Constructing BiOBr/g-C3N4/Bi2O2CO3 Z-scheme photocatalyst with enhanced photocatalytic activity

Journal of Materials Science: Materials in Electronics - In this work, the novel camellia-structured double Z-scheme BiOBr/g-C3N4/Bi2O2CO3 was simply prepared by a hydrothermal method. XRD, FTIR,...     

Fly ash cenospheres as multifunctional supports of g-C3N4/N-TiO2 with enhanced visible-light photocatalytic activity and adsorption

The ternary composites of g-C₃N₄/N-TiO₂/FACs (FAC: Fly Ash Cenospheres) were synthesized by an in-situ hydrolysis method to improve the photocatalytic activity and their stability. When TiO₂ was anchored on FAC, it was easily to be separated from the aqueous solution and could be repeatedly utilized. In the present experiments, the degradation rate remained for more than 68% even after the composite reused for seven times. The band gap of g-C₃N₄/N-TiO₂/FAC was 2.75?eV, which might be owing to the synergistic effect between N-TiO₂ and g-C₃N₄. The composite of g-C₃N₄/N-TiO₂/FAC had an ideal activity of 72.2% under visible light illumination for 180?min. It was about 1.3 times of N-TiO₂/FAC and 3.5 times of g-C₃N₄. The synergistic effect of SiO₂, Fe₂O₃ and TiO₂ components resulted to the improvement of photocatalytic performance.     

苝四羧酸二酰亚胺修饰增强g-C_(3)N_(4)光催化性能EI北大核心CSCD

以3,4,9,10-苝四甲酸二酐和L-天冬氨酸为原料,合成水溶性苝二酰亚胺衍生物N,N′-二(2-丁二酸基)-3,4,9,10-苝四羧酸二酰亚胺(PASP)。采用水热法将PASP接枝在g-C_(3)N_(4)上,制备PASP改性g-C_(3)N_(4)复合光催化剂(g-C_(3)N_(4)-PASP)。通过X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见光漫反射光谱(UV-Vis DRS)和固体荧光光谱等对g-C_(3)N_(4)-PASP的组成、结构、形貌和光学性质等进行表征,考察g-C_(3)N_(4)-PASP对水溶液中模型污染物亚甲基蓝(MB)的光催化降解活性。结果表明:g-C_(3)N_(4)与PASP经水热反应,可通过酰胺键共价结合;相比纯g-C_(3)N_(4),g-C_(3)N_(4)-PASP比表面积显著增大,吸收带边红移至614 nm,同时PASP修饰可促进g-C_(3)N_(4)材料表面光生电子和空穴分离,进而有效提升光催化活性。在可见光(λ>420 nm)照射下,g-C_(3)N_(4)-PASP对MB的降解率60 min内可达99.4%,降解速率常数k约为g-C_(3)N_(4)的2倍。     

High performance magnetically recoverable g-C3N4/Fe3O4/Ag/Ag2SO3 plasmonic photocatalyst for enhanced photocatalytic degradation of water pollutants

The g-C₃N₄/Fe₃O₄/Ag/Ag₂SO₃ nanocomposites have been successfully fabricated by facile refluxing method. The as-obtained products were characterized by XRD, EDX, SEM, TEM, UV–vis DRS, FT–IR, TGA, PL, and VSM techniques. The results suggest that the Ag/Ag₂SO₃ nanoparticles have anchored on the surface of g-C₃N₄/Fe₃O₄ nanocomposite, showing strong absorption in the visible region. The evaluation of photocatalytic activity indicates that for the g-C₃N₄/Fe₃O₄/Ag/Ag₂SO₃ (40%) nanocomposite, the degradation rate constant was 188 × 10^?4 min^?1 for rhodamine B, exceeding those of the g-C₃N₄ (16.0 × 10^?4 min^?1) and g-C₃N₄/Fe₃O₄ (20.2 × 10^?4 min^?1) by factors of 11.7 and 9.3, respectively. The results showed that the nanocomposite prepared by refluxing for 120 min has the superior photocatalytic activity and its activity decreased with rising the calcination temperature. The trapping experiments confirmed that superoxide ion radical was the main active species in the photocatalytic degradation process. Also, it was demonstrated that the magnetic photocatalyst has considerable activity in degradation of one more dye pollutant. Finally, the reusability of the photocatalyst was evaluated by five consecutive catalytic runs. This work may open up new insights into the utilization of magnetically separable nanocomposites and provide new opportunities for facile fabrication of g-C₃N₄-based plasmonic photocatalysts.     

Preparation of visible light responsive g-C3N4/H-TiO2 Z-scheme heterojunction with enhanced photocatalytic activity for RhB degradation

The development of high-efficiency heterojunction with improved photocatalytic property is regarded as a promising way to decontaminate wastewater. In this study, Z-Scheme g-C₃N₄/H-TiO₂ heterojunctions with different proportions were synthesized. The photocatalytic degradation of rhodamine B (RhB) was studied under visible light irradiation. Among them, 10% g-C₃N₄/H-TiO₂ photocatalyst had the best performance, and the degradation rate of RhB was 65% within 120 min. In addition, 10% g-C₃N₄/H-TiO₂ photocatalyst had high stability, and its photocatalytic activity did not decrease significantly after four cycles. Through photocurrent analysis, it is found that the photogenerated carriers have obviously excellent separation and transfer characteristics, which makes the 10% g-C₃N₄/H-TiO₂ photocatalyst have good degradation performance. Electron paramagnetic resonance (ESR) experiments showed that ·OH and ·O₂^? were active radicals during degradation.

     

The pre-acidizing corrosion on the surface of TiO2 enhanced the photocatalytic activity of g-C3N4/TiO2

In this work, g-C₃N₄/TiO₂ nanocatalysts were prepared by high-voltage electrospinning and hydrothermal methods. The surface of the pure TiO₂ nanomaterial was treated by acidification before it was combined with g-C₃N₄.Various characterization methods were used to characterize the prepared photocatalyst. RhB (20 mg/L) was degraded as a target-degradable pollutant, the degradation efficiency of the nanocatalyst was measured under UV–Visible light. The results show that the degradation efficiency of the g-C₃N₄/TiO₂ nanocomposite material that has undergone pre-acidification treatment is much higher than that of the untreated catalyst.

     

Flower-like SnO2/g-C3N4 heterojunctions: The face-to-face contact interface and improved photocatalytic properties

Series of SnO₂/g-C₃N₄ heterojunctions with face-to-face contact have been synthesized by a two-step process. The morphology and photocatalytic property can be adjusted by tailoring the content of g-C₃N₄ in the heterostructures. The heterojunctions present flower-like morphology and vary the size of flower with the increase of the g-C₃N₄ content. The 50% SnO₂/g-C₃N₄ heterojunctions exhibit the best performances for photodegradation of rhodamine B under solar light, which is attributed to the effective interfacial contact between SnO₂ and g-C₃N₄, leading to the increased charge transfer and prolonged charge-hole separation time. Moreover, SnO₂/g-C₃N₄ heterojunctions possess excellent stability after 4 recycling runs, because the face-to-face contact interface provides a large contact area, thus forming a close combination of two phases and guaranteeing effective separation of photogenerated carriers. Furthermore, a possible photocatalytic mechanism is analyzed and it is demonstrated that the hydroxyl radical species play an important role for the photocatalytic activity. This research highlights the promising applications of SnO₂/g-C₃N₄ heterojunctions photocatalysts in the field of water purification and environmental remediation.     

Preparation of a novel composite g-C3N4/TiO2/NiWO4 with enhanced photocatalytic activity toward the degradation of rhodamine B

A novel ternary heterojunction composite photocatalyst g-C₃N₄/TiO₂/NiWO₄ was fabricated using a simple hydrothermal method. The synthesized samples were characterized using X-ray diffraction (XRD), scanning electronic microscopy (SEM), energy-dispersive spectrum (EDS), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis) absorption spectra, photoluminescence (PL) spectra, transient photocurrent responses, and electrochemical impedance spectroscopies (EIS). The results indicated that the composite of g-C₃N₄/TiO₂/NiWO₄ had been successfully synthesized. By constructing a ternary heterojunction, the electron migration rate and light absorption of the material are further improved; the photogenerated electron–hole recombination is inhibited. The ternary composite photocatalyst shows the highest photocatalytic activity for the degradation of rhodamine B (RhB) than that of g-C₃N₄, TiO₂, NiWO₄, and g-C₃N₄/TiO₂ photocatalyst. The degradation efficiency of RhB using g-C₃N₄/TiO₂/NiWO₄ can reach 99% after visible-light irradiation for 40 min. Finally, the migration mechanism of charge carriers in the ternary system has been schematically illustrated by the active species capture experiment. Our research can pave the way for the fabrication of ternary heterojunction composite photocatalyst with high photocatalytic activity for the environmental contaminants treatment.

     

Fabrication of highly efficient g-C3N4/ZnO/Fe2O3 ternary composite with enhanced photocatalytic activity under visible light irradiation

Journal of Materials Science: Materials in Electronics - The development of an efficient and photostable heterostructured photocatalyst has attracted a great deal of attention for the degradation...     

Synthesis of Z-scheme g-C3N4/Gd-doped Bi2WO6 heterojunction with enhanced visible-light photodegradation of organic dyes

Herein, we prepared the g-C₃N₄/Gd-doped Bi₂WO₆ Z-scheme heterojunction (BCN) composites by a simple hydrothermal method. The composites were investigated by SEM (EDX), TEM, XRD, XPS, UV–Vis DRS and PL analysis. The photocatalytic performance of composites was envaulted by degrading methylene blue (MB) under the irradiation of a 300 W mercury lamp. The results demonstrated that coupling g-C₃N₄ and doping Gd ³⁺ effectively enhanced the photocatalytic efficiency of pure Bi₂WO₆. The 92% of MB was degraded within 120 min by optimal 0.15–100 BCN sample, being 1.61 times as that of Bi₂WO₆. The greatly enhanced performance of 0.15–100 BCN was due to the synergistic effect of Gd ³⁺ doping and g-C₃N₄ coupling, which maintained high redox capacity. According to the experiment of capture active species, Z-scheme charge transfer mechanism was also deduced. This study may provide an efficient and green method for the treatment of dyestuff industrial wastewater.

     

0D/2D Z-scheme heterojunctions of g-C3N4 quantum dots/ZnO nanosheets as a highly efficient visible-light photocatalyst

Constructing Z-scheme heterojunctions comprising of constituents with different dimensionality is an effective strategy to spatially separate electron and hole. To fully utilize the synergistic coupling effect of dimensionality, herein, we first immobilize g-C₃N₄ quantum dots (CNQDs) onto ZnO nanosheets with oxygen vacancies (OV-ZnO) to create a 0D/2D hybrid via a facile and cost-effective approach. The CNQDs/OV-ZnO heterojunctions display CNQDs content-dependent performance in visible-light photocatalytic activity. The optimal CNQDs/OV-ZnO heterojunction exhibits high photocatalytic activity for degradation of methyl blue and bisphenol A, where the kinetic constant is 11.4 and 32.5 fold of pure OV-ZnO, respectively. Photoluminescence, electrochemical impedance spectroscopy and photocurrent verify that the photogenerated electron-hole pairs in this 0D/2D Z-scheme heterojunction have been effectively separated. The enhanced photocatalytic activity could be attributed to the synergistic effect of efficient Z-scheme charge separation, highly dispersed 0D CNQDs, coordinating sites of 2D OV-ZnO nanosheets and the strong coupling between them. In addition, the 3D flower-like structure constructed by 2D nanosheets greatly inhibits the leaching and loss of the photocatalyst in the recycling process, and ensures the high recycling ability of CNQDs/OV-ZnO. This work paves the way toward designing novel visible-light 0D/2D photocatalysts in the application of solar energy.     

Superior ultra-thin nanoporous g-C3N4 photocatalyst embedded with S quantum dots: a non-metal Z-scheme visible-light composite

Journal of Materials Science - The replacing and surpassing of some functions of traditional metal-based photocatalysts by low-cost and high-efficiency non-metal semiconductor materials have become...     

Optimized design of visible light-driven g-C3N4 nanorod/Ag3PO4 Z-scheme heterojunction with enhanced interfacial charge separation and photocatalytic activity

Journal of Materials Science: Materials in Electronics - A g-C3N4 nanorod/Ag3PO4 (CN-A) Z-Scheme heterojunction, which can response to visible light, was prepared through a convenient and green...