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Carbon Vacancies in a Melon Polymeric Matrix Promote Photocatalytic Carbon Dioxide Conversion
摘要： Photosynthetic conversion CO2 into fuel and chemicals is a promising but challenging technology. The bottleneck of this reaction lies in the activation of CO2, owing to the chemical inertness of linear CO2. Herein, we present a defect engineering methodology to construct CO2 activation sites by implanting carbon vacancies (CVs) on the melon polymer (MP) matrix. Positron annihilation spectroscopy confirms the location and density of the CVs in the MP skeleton. transform spectroscopy and density functional theory (DFT) study reveals that the CVs can function as active sites for CO2 activation, while stabilizing COOH* intermediates, thereby boosting the reaction kinetics. As a result, the modified MP-TAP-CVs display a 45-fold improvement in CO2-to-CO activity over the pristine MP. The apparent quantum efficiency of the MP-TAP-CVs achieves 4.8 % at 420 nm, which exceeds most of the heterogeneous reduction of CO2 under visible light. This study will shed new light on the design of high-efficiency polymer semiconductors for CO2 conversion.
关键词： Carbon nitride,Photocatalysis,CO2 reduction,Carbon vacancy
更新于2025-09-10 09:29:36
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One step to prepare CNTs modified porous g-C3N4 with excellent visible-light photocatalytic performance
摘要： A kind of carbon nanotubes (CNTs) modified porous graphitic carbon nitride (CNTs/pg-C3N4) photocatalyst was successfully synthesized via one step thermal polycondensation and completely measured by some instruments, such as XRD, FTIR, TEM, BET, DRS, PL, etc. And the relevant experimental data indicated that loaded CNTs could be beneficial to the photoinduced charges transfer, facilitating photoinduced charge separation rate. Meanwhile, surface area and visible light adsorption of CNTs/pg-C3N4 photocatalyst could be increased and improved. These synergetic effects resulted in the as-synthesized CNTs/pg-C3N4 photocatalyst exhibiting better visible-light-induced photocatalytic performance for organic pollutant degradation and the product of clean energy than bulk g-C3N4, pg-C3N4 and CNTs modified bulk g-C3N4, and excellent stable photocatalytic performance was also observed after several recycling experiments. Finally, a reasonable improved photocatalytic reaction mechanism for CNTs/pg-C3N4 photocatalyst is presented.
关键词： Porous graphitic carbon nitride,Photocatalytic performance,Carbon nanotubes,Photocatalyst,Visible-light
更新于2025-09-10 09:29:36
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Visible photodegradation of ibuprofen and 2,4-D in simulated waste water using sustainable metal free-hybrids based on carbon nitride and biochar
摘要： Rational designing of metal-free carbon nitride based photocatalysts can lead to an excellent optical response and a higher photocatalytic activity driven by visible and solar light. This combines green photocatalytic technology with greener materials prepared by facile approaches for environmental remediation. Herein we report utilization of star photocatalyst g-C3N4 (CN) to form highly efficient hetero-assemblies along with acidified g-C3N4 (ACN), polyaniline (PANI), reduced graphene oxide (RGO) and biochar. By use of these organic semiconductors we synthesize g-C3N4/ACN/RGO@Biochar (GARB), g-C3N4/PANI/RGO@Biochar (GPRB) and ACN/PANI/RGO@Biochar (APRB) nano-assemblies with different optical response and band edge positions for a better charge flow and reduced recombination of carriers. These synthesized catalysts were used for visible light powered degradation of 2,4-Dichlorophenoxy acetic acid (2,4-D) and ibuprofen (IBN). APRB performs the best and degrades 99.7% and 98.4% of 2,4-D and IBN (20 mg L?1) under Xe lamp exposure in 50 min and retention of high activity in natural sunlight. Optical analysis, photoelectrochemical response and radical quenching studies show both hydroxyl and superoxide radical anions as major reactive species and a Z-scheme photocatalytic mechanism. RGO acts as an electron mediator and protects higher positioned bands of PANI and ACN in APRB for a remarkable photocatalytic activity for a metal free material. The degradation pathway was analyzed by LC-MS analysis and 42% and 40% total organic carbon was removed in 2 h for 2,4-D and IBN degradation respectively. The toxicity of degraded products was analyzed by analyzing viability of human peripheral blood cells with retaining of 99.1% cells.
关键词： Water treatment,Carbon nitride,Nano-assemblies,Environmental detoxification,Biochar: pharmaceutical effluents,Photocatalysis
更新于2025-09-10 09:29:36
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Tunable Type I and II heterojunction of CoOx nanoparticles confined in g-C3N4 nanotubes for photocatalytic hydrogen production
摘要： This work reports tunable heterojunction architectures of cobalt oxides (CoOx) nanoparticles confined on well-arrayed graphitic carbon nitride nanotubes (C3N4 NTs) by using a facile one-pot method but under different annealing atmospheres. A Type II heterojunction of cobalt monoxide nanoparticles (CoO NPs)/C3N4 NTs was obtained after annealing under vacuum, and fine CoO NPs less than 8 nm in size were homogeneously anchored on the surface of C3N4 NTs. A Type I heterojunction of tricobalt tetraoxide (Co3O4)/C3N4 NTs were formed under air condition, and Co3O4 NPs in the size range of 20 to 80 nm were aggregated on the surface. The photocatalytic activities of these two heterojunctions were evaluated with hydrogen production from water splitting. The strategically developed CoO/C3N4 NTs with a 7 wt. % CoO shows the highest H2 yield under visible light irradiation and the best stability among the photocatalysts studied in this work. Comprehensive characterization results reveal that the superior performance of CoO/C3N4 NTs may be attributed to the uniformly distributed smaller nanoparticles on the well-arrayed nanotubes, the longer lifetime of excited electrons, the faster charge transfer and the stronger electronic interaction between the heterojunctions. Our Kelvin probe force microscopy results firmly verify that the CoO/C3N4 NT and Co3O4/C3N4 NT nanocomposites form a Type II and Type I heterojunction, respectively, and charge transfer pathways and reaction mechanisms are therefore established.
关键词： hydrogen production,carbon nitride nanotubes,tricobalt tetraoxide,Heterojunction architectures,cobalt monoxide
更新于2025-09-10 09:29:36
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A true oxygen-linked heptazine based polymer for efficient hydrogen evolution
摘要： O-doped/functional g-CN polymers are promising material which has been reported to modify inherent electronic structure and light harvest ability of the g-C3N4 based photocatalysts. However, the doping position and concentration of hetero atom remains ill-defined although enhanced photocatalytic activity of modified g-CN photocatalysts has been reported. Herein, a facile two step procedure to synthesize heptazine polymer with defined O-atom position in polymer structure is presented. Cyameluric acid, a member of cyamelurine family upon polycondensation under inert atmosphere ensures the insertion of O-atom at bridge position between heptazine units in growing polymer. The developed polymer OLHP (oxygen linked heptazine polymer) attains high hydrogen production efficiency likely due to high O-content and efficient charge separation evident from PL spectra compared to g-CN. This heptazine based precursor design also eliminates the possibility of presence of triazine based moiety defects in g-C3N4 polymers.
关键词： Water splitting,Heterogeneous photocatalysis,Cyameluric acid,Heptazine,carbon nitride
更新于2025-09-10 09:29:36
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Photodegradation of fluazaindolizine in aqueous solution with graphitic carbon nitride nanosheets under simulated sunlight illumination
摘要： The photodegradation of fluazaindolizine (FZDL) under simulated sunlight irradiation was accelerated by the catalysis of graphitic carbon nitride (g-C3N4). Under optimum conditions, such as 5 mg of amount and dispersion, the photodegradation half-life was dramatically enhanced to 2.7 h. More importantly, the pathway of degradation by g-C3N4 was different from both direct photolysis and the catalysis by titanium oxide, with particular negative ions of m/z 221 and 195, corresponding to the cleavage of sulfamide bond and the ring opening of imidazole, respectively. In addition, hydroxyl and superoxide radicals played important roles in photodegradation. The results enriched not only the study of FZDL photodegradation but also the application of g-C3N4. It also suggested the possibility of the water purification by photodegradation for pesticide removal in real life.
关键词： Advanced oxidation processes,Transformation products,Fluazaindolizine,Mass Spectrometery,Photodegradation,Graphitic carbon nitride
更新于2025-09-10 09:29:36
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Dramatically enhanced photoelectrochemical properties and transformed p/n type of g-C3N4 caused by K and I co-doping
摘要： Graphitic carbon nitride (g-C3N4) usually shows amphoteric property in a neutral solution. In this work, a K&I co-doped g-C3N4 is prepared by simply sintering the mixture of dicyandiamine, KI and I2. The K&I co-doping modulates the band structure of g-C3N4 with pulling the Fermi level toward its conduction band minimum. The obtained K&I co-doped g-C3N4 (K&I-C3N4) generates positive photocurrents over the whole investigated potential range, exhibiting a typical n-type semiconductor characteristic. Therefore, the K&I co-doping transforms the g-C3N4 from amphoteric to n-type semiconductor. Also, the prepared K&I-C3N4 shows widened light absorption range and enhanced separation efficiency of the photogenerated charge carriers, which results in the dramatically enhanced photoelectrochemical performance.
关键词： Photoelectrochemical performance,K&I co-doping,Fermi level,p/n type,Graphitic carbon nitride
更新于2025-09-10 09:29:36
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Cobalt oxide loaded graphitic carbon nitride as adsorptive photocatalyst for tetracycline removal from aqueous solution
摘要： The treatment of antibiotic-containing wastewater is of great importance due to the potential threats of antibiotics to human and the ecosystem. We reported the preparation of cobalt oxide loaded graphitic carbon nitride (CoO/g-C3N4) by an impregnation-calcination method for tetracycline (TC) removal from aqueous solution. The developed CoO/g-C3N4 exhibited high adsorption capacity and fast adsorption kinetic for TC due to the complexation of TC with surface loaded CoO. In particular, 7%CoO/g-C3N4-3 sample presented a maximum TC adsorption capacity of 391.4 mg g-1. It was found that Langmuir and pseudo-second order kinetic models fitted TC adsorption process well. Further photocatalytic studies showed that CoO loaded g-C3N4 was active for TC photodegradation, although the photocatalytic reaction rate constant was lower than that of native g-C3N4. CoO nanoparticles loading on g-C3N4 played the major role of adsorption sites rather than cocatalyst for photocatalysis. We believe that the developed CoO/g-C3N4 could be a potential adsorptive photocatalyst for antibiotic pollutants removal from wastewater.
关键词： Graphitic carbon nitride,antibiotic,photocatalysis,adsorption,cobalt oxide
更新于2025-09-10 09:29:36
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Construction of acetaldehyde-modified g-C3N4 ultrathin nanosheets via ethylene glycol-assisted liquid exfoliation for selective fluorescence sensing of Ag+
摘要： We successfully prepared acetaldehyde-modified g-C3N4 ultrathin nanosheets (ACNNSs) by a simple ethylene glycol-assisted liquid exfoliation method. The introduction of acetaldehyde regulated the surface energy of g-C3N4 to better match with that of water, which improved the exfoliation efficiency. Moreover, the acetaldehyde introduces defects into the g-C3N4 structure, which can act as excitation energy traps and cause considerable variation in the fluorescence emission. Benefiting from the stable photoluminescence (PL) emission, good water solubility and biocompatibility, the obtained ACNNSs showed a selective fluorescent response to Ag+ both in aqueous solution and living cells. The strong absorption and intimate contact with Ag+, and its appropriate redox potential of ACNNSs contributed to this excellent fluorescent response. A simple and environmental friendly approach was proposed to simultaneously achieve modification and exfoliation of g-C3N4 in aqueous solution. These findings might lead to wider applications of carbon-based nanomaterials as active materials for fluorescence detection in the environment.
关键词： Graphitic carbon nitride nanosheets,Living-cell imaging,Glycol-assisted exfoliation,Fluorescent sensor,Acetaldehyde-modified,Ag+
更新于2025-09-10 09:29:36
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Nanoscale Materials in Water Purification || Photocatalysis of Graphene and Carbon Nitride-Based Functional Carbon Quantum Dots
摘要： Day by day, global energy demands increase due to the rapid consumption of depleting fossil fuels and environmental pollution. This has led to the search for materials capable of both energy conversion and elimination of environmental pollutants through the aid of renewable solar energy. This is a promising approach for meeting future energy requirements and eliminating environmental pollutants. In this pursuit, semiconductor photocatalysts have immense potential for solving both energy and environmental issues. To date, numerous semiconductor materials have been explored, including those of metal oxides, chalcogenides, borates, titanates, tungstates, vanadates, zirconates, oxyhalides, and metal-based interstitial compounds. However, the majority of these suffer from limitations such as complex synthesis procedures, limited light absorption range due to their wide band gap, high cost, and toxicity-related issues. Over the past decade, carbon-based nanomaterials have gained attention in the field of photocatalysis. Many recent articles have placed emphasis upon metal-free carbon-based photocatalytic systems for degradation of organic pollutants and hydrogen production from water splitting. The prime merit of these nanomaterials is that they originate from naturally abundant constituent elements such as carbon, nitrogen, and oxygen, making them more economical than their metal-based counterparts. Most reported carbon-based photocatalysts have tunable band gap energies, enhancing their optical absorption range. Band gap energy can be tuned by varying synthesis conditions and precursors, resulting in the formation of nanomaterials with different morphologies. The preparation procedures for most carbon-based nanomaterials are less complex than those of metal-based materials.
关键词： water splitting,energy conversion,semiconductor photocatalysts,graphene,carbon nitride,quantum dots,carbon-based nanomaterials,hydrogen production,solar energy,environmental pollutants,photocatalysis
更新于2025-09-09 09:28:46