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Phenyl-grafted carbon nitride semiconductor for photocatalytic CO2-reduction and rapid degradation of organic dyes
摘要： Molecular engineering of graphitic carbon nitride (g-C3N4) is achieved by the copolymerization of π-conjugated phenyl urea, melamine, and urea. Integration of aromatic phenyl rings into the heptazine network of g-C3N4 alters its structural, optical and electronic properties. The fusion of polymeric g-C3N4 core with aromatic phenyl groups induces band gap tuning, greatly improves the separation and lifetime of charge-carriers. As a result, CO2 photoreduction experiments conducted by using phenyl grafted g-C3N4 afford methane and formic acid in high yields. Furthermore, a selective model organic pollutant rhodamine B dye is rapidly decomposed under visible light irradiation. This work suggests that pyrolysis of a suitable aromatic π-deficient molecular dopant such as phenyl urea can drastically alter the photo-response of carbon nitride photocatalyst and may enhance its photocatalytic activity. Hence, the present work is expected to be of significant value in sustainable energy production and environmental remediation.
关键词： CO2 photoreduction,photocatalysis,Carbon nitride,Phenyl grafted g-C3N4,dye degradation
更新于2025-09-19 17:15:36
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Cyano-rich mesoporous carbon nitride nanospheres for visible-light-driven photocatalytic degradation of pollutants
摘要： Visible-light-responsive photocatalysis offers exciting opportunities for sustainable environmental pollution control, but the unsatisfactory photoactivity of the existing photocatalysts impedes their practical application. Here, we fabricated a high-activity mesoporous carbon nitride nanosphere (MCNS) photocatalyst by a hard template synthesis method through incomplete polycondensation of the cyanamide precursors during thermal polymerization. The MCNS showed a unique nanosphere structure with a larger specific surface area and possessed more abundant cyano groups than two other graphitic carbon nitride (g-C3N4) materials (i.e., nanosheet and bulk g-C3N4). Experimental results and theoretical calculations indicate important roles of the cyano groups in narrowing the catalyst band gap to favor visible light absorption and accelerating the separation of the electron–hole pairs. With such superior surface properties and improved charge separation efficiency, the MCNS exhibited 14.7 times higher photocatalytic activity for bisphenol A (BPA) degradation than the bulk g-C3N4. The MCNS also showed good stability during repeated use. Therefore, the as-prepared MCNS has great potential for visible-light-responsive photocatalysis in environmental remediation and other photocatalytic applications.
关键词： pollutant degradation,visible-light-driven photocatalysis,bisphenol A,environmental remediation,Cyano-rich mesoporous carbon nitride nanospheres
更新于2025-09-19 17:15:36
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Direct functionalization of methane into ethanol over copper modified polymeric carbon nitride via photocatalysis
摘要： Direct valorization of methane to its alcohol derivative remains a great challenge. Photocatalysis arises as a promising green strategy which could exploit hydroxyl radical (·OH) to accomplish methane activation. However, both the excessive ·OH from direct H2O oxidation and the neglect of methane activation on the material would cause deep mineralization. Here we introduce Cu species into polymeric carbon nitride (PCN), accomplishing photocatalytic anaerobic methane conversion for the first time with an ethanol productivity of 106 μmol gcat?1 h?1. Cu modified PCN could manage generation and in situ decomposition of H2O2 to produce ·OH, of which Cu species are also active sites for methane adsorption and activation. These features avoid excess ·OH for overoxidation and facilitate methane conversion. Moreover, a hypothetic mechanism through a methane-methanol-ethanol pathway is proposed, emphasizing the synergy of Cu species and the adjacent C atom in PCN for obtaining C2 product.
关键词： methane conversion,photocatalysis,polymeric carbon nitride,ethanol production,copper modification
更新于2025-09-19 17:15:36
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Extending the ?-electron conjugation in 2D planar graphitic carbon nitride: Efficient charge separation for overall water splitting
摘要： We report the direct overall pure water splitting by visible light excited graphitic carbon nitride incorporated with conjugated aromatic rings without using sacrificial agents. We fabricated the modified graphitic carbon nitride polymer samples by copolymerization of melamine with 2,4,6-triaminopyrimidine and 1,3,5-triaminobenzene, containing a few-carbon (pyrimidine) to all-carbon (benzene) aromatic rings. Solid state 13C NMR shows that the core molecular skeleton of g-C3N4 remained intact even after the incorporation of benzene and pyrimidine aromatic rings into g-C3N4 chemical structure. Upon substitution of benzene aromatic ring in the place of triazine ring, the optical band gap energy of g-C3N4 is narrowed down from 2.8 eV to 2.1 eV with negative shifts of valence and conduction bands and due to the formation of defects like nitrogen vacancies. The DFT calculations predict that the benzene doped carbon nitride polymer has localized charge densities over valence band maxima and conduction band minima in different parts of heptazine rings, which assist in reducing the recombination rate of the charge carriers. The benzene ring incorporated carbon nitride photoelectrode shows higher photocurrent with lesser charge transfer resistance than the parent g-C3N4 and pyrimidine doped g-C3N4 polymers. This demonstrates the importance of the extended conjugation in g-C3N4 due to the presence of aromatic benzene rings. This is further corroborated by photoluminescence and electron paramagnetic resonance measurements. As a result, the benzene ring incorporated carbon nitride is more active than the pyrimidine ring incorporated carbon nitride for solar water splitting. The benzene ring incorporated carbon nitride polymer directly splits water and generates about 7 μmol h-1 of hydrogen with apparent quantum yield of 1.6% at 450 nm in the absence of sacrificial reagents, achieving turnover number of 1.6.
关键词： turnover number,benzene,DFT calculations,Carbon nitride,apparent quantum yield,charge separation,pyrimidine,water splitting
更新于2025-09-19 17:15:36
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Decoration of carbon dots over hydrogen peroxide treated graphitic carbon nitride: Exceptional photocatalytic performance in removal of different contaminants under visible light
摘要： The development of novel photocatalysts with considerable activity for completely removal of different pollutants from the environment is a dominating goal of modern chemistry. In this study, carbon dots (CDs) were adhered to the graphitic carbon nitride activated by hydrogen peroxide (ag-C3N4) to fabricate photocatalysts with exceptional ability upon visible-light illumination. Interestingly, the BET surface area, visible-light absorption characteristics, and electron-hole separation yield of the pristine g-C3N4 were improved after activation with H2O2 and decoration of CDs. The binary nanocomposite was used for degradation of MB, RhB, fuchsine, and phenol and photoreduction of Cr(VI) under visible light. The nanocomposite exhibited excellent photocatalytic performance with 100% removal of RhB in 60 min, which is almost 34.7 folds as premier as the pristine g-C3N4. Reactive species scavenging measurements displayed that ?O2?, ?OH, and h+ had significant roles for photodegradation of RhB. The possible mechanism was proposed regarding how activation with H2O2 and decoration of CDs improved the photocatalytic performance of g-C3N4. Also, stability of the composite was characterized through cyclic photocatalytic tests.
关键词： Graphitic carbon nitride,g-C3N4/CDs,Hydrogen peroxide treated g-C3N4,Visible-light-active photocatalyst
更新于2025-09-19 17:15:36
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Synergy of NiO quantum dots and temperature on enhanced photocatalytic and thermophoto hydrogen evolution
摘要： Solar-to-hydrogen holds a great sustainable energy solution, in which photocatalysis plays an important role. In this study, a composite photocatalyst with NiO quantum dots (NiO QDs) in graphitic carbon nitride (g-CN) was synthesized and evaluated in photocatalytic (PC) and thermophotocatalytic hydrogen evolution reaction (HER) under visible light. A sample of 9 wt% NiO QDs-g-CN achieved the highest PC-HER rate of 130 μmol·g-1·h-1 at ambient condition, 11 times higher than pristine g-CN. Meanwhile the thermophotocatalytic HER rate reached 260.2 μmol·g-1·h-1 at 55 °C. Photo-illumination led to the formation of C-O bond between g-CN and NiO QDs to bridge photoelectron transport for low HER overpotential barriers and enhanced electrical conductivity. The higher thermophoto-induced HER can be ascribed to the increased electrical conductivity of NiO QDs-g-CN. This work underlines the importance of chemical binding in hetero-structures and quantum confinement effects in QDs-based composites, and it also demonstrates the thermal sensitivity effect in thermophotocatalytic HER process.
关键词： graphitic carbon nitride,thermophotolysis,hydrogen production,Quantum dots,photocatalysis
更新于2025-09-19 17:13:59
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Self-Assembled Protein/Carbon Nitride/Sulfur Hydrogel Photocatalyst For Highly Selective Solar Chemical Production
摘要： Artificial photosynthesis process is a nature inspired process that can convert solar energy to important value added chemicals. Here, we report the synthesis of a self-assembled protein and carbon nitride/sulfur hydrogel (Fmoc-D-PheA/g-C3N4/S) as a visible light active hydrogel photocatalyst for 86.78% reduced nicotinamide adenine dinucleotide (NADH) regeneration and 90.0% L-Glutamate production under solar light irradiation. The present work represents a new benchmark example for NADH regeneration and solar chemical production.
关键词： NADH regeneration,hydrogel photocatalyst,Carbon nitride
更新于2025-09-19 17:13:59
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Supramolecular electrostatic self-assembly of mesoporous thin-walled graphitic carbon nitride microtubes for highly efficient visible-light photocatalytic activities
摘要： For efficient solar energy conversion, the morphology engineering of hollow graphitic carbon nitride (g-C3N4) is one of the promising approachs benefiting from abundant exposed active sites and short photocarrier transport distances, but is difficult to control on account of easy structural collapse. Herein, a facile supramolecular electrostatic self-assembly strategy has been developed for the first time to fabricate mesoporous thin-walled g-C3N4 microtubes (mtw-CNT) with shell thickness of ca. 13 nm. The morphological control of g-C3N4 enhances specific surface area by 12 times, induces stronger optical absorption, widens bandgap by 0.18 eV, improves photocurrent density by 2.5 times, and prolongs lifetimes of charge carriers from bulk to surface, compared with those of bulk g-C3N4. As a consequence, the transformed g-C3N4 exhibits the optimum photocatalytic H2-production rate of 3.99 mmol·h?1·g?1 (λ > 420 nm) with remarkable apparent quantum efficiency of 8.7% (λ = 420 ± 15 nm) and long-term stability. Moreover, mtw-CNT also achieves high photocatalytic CO2-to-CO selectivity of 96% (λ > 420 nm), much better than those on the most previously reported porous g-C3N4 photocatalysts prepared by the conventional hard-templating and soft-templating methods.
关键词： Thin wall,Photocatalysis,Graphitic carbon nitride,H2 production,Mesoporous microtube,CO2 reduction
更新于2025-09-19 17:13:59
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One‐Pot Exfoliation of Graphitic C <sub/>3</sub> N <sub/>4</sub> Quantum Dots for Blue QLEDs by Methylamine Intercalation
摘要： Here, a simplified synthesis of graphitic carbon nitride quantum dots (g-C3N4-QDs) with improved solution and electroluminescent properties using a one-pot methylamine intercalation–stripping method (OMIM) to hydrothermally exfoliate QDs from bulk graphitic carbon nitride (g-C3N4) is presented. The quantum dots synthesized by this method retain the blue photoluminescence with extremely high fluorescent quantum yield (47.0%). As compared to previously reported quantum dots, the g-C3N4-QDs synthesized herein have lower polydispersity and improved solution stability due to high absolute zeta-potential (?41.23 mV), which combine to create a much more tractable material for solution processed thin film fabrication. Spin coating of these QDs yields uniform films with full coverage and low surface roughness ideal for quantum dot light-emitting diode (QLED) fabrication. When incorporated into a functional QLED with OMIM g-C3N4-QDs as the emitting layer, the LED demonstrates ≈60× higher luminance (605 vs 11 Cd m?2) at lower operating voltage (9 vs 21 V), as compared to the previously reported first generation g-C3N4 QLEDs, though further work is needed to improve device stability.
关键词： graphitic carbon nitride,quantum dot light-emitting diodes,metal-free semiconductors,hydrothermal exfoliation
更新于2025-09-19 17:13:59
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A Review on Quantum Dots Modified g-C3N4-Based Photocatalysts with Improved Photocatalytic Activity
摘要： In the 21st century, the development of sustainable energy and advanced technologies to cope with energy shortages and environmental pollution has become vital. Semiconductor photocatalysis is a promising technology that can directly convert solar energy to chemical energy and is extensively used for its environmentally-friendly properties. In the field of photocatalysis, graphitic carbon nitride (g-C3N4) has obtained increasing interest due to its unique physicochemical properties. Therefore, numerous researchers have attempted to integrate quantum dots (QDs) with g-C3N4 to optimize the photocatalytic activity. In this review, recent progress in combining g-C3N4 with QDs for synthesizing new photocatalysts was introduced. The methods of QDs/g-C3N4-based photocatalysts synthesis are summarized. Recent studies assessing the application of photocatalytic performance and mechanism of modification of g-C3N4 with carbon quantum dots (CQDs), graphene quantum dots (GQDs), and g-C3N4 QDs are herein discussed. Lastly, challenges and future perspectives of QDs modified g-C3N4-based photocatalysts in photocatalytic applications are discussed. We hope that this review will provide a valuable overview and insight for the promotion of applications of QDs modified g-C3N4 based-photocatalysts.
关键词： organic pollutant photodegradation,H2 production,graphitic carbon nitride (g-C3N4),photocatalysis,CO2 reduction,quantum dots (QDs)
更新于2025-09-19 17:13:59