CN1 thus prepared exhibited a specific capacitance of 114.5F/g at a current density 0.5 A/g with 100 % coulombic efficiency and 90 % retention after 5000 charge and discharge cycles at 5A/g. The operational power was estimated to be 1330.2 W/kg with a specific energy of 1.74 Wh/kg. CN2 obtained by hydrothermal method exhibited a specific capacitance of 150.5F/g at current density 0.5 A/g with>100 % coulombic efficiency and 95 % retention after 5000 charge and discharge cycles at 5A/g. It also exhibited impressive energy density of 3.92 Wh/Kg at power density of 1666 W/Kg. This study reveals that CN2 is a long-lasting material with superior electrochemical properties, a moderate amount of energy and a high operating power compared to CN1 and bulk g-C3N4.

Photocatalytic C-N cross-coupling mediated by heterogeneous nickel-coordinated carbon nitride.

An easy to prepare nickel-coordinated mesoporous graphitic carbon nitride (Ni-mpg-CN) was introduced as a heterogeneous photocatalyst, which efficiently accelerated the photocatalytic C-N cross-coupling of (hetero)aryl bromides and aliphatic amines, delivering the desired monoaminated products in good yields. In addition, the concise synthesis of the pharmaceutical tetracaine was accomplished in the final stage, further highlighting the practical applicability.

Removal of hazardous diethyl phthalate released from plastics using mesoporous graphitic carbon nitride boosted with ferrocene (Fc/g-C3N4) under visible light

The modification of the structure and surface of graphitic carbon nitride (g-C3N4) with transition organo-metallic compounds for photocatalytic applications has been expanded in recent years.

Highly efficient oxidation of aqueous contaminants by mesoporous graphitic carbon nitride supported copper phosphide with dual active sites

Rational design of low-cost and high-efficient non-precious-metal based Fenton-like catalysts has drawn tremendous attention. Mesoporous graphitic carbon nitride (m-CN) supported copper phosphide (Cu3P@m-CN) catalysts were synthesized, and applied in organic oxidation using H2O2 as the oxidizing reagent. Cu3P@m-CN exhibited excellent stability and high activities toward various organic pollutants over a wide pH range. Removal efficiency of pollutants depends on catalyst type and loading, main operating parameters (pollutant concentration, H2O2 dosage, reaction temperature and solution pH) and different water matrices. Quenching, electron paramagnetic resonance and fluorescence tests confirm that HO∙ and O2·-/HO2· serve as the main active species for pollutant degradation. The abundant cation (Cuδ+) and anion (Pδ−) as the dual active sites in Cu3P synergistically activate H2O2. Cuδ+ can activate H2O2 and promote the Cu2+/Cu+ cycle by electron transfer. Pδ- has the ability to donate electrons, which can also activate H2O2 and regenerate Cu+ from Cu2+. Porous m-CN materials could not only improve the dispersibility of Cu3P nanoparticles, but also effectively promote electron transfer, thus enhancing the catalytic performance, superior to other traditional supports. Consequently, the work demonstrated that the combination of Cu3P and m-CN was a feasible strategy for preparation of effective catalysts toward mineralization of organic pollutants.

Mesoporous Graphitic Carbon Nitride Photocatalyzed Switchable Divergent Perfluoroalkylation of Terminal Alkynes.

An efficient and eco-friendly heterogeneous photocatalytic system for the switchable divergent perfluoroalkylation of terminal alkynes has been developed by employing mesoporous graphitic carbon nitride (mpg-CN) as a recyclable, nontoxic, and heavy-metal-free photocatalyst. Regulating the reaction solvents allowed libraries of perfluoroalkylated alkynes, alkenes, and alkenyl iodides to be synthesized in good-to-high yields. Furthermore, mpg-CN is applicable for gram-scale photosynthesis and could be readily recovered for successive reuses.

Catalytic dehydrogenation of natural terpenes via CuPd alloy nanoparticles generated on mesoporous graphitic carbon nitride

A facile wet‐chemical protocol for the synthesis of bimetallic CuPd alloy nanoparticles (NPs) anchored on mesoporous graphitic carbon nitride (m‐gCN), serving as both stabilizer and support material, was presented herein. The presented protocol allowed to synthesize nearly monodisperse CuPd alloy NPs with an average particle size of 3.9 ± 0.9 nm without use of any additional surfactants and to prepare CuPd/m‐gCN nanocatalysts with different Cu/Pd compositions (Cu25Pd75/m‐gCN, Cu35Pd65/m‐gCN, Cu16Pd74/m‐gCN, Cu32Pd68/m‐gCN, Cu10Pd90/m‐gCN, and Cu50Pd50/m‐gCN). After the detailed characterization of CuPd/m‐gCN nanocatalysts, they were utilized as catalysts in the dehydrogenation of terpenes. Among all tested nanocatalysts, Cu50Pd50/m‐gCN showed the highest activity in terms of the product yields within the same reaction time. Various parameters influencing the catalytic activity of Cu50Pd50/m‐gCN were studied using himachalene as a model substrate and the optimum conditions were determined. Under the optimized reaction conditions, the catalytic application of Cu50Pd50/m‐gCN nanocatalysts was extended to nine different terpenes and the corresponding products were obtained in high conversion yields (>90%) under mild conditions. A reusability test showed that Cu50Pd50/m‐gCN nanocatalysts can be re‐used up to four cycles without significant loss in their initial activity.