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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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The preparation of spherical mesoporous g-C3N4 with highly improved photocatalytic performance for H2 production and rhodamine B degradation
摘要： Spherical mesoporous graphitic carbon nitride (g-C3N4) was successfully prepared through spherical mesoporous silica as sacrificial templates, and analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analyzer, N2 adsorption-desorption isotherm, BET, UV-vis diffuse reflectance spectra and photoluminescence spectra. Experimental results indicated that as-prepared g-C3N4 exhibited spherical morphology with high surface area due to the introduced porous structure, which made the as-prepared g-C3N4 possess much higher activity than the bulk g-C3N4 for producing H2 and decomposing rhodamine B (RhB) under visible light, and it also kept excellent recycling activity. Hence, this investigation provided a simple strategy for the fabrication of porous special morphology graphitic carbon nitride with excellent photocatalytic activity.
关键词： Visible light,spherical mesoporous g-C3N4,Photocatalyst,Photocatalytic activity
更新于2025-09-19 17:15:36
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Hierarchical CoFe-Layered double hydroxide and g-C3N4 heterostructures with enhanced bifunctional photo/ electrocatalytic activity towards overall water splitting
摘要： To achieve sustainable and clean energy for the hydrogen economy, developing efficient earth-abundant and non-noble transition metal photo/electrocatalysts toward overall water splitting is highly desirable. In this work, layered double hydroxide (LDH)@g-C3N4 composites with hierarchical flower-like micro/nanosheets and high surface area have been synthesized by a solvothermal method. HRTEM images exhibit that the surface of g-C3N4 nanosheets is highly orientation with the main exposure of (002) plane. Compared with the pristine CoFe-LDH, the hierarchical nanocomposite presents an excellent and stable electrocatalytic performance in 1.0 M KOH, with a small Tafel slope of 58 mV/dec and an overpotential of about 275 mV at a current density of 10 mA/cm2. Simultaneously, CoFe-LDH@g-C3N4 exhibits an exceptional performance for the HER in 1.0 M KOH electrolyte, with the overpotential of 417 mV at a current density of 10 mA/cm2 and a small Tafel slope of 77 mV/dec. Therefore, this work not only accomplishes improved catalytic activity of the CoFe-LDH by the introduction of g-C3N4 nanosheets, but also provides an insight into the correlation between the hierarchical flower-like morphologies and photo/electrochemical catalytic activity for overall water splitting.
关键词： bifunctional activity,photo/electrocatalysts,hierarchical CoFe-LDH@g-C3N4,solvothermal method,overall water splitting
更新于2025-09-19 17:15:36
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Dual Functional S-Doped g-C3N4 Pinhole Porous Nanosheets for Selective Fluorescence Sensing of Ag+ and Visible-Light Photocatalysis of Dyes
摘要： This study explores the facile, template-free synthesis of S-doped g-C3N4 pinhole nanosheets (SCNPNS) with porous structure for fluorescence sensing of Ag+ ions and visible-light photocatalysis of dyes. As-synthesized SCNPNS samples were characterized by various analytical tools such as XRD, FT-IR, TEM, BET, XPS, and UV–vis spectroscopy. At optimal conditions, the detection linear range for Ag+ was found to be from 0 to 1000 nM, showing the limit of detection (LOD) of 57 nM. The SCNPNS exhibited highly sensitive and selective detection of Ag+ due to a significant fluorescence quenching via photo-induced electron transfer through Ag+–SCNPNS complex. Moreover, the SCNPNS exhibited 90% degradation for cationic methylene blue (MB) dye within 180 min under visible light. The enhanced photocatalytic activity of the SCNPNS was attributed to its negative zeta potential for electrostatic interaction with cationic dyes, and the pinhole porous structure can provide more active sites which can induce faster transport of the charge carrier over the surface. Our SCNPNS is proposed as an environmental safety tool due to several advantages, such as low cost, facile preparation, selective recognition of Ag+ ions, and efficient photocatalytic degradation of cationic dyes under visible light.
关键词： cationic dyes,pinhole porous nanosheet,photocatalytic degradation,visible light,Ag+ ions,S-doped g-C3N4,fluorescence sensing
更新于2025-09-19 17:15:36
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Surface plasma Ag-decorated single-crystalline TiO2?x(B) nanorod/defect-rich g-C3N4 nanosheet ternary superstructure 3D heterojunctions as enhanced visible-light-driven photocatalyst
摘要： Ag-TiO2-x(B)/g-C3N4 ternary heterojunctions photocatalysts are fabricated by hydrothermal-calcination, photo-deposition procedure, and followed by in-situ solid-state chemical reduction procedure. As-obtained photocatalysts are consisted with heterojunctions between 2D g-C3N4 sheets and 1D TiO2(B) single-crystalline nanorods. The band gap of Ag-TiO2-x(B)/g-C3N4 ternary heterojunctions photocatalysts is reduced to ~2.23 eV due to plasma Ag and surface engineering. Under visible light irradiation, it has an optimal photocatalytic property for the reduction of Cr6+ (95%) and degradation of NH4+ (93%). The apparent reaction rate constants (k) of ternary heterojunctions photocatalysts for NH4+ and Cr6+ are 25 and 12 folds higher than that of original TiO2(B). Furthermore, Ag-TiO2-x(B)/g-C3N4 also has excellent hydrogen production efficiency, which is up to 410 mmol h-1 g-1. This enhancement can be attributed to the unique heterojunction formed by 1D single-crystalline TiO2(B) nanorods and 2D g-C3N4 sheets, surface plasma resonance effect of plasma Ag nanoparticle, and surface engineering. A possible photocatalytic mechanism is also proposed by analysizing the XPS valence-band spectra and the Mott-Schottky.
关键词： Surface engineering,g-C3N4 sheet,Visible-light-driven photocatalysis,Single-crystalline TiO2(B) nanorod,Heterojunction
更新于2025-09-19 17:15:36
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Upgrading the photocatalytic achievement of g-C3N4 nanosheets along decoration with Ag@TiO2 nanospheres for the preparation of vitamin B3
摘要： In this investigation, synthesis of ternary heterojunctions made of g-C3N4 sheets decorated with Ag@TiO2 nanospheres was successfully achieved. The reaction was initially started by combustion routine adopting silica of mesoporous type as a template to fabricate mesoporous C3N4 of graphite-like structure. After that, g-C3N4 nanosheets were decorated with TiO2 nanospheres and then TiO2 nanospheres were doped with Ag. Ag@TiO2/g-C3N4 ternary heterojunctions having 140 m2 g?1 specific surface area were produced. The resultant heterojunctions acquired a limited bandgap (2.26 eV) in addition to 3.4 nm pore size. The resultant Ag@TiO2/g-C3N4 nanocomposites were tested applying the photo-catalytic preparation of vitamin B3. It was observed that vitamin B3 could be synthesized adopting mesoporous Ag@TiO2/g-C3N4 ternary heterojunctions with a higher rate (33 times) than that when pristine TiO2 was adopted. The greater photo-catalytic action of the synthesized heterojunction might be correlated to the favorable Vis light absorption as well as the large separation between es and positive holes produced from inclusion of Ti3+ self-doping. In addition, huge amount of active sites was offered owing to the mesoporous network nature of the resultant heterojunctions. Finally, the dopant Ag nanoparticles positively supported the photocatalytic activity by its surface plasma resonance effect.
关键词： Ag@TiO2/g-C3N4 ternary heterojunctions,Vitamin B3,Visible photocatalyst
更新于2025-09-19 17:15:36
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Soluble g-C3N4 nanosheets: facile synthesis and application in photocatalytic hydrogen evolution
摘要： The high dispersibility and solubility are highly required for the potential applications and development of well-known g-C3N4 material. In this study, a facile hydrothermal treatment and the following vacuum freezing-drying process was developed to synthesize the g-C3N4 nanosheets (ca. 5 nm) with excellent dispersibility and solubility in aqueous solutions. It was found that the melem structures with many hydrophilic groups (-NH2, -OH and -C=O) were formed on the g-C3N4 nanosheet surface, resulting in the formation of soluble g-C3N4 (SCN) nanosheets. Moreover, the SCN nanosheets can be worked as the effective modifier to greatly increase the H2-production performance of conventional g-C3N4 photocatalyst (the resultant sample was referred to SCN/g-C3N4). Photocatalytic results revealed that the SCN/g-C3N4 sample exhibited a remarkably higher H2-production performance than the pure g-C3N4 by a factor of ca. 2. The improved H2-production rate of SCN/g-C3N4 photocatalysts could be primarily ascribed to the introduction of hydrophilic groups, which not only remarkably enhances the dispersibility and hydrophilicity of SCN/g-C3N4, but also work as the interfacial active sites to accelerate the H+-reduction reaction and the rapid formation of H2. The present soluble g-C3N4 nanosheets provide potential various applications in environmental protection and energy conversion fields.
关键词： photocatalysis,H2-evolution,solubility,g-C3N4 nanosheets,dispersibility
更新于2025-09-19 17:15:36
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Interfacial coupling effects in g-C3N4/SrTiO3 nanocomposites with enhanced H2 evolution under visible light irradiation
摘要： The g-C3N4/SrTiO3 nanocomposite is an important material in photocatalysis, but little attention has been paid to their interfacial interaction in photocatalytic reaction. Herein, we prepare the g-C3N4/SrTiO3 nanocomposites via a two-step mechanically milling and calcination process. The composite exhibited the highest H2 evolution activity superior to that of the pure g-C3N4 and SrTiO3 in the visible light. The results of UV-vis DRS, PL and photoelectrochemical measurements demonstrated that g-C3N4/SrTiO3 exhibited more visible light adsorption and faster photo-generated charge transfer. Furthermore, with the help of a strong built-in electric field presenting in the g-C3N4/SrTiO3 interface, the photo-generated electrons flow to the SrTiO3 from g-C3N4, leading to the highly-efficient electron separation and more H2O molecules photo-reduction to H2. This work explicates the significant role of built-in electric field in H2 evolution on g-C3N4/SrTiO3 photocatalyst.
关键词： built-in electric field,g-C3N4,visible light,H2 evolution,SrTiO3
更新于2025-09-19 17:15:36
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Construction of two dimensional Sr2Ta2O7/S-doped g-C3N4 nanocomposites with Pt cocatalyst for enhanced visible light photocatalytic performance
摘要： Visible light-driven photocatalytic hydrogen production has been deemed a potential means to solve the increasingly serious energy shortage problem. Herein, two dimensional (2D) Sr2Ta2O7/S-doped g-C3N4 nanocomposites that applied in photocatalytic water reduction were fabricated through thermal condensation of thiourea with hydrothermal-prepared Sr2Ta2O7. The resulted Sr2Ta2O7/S-doped g-C3N4 nanocomposite exhibited enhanced hydrogen evolution rate (11.36 μmol g?1 h?1) under visible light irradiation, which is about 3.5 times higher than that of pure S-doped g-C3N4. In light of the UV–vis diffuse reflectance spectroscopy, Mott-Schottky curve and photoluminescence spectra, the enhanced photocatalytic performance could be mainly attributed to the conduction band difference between Sr2Ta2O7 and S-doped g-C3N4. In addition, transient photoluminescence spectra, electrochemical impedance spectra and photocurrent responses proved that the presence of Pt cocatalyst also plays an important role in facilitates the transport of photoexcited electron-hole pairs, subsequently promoting the photocatalytic performance.
关键词： Sr2Ta2O7,Nanocomposite,g-C3N4,Photocatalytic water splitting
更新于2025-09-19 17:15:36
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Enhanced Visible-light-driven Photoelectrochemical and Photocatalytic Performance of Au-SnO2 quantum dot-anchored g-C3N4 Nanosheets
摘要： A novel g-C3N4/Au-SnO2 quantum dot (g-CN/Au-SQD) ternary nanocomposite was fabricated via a three-step approach for the degradation of the organic pollutant rhodamine B (RhB), and photoelectrochemical (PEC) water splitting upon visible light illumination. Au-SQDs were prepared via a one-pot chemical reduction method, and g-CN was synthesized via the thermal polymerization of urea at 550 ℃. The g-CN/Au-SQD ternary nanocomposite was prepared via sonication, stirring, and finally annealing. This approach was effective for the mixing and dispersion of Au-SQDs over the entire surface of the two-dimensional (2D) g-CN nanosheets. Morphological studies revealed that the Au-SQDs were well-distributed over the nanolayers of the g-CN. The light-capturing ability was improved and optimized with the loading of different amounts of Au-SQDs. The bandgap was tuned from 2.85 eV (g-CN) to 2.58 eV (g-CN/Au-SQD). Photoluminescence analysis revealed the inhibited nature of recombination of electrons and holes in the ternary nanocomposites. Optimization yielded CNAS-20, which exhibited the best photocatalytic performance within 40 min for the degradation of the pollutant RhB. Furthermore, the CNAS-20 photoelectrode showed lower charge-transfer resistance than the other prepared samples, which was favorable for PEC water splitting. The CNAS-20 photoelectrode exhibited a significant photocurrent, which was ~3.83 times greater than that of pure g-CN. Thus, this unique design incorporates a 2D g-CN and plasmonic Au metal nanoparticles for the generation of photoexcited electrons, and SQDs receive these photogenerated electrons to increase the leave-taking of electron and holes to enhance the photocatalytic and PEC activities.
关键词： Quantum dots,Photocatalysis,g-C3N4,Au-SnO2,Surface plasmon resonance
更新于2025-09-19 17:13:59