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Enhanced CH4 selectivity in CO2 photocatalytic reduction over carbon quantum dots decorated and oxygen doping g-C3N4
摘要： Graphitic carbon nitride (g-C3N4, CN) exhibits inefficient charge separation, deficient CO2 adsorption and activation sites, and sluggish surface reaction kinetics, which have been recognized as the main barriers to its application in CO2 photocatalytic reduction. In this work, carbon quantum dot (CQD) decoration and oxygen atom doping were applied to CN by a facile one-step hydrothermal method. The incorporated CQDs not only facilitate charge transfer and separation, but also provide alternative CO2 adsorption and activation sites. Further, the oxygen-atom-doped CN (OCN), in which oxygen doping is accompanied by the formation of nitrogen defects, proves to be a sustainable H+ provider by facilitating the water dissociation and oxidation half-reactions. Because of the synergistic effect of the hybridized binary CQDs/OCN addressing the three challenging issues of the CN based materials, the performance of CO2 photocatalytic conversion to CH4 over CQDs/OCN-x (x represents the volume ratio of laboratory-used H2O2 (30 wt.%) in the mixed solution) is dramatically improved by 11 times at least. The hybrid photocatalyst design and mechanism proposed in this work could inspire more rational design and fabrication of effective photocatalysts for CO2 photocatalytic conversion with a high CH4 selectivity.
关键词： carbon quantum dot,photocatalytic,graphitic carbon nitride (g-C3N4),oxygen doping,CO2 reduction
更新于2025-09-12 10:27:22
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Carbon‐Intercalated 0D/2D Hybrid of Hematite Quantum Dots/Graphitic Carbon Nitride Nanosheets as Superior Catalyst for Advanced Oxidation
摘要： Efficient charge separation and sufficiently exposed active sites are important for light-driving Fenton catalysts. 0D/2D hybrids, especially quantum dots (QDs)/nanosheets (NSs), offer a better opportunity for improving photo-Fenton activity due to their high charge mobility and more catalytic sites, which is highly desirable but remains a great challenge. Herein, a 0D hematite quantum dots/2D ultrathin g-C3N4 nanosheets hybrid (Fe2O3 QDs/g-C3N4 NS) is developed via a facile chemical reaction and subsequent low-temperature calcination. As expected, the specially designed 0D/2D structure shows remarkable catalytic performance toward the removal of p-nitrophenol. By virtue of large surface area, adequate active sites, and strong interfacial coupling, the 0D Fe2O3 QDs/2D g-C3N4 nanosheets establish efficient charge transport paths by local in-plane carbon species, expediting the separation and transfer of electron/hole pairs. Simultaneously, highly efficient charge mobility can lead to continuous and fast Fe(III)/Fe(II) conversion, promoting a cooperative effect between the photocatalysis and chemical activation of H2O2. The developed carbon-intercalated 0D/2D hybrid provides a new insight in developing heterogeneous catalysis for a large variety of photoelectronic applications, not limited in photo-Fenton catalysis.
关键词： Fe2O3 QDs,g-C3N4 NS,charge separation,carbon-intercalated 0D/2D hybrid,Fe(III)/Fe(II) conversion
更新于2025-09-11 14:15:04
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Bi4NbO8Cl {001} nanosheets coupled with g-C3N4 as 2D/2D heterojunction for photocatalytic degradation and CO2 reduction
摘要： Photocatalytic activity is largely restricted by insufficient photoabsorption and intense recombination between charge carriers. Here, we first synthesized Bi4NbO8Cl nanosheets with {001} exposing facets by a molten-salt growth method, which shows largely promoted photocatalytic performance for the degradation of tetracycline (TC) and bisphenol A (BPA) in comparison with Bi4NbO8Cl particles obtained by solid-state reaction. The 2D/2D Bi4NbO8Cl/g-C3N4 heterojunction photocatalysts were then fabricated via high-energy ball-milling and post-sintering to realize intimate interfacial interaction. The photocatalytic activity of all the Bi4NbO8Cl/g-C3N4 composites largely enhances compared to Bi4NbO8Cl nanosheets and g-C3N4, also far exceeding the mechanically-mixed Bi4NbO8Cl nanosheets and g-C3N4. The impact of different reaction parameters on the photocatalytic degradation activities was investigated, including catalyst concentration, pH value and TC concentration. In addition, Bi4NbO8Cl/g-C3N4 also presents improved photocatalytic CO2 reduction activity for CO production. The large enhancement on photocatalytic activity of Bi4NbO8Cl/g-C3N4 composites is owing to the synergistic effect of favorable 2D/2D structure and construction of type II heterojunction with intimate interfacial interaction, thus boosting the charge separation. The formation of type II heterojunction was evidenced by selective photo-deposition of Pt and MnOx, which demonstrate that the reductive sites and oxidative sites are on Bi4NbO8Cl nanosheets and g-C3N4, respectively. This work may provide some insights into fabrication of efficient visible-light driven photocatalysts for environmental and energy applications.
关键词： g-C3N4,photodegradation,Bi4NbO8Cl nanosheets,CO2 reduction,heterojunction
更新于2025-09-11 14:15:04
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Constructing g-C3N4 quantum dots modified g-C3N4/GO nanosheet aerogel for UV-Vis-NIR driven highly efficient photocatalytic H2 production
摘要： The development of ultraviolet to near-infrared (UV-Vis-NIR) responsive photocatalysts offers a unique opportunity for the full use of solar energy to solve the energy and the environmental problems. Here, successful preparation of a three-dimensional (3D) porous photocatalyst of graphitic carbon nitride quantum dot (CNQDs) modified g-C3N4/graphene oxide composite aerogel (CNGO/CNQDs) via hydrothermal and vacuum injection method was reported. In this unique ternary 3D photocatalyst, graphene oxide could improve the separation of photogenerated electrons and holes and promote the charge separation, while the aerogel’s 3D network structure provided a rich active site. Simultaneously, due to the appropriate up-conversion performance of the nitrogen carbide quantum dots, CNGO/CNQDs achieved a light response from ultraviolet (UV) to near-infrared (NIR). These properties endow it with a good photocatalytic performance. The hydrogen production efficiency of CNGO/CNQDs reached 1231 mmol h?1, which was 16 times more than that of matrix material. In addition, the apparent quantum yields (AQY) of CNGO/CNQDs at wavelengths of 420 nm and 700 nm were 13% and 0.116%, respectively.
关键词： Photocatalytic,Quantum dots,3D,UV-Vis-NIR driven,g-C3N4
更新于2025-09-11 14:15:04
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Ultrathin WO3 nanosheets modified by g-C3N4 for highly efficient acetone vapor detection
摘要： In this work, ultrathin WO3 nanosheets were prepared by self-assembly approach and their phase and morphology were regulated by changing the heat treatment temperature. Then, g-C3N4 modified WO3 nanosheets sensitive material was fabricated via a facile liquid ultrasonic mixing method. The microstructure, morphology, chemical composition, oxidation state and surface area of WO3 nanosheets and g-C3N4/WO3 nanocomposite were comparatively studied by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). Sensing performances of WO3 nanosheets and g-C3N4/WO3 composite with different g-C3N4 loading amount were investigated with acetone as a target gas. Compared to WO3 nanosheets, the g-C3N4/WO3 gas sensor exhibits good response, excellent selectivity, transient response and trace detection ability to acetone vapor. Effects of g-C3N4 content on gas sensitivity were also investigated. The response (Ra/Rg) of the gas sensor based on 1 wt% g-C3N4/WO3 was 35 toward 100 ppm acetone at 340 °C, which was about 300% higher than the response value of pure WO3 sensor. The sensor also showed a fast response/recovery speed (9 s/3.8 s) and a wide linear detection range (from 0.5 ppm to 500 ppm). These unique sensing properties were attributed to the synergistic effects including the contribution of WO3 ultrathin nanosheets, suitable crystal phase and porous surface, and the sensitization of g-C3N4, which increases the specific surface area and regulates the electrical properties. This work will contribute to the development of new acetone sensors and expand the application of g-C3N4 composite materials.
关键词： g-C3N4 nanosheets,acetone detection,nanocomposites,WO3 nanosheets
更新于2025-09-10 09:29:36
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Bioinspired Synthesis of Carbon Dots/g-C <sub/>3</sub> N <sub/>4</sub> Nanocomposites for Photocatalytic Application
摘要： This study reports a fast and green preparative strategy to synthesize water soluble and fluorescent carbon quantum dots (CQDs) through hydrothermal method by using low cost organic waste of human fingernails as the carbon precursor for the first time. The coupling of CQD with pure carbon nitride (g-C3N4) was further explored to enhance the latter’s performance in photocatalysis of 2,4-dicholorophenol (2,4-DCP), a toxic and recalcitrant compound mostly released from industrial effluent. Such coupling overcame the weakness of pure g-C3N4 in photocatalysis process by broadening its visible light absorption and promoting the charge separation. As a result, the removal rate of CQD/ g-C3N4(10) was up to 71.53%, which was approximately 1.5 times higher than that of pure g-C3N4 under sunlight irradiation. The morphological structure, optical properties and chemical compositions of CQDs/g-C3N4 composites were characterized using various spectroscopic techniques including field emission scanning electron microscopy (FESEM), Energy Dispersive X-Ray (EDX) and Ultraviolet-visible diffuse reflectance spectra (UV-DRS).
关键词： Photocatalysis,Hydrothermal method,Carbon quantum dots,4-dichlorophenol,2,g-C3N4
更新于2025-09-10 09:29:36
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Facile synthesis of rod-like g-C3N4 by decorating Mo2C co-catalyst for enhanced visible-light photocatalytic activity
摘要： Designing and optimizing visible-light-driven photocatalyst with cost-efficiency and high performance is very imperative and highly challenging for photocatalytic hydrogen evolution reaction. Herein, g-C3N4/Mo2C hybrid photocatalyst with one dimensional (1D) heterostructure for highly enhanced photocatalytic H2 generation activity were obtained by a facile two step processing, in which Mo2C nanoparticles were highly dispersed on rod-like g-C3N4 surface. Attributed to the synergistic effect of 1D structure and Mo2C co-catalyst, the resultant g-C3N4/Mo2C sample exhibits an impressive visible-light photocatalytic H2 production rate of up to 507 μmol?h-1?g-1 and quantum efficiencies of 3.74% at 420 nm, which is 9.8 times higher than that of bulk g-C3N4, indicating that decorating Mo2C as co-catalysts on the surface of g-C3N4 leads to the improved visible light absorption, promoted charge separation and enhanced the following H2-evolution rate. Moreover, the mechanism for the photocatalytic activity enhancement was also discussed. This study provides a guide for researchers to design efficient g-C3N4-based hybrid photocatalysts with excellent stability and photocatalytic activity during the photoreaction process.
关键词： Photocatalytic H2 evolution,1D heterostructure,g-C3N4,Mo2C co-catalyst
更新于2025-09-10 09:29:36
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Direct Z-scheme 2D/2D MnIn2S4/g-C3N4 architectures with highly efficient photocatalytic activities towards treatment of pharmaceutical wastewater and hydrogen evolution
摘要： Semiconductor photocatalysis has been regarded as an environmentally friendly technology in wastewater treatment and energy production. Here, a series of direct Z-scheme MnIn2S4/g-C3N4 (MnISCN) photocatalysts without electron mediators were fabricated by a simple hydrothermal route on the basis of in-situ loading of MnIn2S4 (MnIS) nanoflakes on the surface of g-C3N4 (CN) nanosheets. Photocatalytic performances evaluated under visible light irradiation revealed these Z-scheme heterostructured photocatalysts exhibited higher photocatalytic activities than single-component samples. The effect of weight ratio between MnIn2S4 nanoflakes and mesoporous CN nanosheets on photocatalytic activity towards treatment of pharmaceutical wastewater was optimized to achieve highly efficient photocatalytic activities for both degradation of pharmaceutical wastewater and hydrogen generation compared with alone MnIS nanoflakes and isolated mesoporous CN nanosheets. The significant enhancement in photocatalytic activity could be primarily ascribed to the construction of Z-scheme MnISCN architectures, which effectively accelerated the transfer and separation of photogenerated charge carriers via tight interface contacts built among these two components. The recycling experiments for pharmaceutical wastewater treatment revealed the excellent stability of MnISCN nanocomposites. The advantages of highly efficient photocatalytic activity and excellent stability endowed a promising potential for MnISCN nanocomposites to apply in photocatalytic fields.
关键词： pharmaceutical wastewater,g-C3N4,hydrogen evolution,Z-scheme,MnIn2S4
更新于2025-09-10 09:29:36
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Type II heterojunction in hierarchically porous zinc oxide/graphitic carbon nitride microspheres promoting photocatalytic activity
摘要： Graphitic carbon nitride (g-C3N4) is a visible light active semiconductor. However, low conductivity and high recombination rate of photogenerated electrons and holes limit its application in photocatalysis. In this work, we design and synthesize hierarchically porous zinc oxide/ graphitic carbon nitride (ZnO/g-C3N4) microspheres with type-II heterojunction to effectively degrade rhodamine B (RhB) via increasing the charge-separation efficiency. The ultraviolet-visible (UV-Vis) absorption spectra, Mott-Schottky plots and valence band X-ray photoelectron spectroscope confirm the formation of type-II heterojunction between ZnO nanocrystals and g-C3N4 nanosheets. As a result, the 1.5-ZnO/g-C3N4 composite (the mass ratio of zinc acetate dihydrate to g-C3N4 is 1.5) exhibits the highest photocatalytic activity with good stability and higher photocatalytic degradation rate comparing to pure g-C3N4 and pure ZnO. In addition, our results confirm that ?O2- and h+ are the main active species for ZnO/g-C3N4 in degradation of RhB.
关键词： Active species,Heterojunction,Photocatalytic activity,Hierarchically porous structure,ZnO/g-C3N4
更新于2025-09-10 09:29:36
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Preparation of amine functionalized g-C3N4@H/SMOF NCs with visible light photocatalytic characteristic for 4-nitrophenol degradation from aqueous solution
摘要： At ambience temperature, a facile and large-scale sonochemical synthesis route was used to synthesize graphitic carbon nitride@[Ti4C24H39N3O29] metal-organic framework nanocomposites (g-C3N4-X@YTi-MIL125-NH2 NCs, where X and Y stood for the weight percentages of g?C3N4 and the synthesis method of Ti-MIL125-NH2, respectively) having 2-Amino-1,4-benzenedicarboxylic acid (2-ATA) ligand with amine functional free groups. The obtained NCs were characterized by FT-IR, PXRD, FE-SEM, BET, UV-DRS, PL, EIS, and zeta potential. Moreover, g-C3N4-X@YTi-MIL125-NH2 capability to eliminate 4-nitrophenol (4-NP) contaminant from water via visible light illumination was explored. Our synthesized NCs under a facile, green ultrasonic technique (i.e. g-C3N4-30@STi-MIL125-NH2) had a higher percentage of degradation than those from hydrothermal technique (i.e. g-C3N4-30@HTi-MIL125-NH2) with degradation percentages of 75% and 57%, respectively, which resulted in effective mass transfer and separation of photo?generated charge carriers. Additionally, this higher percentage of degradation could be attributed to the larger surface area and unique morphology of the ultrasonically synthesized particles with higher homogeneity and better and non-agglomerated distribution. Furthermore, excellent reusability and stability were observed for g-C3N4-30@STi-MIL125-NH2. We also explored the role of some scavengers in the degradation procedures to investigate the effect of active species. The experimental results were used to describe the suggested mechanism capability for improved photocatalysis.
关键词： Sonochemistry,Photocatalytic degradation,4-Nitrophenol,Metal-organic Framework,g-C3N4@Ti-MIL125-NH2 NCs
更新于2025-09-10 09:29:36