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.     

类石墨氮化碳/伊利石复合材料的制备及其可见光催化性能

以伊利石为载体、双氰胺（C₂H₄ N₄）为类石墨氮化碳（g-C₃N₄）前驱体,采用液相浸渍-热聚合联合工艺制备出一种可见光响应的g-C₃N₄/伊利石光催化复合材料。利用XRD、FESEM、AFM、UV-Vis、BET及PL对样品的微观结构、界面特性及光学性能进行检测分析,同时考察g-C₃N₄/伊利石光催化复合材料在可见光照射下光催化降解环丙沙星（CIP）的效果。结果表明：相比纯g-C₃N₄,g-C₃N₄/伊利石复合材料在可见光下具有更高的光催化性能,其光催化速率是纯g-C₃N₄的11.26倍;伊利石与g-C₃N₄构成的复合结构能够有效地抑制光生载流子的复合,改善了纯g-C₃N₄材料的吸附性能和光催化活性。     

Deposition of CuWO4 nanoparticles over g-C3N4/Fe3O4 nanocomposite: Novel magnetic photocatalysts with drastically enhanced performance under visible-light

Novel g-C₃N₄/Fe₃O₄/CuWO₄ nanocomposites, as magnetic visible-light-driven photocatalysts, fabricated through a simple refluxing-calcination process. The synthesized photocatalysts were characterized by a series of techniques including XRD, EDX, SEM, TEM, HRTEM, FT-IR, TGA, BET, UV–vis DRS, PL, and VSM. The results showed that heterojunctions are formed between g-C₃N₄, Fe₃O₄, and CuWO₄, which favor suppression of the photogenerated electron/hole pairs from recombination. The resultant g-C₃N₄/Fe₃O₄/CuWO₄ (30%) sample exhibited superior photocatalytic performance. The degradation rate constants on the g-C₃N₄/Fe₃O₄/CuWO₄ (30%) nanocomposite were almost 10.5, 17, 12.5, and 42.5 times higher than those of the pristine g-C₃N₄ for degradations of RhB, MB, MO, and fuchsine, respectively. Moreover, the photocatalyst was magnetically separated and recycled with negligible loss in the activity, which is important for the sustainable photocatalytic processes. Thus, the ternary nanocomposite could have potential applications in different photocatalytic processes.     

可磁分离Fe3O4/g-C3N4复合材料的制备及其性能

为了利用Fe₃O₄的磁响应性及石墨相C₃N₄（g-C₃N₄）优良的光催化活性,首先采用高温热聚合法,以尿素为前驱体制备g-C₃N₄,然后采用水热法合成了可磁分离Fe₃O₄/g-C₃N₄复合材料。利用TEM、XRD、TGA、BET和振动样品磁强计（VSM）等多种测试手段表征分析Fe₃O₄/g-C₃N₄复合材料的形貌、晶型结构、比表面积、成分、饱和磁化强度等。通过模拟太阳光下Fe₃O₄/g-C₃N₄复合材料光催化吸附降解亚甲基蓝（MB）的实验,评价了Fe₃O₄/g-C₃N₄复合材料的吸附性能及光催化性能。结果表明,可磁分离Fe₃O₄/g-C₃N₄复合材料具有较大的比表面积,约为71.89 m²/g;且具有较好的磁性,饱和磁化强度为18.79 emu/g,可实现复合材料的分离回收;光照240 min时,Fe₃O₄/g-C₃N₄复合材料对MB的去除率为56.54%。所制备的Fe₃O₄/g-C₃N₄复合材料具有优良的吸附性能、光催化活性和磁性,并可通过外加磁场进行分离与回收。     

Z-scheme mechanism for methylene blue degradation over Fe2O3/g-C3N4 nanocomposite prepared via one-pot exfoliation and magnetization of g-C3N4

The low surface area, high recombination rate of photogenerated charge carriers, narrow visible range activity, and difficulty in the separation from cleaned solutions limit the wide application of g-C₃N₄ as a photocatalyst. Herein, we have succeeded in developing a one-pot strategy to overcome the above-mentioned difficulties of g-C₃N₄. The broadening of the visible-light response range and inducing magnetic nature to g-C₃N₄ was succeeded by preparing a nanocomposite with Fe₂O₃ via a facile solvothermal method. The preparation method additionally imparted layer exfoliation of g-C₃N₄ as evident from the XRD patterns and TEM images. The strong interaction between the components is revealed from the XPS analysis. The broadened visible-light absorbance of Fe₂O₃/g-C₃N₄ with a Z-scheme photocatalytic degradation mechanism is well evident from the UV‒Vis DRS analysis and PL measurement of the composite with terephthalic acid. The active species of photocatalysis were further investigated using scavenging studies in methylene blue degradation that revealed hydroxyl radicals and holes as the major contributors to the activity of Fe₂O₃/g-C₃N₄.     

Nanoscale ZnS/TiO2 composites: Preparation, characterization, and visible-light photocatalytic activity

Photoactive ZnS/TiO₂ nanocomposites were prepared via microemulsion-mediated solvothermal method. The structure, composition, physicochemical property, and morphology of the composites were characterized by powder X-ray diffraction (XRD), Raman scattering studies, UV diffuse reflectance spectroscopy (UV/DRS), photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM). It showed that the composites were cube-shaped with particle sizes of 10 to 15 nm, and the phase structure for ZnS and TiO₂ in the composites was cubic and anatase, respectively. The content of the ZnS in the composites was 2.1%, 10.7%, and 19.9%, respectively. Compared with the solitary anatase TiO₂, the ZnS/TiO₂ exhibited enhanced visible-light photocatalytic activity for the aqueous parathion-methyl degradation. Factors including the interactions between the phases of ZnS and TiO₂, strong adsorption of the substrate at the surface of the ZnS/TiO₂ nanocomposites, and preassociation of the substrate and composites are responsible for this enhancement photocatalytic activity.     

g-C3N4量子点-TiO2/导电凹凸棒石复合材料的制备及其光催化性能

通过水热法在导电凹凸棒石(C-ATP)表面原位生长TiO₂纳米棒制得毛虫状结构的TiO₂/C-ATP复合材料,然后以TiO₂/C-ATP为载体,在TiO₂纳米棒表面进一步复合g-C₃N₄量子点(CNQD)成功制备了多级结构的CNQD-TiO₂/C-ATP异质结光催化材料。利用XRD、FTIR、SEM/TEM、紫外-可见吸收光谱(UV-Vis-DRS)、荧光发射光谱(PL)、BET比表面积分析仪和光电化学等技术对样品进行表征。在可见光照射下,考察了样品对盐酸四环素(TC)的光催化降解能力。结果表明:与TiO₂/C-ATP和CNQD相比,CNQD-TiO₂/C-ATP大幅提高了可见光响应、吸收能力和光生电子-空穴对的分离效率。当光照时间为120 min时,CNQD-TiO₂/C-ATP对TC去除率可达88%。      

碳氯共掺杂介孔g-C_(3)N_(4)的气泡模板法制备及光催化性能EI北大核心CSCD

以三聚氰胺、葡萄糖和氯化铵为原料制备一种具有高比表面积的碳氯共掺杂介孔g-C_(3)N_(4)(C-Cl-CN)光催化剂,并考察其光催化降解罗丹明B(RhB)的性能。采用XRD,XPS,SEM,UV-Vis DRS和PL测试手段表征和分析催化剂的晶型结构、化学组成及微观形貌。结果表明:C-Cl-CN具有最高的比表面积(108.7 m 2/g),降解RhB的速率常数达到0.02290 min^(-1),是纯g-C_(3)N_(4)的9.4倍,且具有良好的催化稳定性。葡萄糖和氯化铵在聚合过程中起到双气泡模板和元素掺杂剂的作用,一方面提升催化剂的比表面积,另一方面减小能带间隙,增强催化剂的光吸收性能。     

Growth and characterization of Fe3O4 films

Iron oxide films were grown on sapphire substrates by pulsed laser deposition at substrate temperatures between 100 and 700 °C. X-ray diffraction, Raman spectroscopy, and vibrational sample magnetometer analysis revealed that structural and magnetic properties of the iron oxide films strongly depend on the substrate temperature during growth. Single phase Fe₃O₄ film was successfully grown on sapphire substrate at a substrate temperature of 500 °C. The saturation magnetic moment of the single phase Fe₃O₄ film is 499 emu/cm³, which is in good agreement with the value reported for bulk magnetite, suggesting the Fe₃O₄ film is of high crystal quality without antiphase boundaries.     

Co3O4负载rGO/g-C3N4臭氧光催化降解2,4-二氯苯氧乙酸活性研究

通过简单的水热法制备了Co₃O₄/rGO/g-C₃N₄催化剂,并在可见光照射下用于光催化臭氧氧化降解2,4-二氯苯氧乙酸(2,4-D)。利用XRD, SEM, TEM, XPS, UV-vis DRS, FT-IR和瞬态光电流对样品进行测试表征。研究表明,Co₃O₄, rGO和g-C₃N₄形成异质结后光生电子-空穴(e^--h⁺)对的分离效率,e^-的迁移能力以及光催化臭氧氧化活性都明显提升。此外,0.5Co₃O₄/0.25rGO/GCN对2,4-D具有100%的去除率,并具有最高反应速率(k=0.070 9 min^-1)。经过计算得出光催化臭氧氧化2,4-D的协同因子为3.91,表明光催化和臭氧氧化间具有较好的协同效应。活性组分的捕获实验结果表明h⁺和·OH是光催...     

g-C3N4/POPs异质结制备及其可见光催化性能

光催化技术是一种极具应用前景的环境修复技术，开发高效、稳定、具有可见光响应的光催化剂是其研究的重点之一。本文采用常压溶剂热法，以1, 3, 5-三(4-氨基苯基)苯(TAPB)和2, 5-二甲氧基苯-1, 4二甲醛(DMTP)为单体合成的共轭多孔有机聚合物TAPB-DMTP POP为基底，原位负载不同比例的g-C₃N₄，制备g-C₃N₄/POPs复合光催化剂。通过XRD、FTIR、BET、TGA、UV-Vis DRS、电流-时间(i-t)和EIS等测试方法表征了g-C₃N₄/POPs的化学结构与光学特性。在可见光条件下，选择Cr(Ⅵ)为模型污染物探究了不同gC₃N₄负载量的g-C₃N₄/POPs光催化还原效率，并对pH值、催化剂用量和底物浓度等影响因素进一步探究。结果表明：在pH=2条件下，g-C₃N₄/POP-2表现出了最佳...     

WO3/g-C3N4复合光催化剂制备及其可见光催化性能

将自制层状石墨相氮化碳(g-C₃N₄)和WO₃纳米片均匀混合,经煅烧制备WO₃/g-C₃N₄复合半导体。利用XRD、SEM、TEM、UV-Vis DRS和PL对其进行表征。结果表明,g-C₃N₄呈现类石墨烯状片层结构,WO₃为纳米片状结构,且分散在g-C₃N₄表面;与WO₃复合后,UV-Vis吸收边发生了红移,拓宽了g-C₃N₄对可见光的响应。以罗丹明B(RhB)为模拟污染物,考察WO₃/g-C₃N₄的光催化降解性能。WO₃/g-C₃N₄质量比为1∶5时,表现出最佳的光催化活性,可见光照60 min后,RhB降解率可达到94.9%。光催化剂具有良好的稳定性,重复使用6次后,RhB的降解率依然达到88.9%。光催化机制研究表明,超氧自由基(·O₂?)是光催化降解RhB的主要活性物种。      

Facile synthesis and superior photocatalytic and electrocatalytic performances of porous B-doped g-C3N4 nanosheets

As a low-cost visible-light-driven metal-free catalyst, graphitic carbon nitride (g-C₃N₄) has attracted increasing attention due to its wide applications for solar energy conversion, environmental purification, and organic photosynthesis. In particular, the catalytic performance of g-C₃N₄ can be easily modulated by modifying morphology, doping, and copolymerization. Simultaneous optimization, however, has little been achieved. Herein, a facile one-pot strategy is developed to synthesize porous B-doped g-C₃N₄ nanosheets by using H₃BO₃ and urea as the precursor during thermal polymerization. The resultant B-doped g-C₃N₄ nanosheets retain the original framework of bulk g-C₃N₄, while induce prominently enhanced visible light harvesting and narrowing band gap by 0.32 eV compared to pure g-C₃N₄. Moreover, the adsorption capacity and photodegradation kinetics of methylene blue (MB) under visible light irradiation over B-doped g-C₃N₄ nanosheets can be improved by 20.5 and 17 times, respectively. The synthesized porous B-doped g-C₃N₄ nanosheets also exhibit higher activities than pure g-C₃N₄ as bifunctional electrocatalyst for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The enhanced catalyst performance of porous B-doped g-C₃N₄ nanosheets stems from the strong synergistic effect originating from the larger exposed active sites generated by the exfoliation of g-C₃N₄ into nanosheets and the porous structure, as well as the better conductivity owing to B-doping. This work provides a simple, effective, and robust method for the synthesis of g-C₃N₄-based nanomaterial with superior properties to meet the needs of various applications.     

High efficiency visible-light-driven Fe2O3-xSx/S-doped g-C3N4 heterojunction photocatalysts: Direct Z-scheme mechanism

Several nanoporous Fe_2 O_3-xSx/S-doped g-C_3 N_4(CNS) Z-scheme hybrid heterojuctions have been successfully synthesized by one-pot in situ growth of the Fe_2O_3-xSx particles on the surface of CNS. The characterization results show that S-doping in the g-C3 N4 backbone can greatly enhance the charge mobility and visible light harvesting capability. In addition, porous morphology of hybrid composite provides available open pores for guest molecules and also improves light absorbing property due to existence of multiple scattering effects. More importantly, the Fe_2 O_3-xSx nanoparticles formed intimate heterojunction with CNS and developed the efficient charge transfer by extending interfacial interactions occurred at the interfaces of both components. It has been found that the Fe_2 O_3-xSx/CNS composites have an enhanced photocatalytic activity under visible light irradiation compared with isolated Fe_2 O_3 and CNS components toward the photocatalytic degradation of methylene blue(MB). The optimal loaded Fe_2 O_3-xSx value obtained is equal to 6.6 wt% that provided 82% MB photodegradation after 150 min with a reaction rate constant of 0.0092 min~(-1) which was faster than those of the pure Fe_2 O_3(0.0016 min~(-1))and CNS(0.0044 min~(-1)) under the optimized operating variables acquired by the response surface methodology. The specific surface area and the pore volume of Fe_2 O_3(6.6)/CNS hybrid are 33.5 m~2/g and0.195 cm~3/g, which are nearly 3.8 and 7.5 times greater compared with those of the CNS, respectively. The TEM image of Fe_2 O_3(6.6)/CNS nanocomposite exhibits a nanoporous morphology with abundant uniform pore sizes of around 25 nm. Using the Mott-Schottky plot, the conduction and valence bands of the CNS are measured(at pH = 7) equal to-1.07 and 1.48 V versus normal hydrogen electrode(NHE), respectively.Trapping tests prove that ·OH-and ·O_2-radicals are major active species in the photocatalytic reaction.It has been established that formation of the Z-scheme Fe_2 O_3(6.6)/CNS heterojunction between CNS and Fe_2 O_3 directly produces ·OH as well as ·O_2-radicals which is consistent with the results obtained from trapping experiments.     

Synthesis and characterization of C3N4 nanowires and pseudocubic C3N4 polycrystalline nanoparticles

C₃N₄ nanowires and pseudocubic C₃N₄ polycrystalline nanoparticles have been synthesized by the reaction between C₃N₃Cl₃ and NaN₃ with Zn powder as catalyst. The process was carried out using a constant-pressure benzene thermal method at 40 MPa and 220 °C. The prepared nanowires have a diameter range of 3-6 nm and length range of 100-200 nm, while the diameters of the nanoparticles range from 10 nm to 40 nm. The as-prepared samples were characterized by X-ray powder diffraction (XRD), Fourier transform spectroscopy (FTIR), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS).     

Fabrication and characterization of uniform Fe3O4 octahedral micro-crystals

Uniform Fe₃O₄ octahedral microcrystals with perfect appearance have been successfully synthesized by a Triton X100-assisted polyol process. During the polyols process for the preparation of Fe₃O₄ octahedra, the introduction of Triton X100 decreases significantly the needed concentration of NaOH. The results show that Fe₃O₄ octahedra are composed of eight triangular sheets, which are equilateral triangles. The edge size of Fe₃O₄ octahedron is about 4 μm. The magnetic properties of Fe₃O₄ octahedral particles were evaluated on a SQUID magnetometer at room temperature. The value of saturation magnetization for Fe₃O₄ octahedra is 90 emu/g, which is close to the value of bulk magnetite. The remnant magnetization and coercive force of Fe₃O₄ octahedra are considerably low, which are rare for the Fe₃O₄ particles with the size scale of micrometers. The Fe₃O₄ octahedral microcrystals show high saturation magnetizations and very low coercivities.     

WS2/g-C3N4异质结光催化分解水制氢性能及机制

通过溶剂蒸发和二次高温煅烧石墨相碳化氮(g-C₃N₄)纳米片和WS₂纳米片混合物构建WS₂/g-C₃N₄异质结,该异质结保留g-C₃N₄和WS₂主体结构的同时,在界面处形成化学键,确保该异质结的化学稳定性和热稳定性。光催化分解水制氢实验表明,WS₂纳米片含量为3wt%时光催化制氢速率高达68.62 μmol/h,分别是g-C₃N₄纳米片和WS₂纳米片的2.53倍和15.29倍,表明异质结的构建可大幅提升g-C₃N₄的光催化性能,循环实验表明该异质结在5次循环实验后光催化性能没有明显下降,表明该异质结的稳定性较好。光电性能测试表明异质结的构建不仅提高激发电子的转移效率,同时抑制激发电子空穴的复合率,大幅提升激发电子的利用效率,致使光催化分解水制氢速率较g-C₃N₄纳米片和WS₂纳米片大幅提升。      

Controllable synthesis and magnetic properties of Fe3O4 and Fe3O4@SiO2 microspheres

We present a systematic study on the preparation, microstructure, and magnetic properties of Fe₃O₄ microspheres and Fe₃O₄@SiO₂ microspheres. Results showed that Fe₃O₄ microspheres’ diameter can be tuned by Fe³⁺ concentration, whereas their average grain size can be tuned by polyethylene glycol (PEG) 2000 dosage or PEG molecular weight. The magnetic saturation value of Fe₃O₄ microspheres was observed to be dependent on their average grain size, but not the sphere diameter. Fe₃O₄@SiO₂ microspheres with different magnetic saturation values were achieved by adjusting shell thickness. Furthermore, the synthesized Fe₃O₄ and Fe₃O₄@SiO₂ microspheres with high and controllable magnetic saturation value endow them with great application potentials.     

纳米Fe3O4/聚苯胺复合粒子的制备及其磁性能研究

用水解沉淀法制备纳米Fe3O4,然后在其溶液中原位合成聚苯胺,得到纳米Fe3O4/聚苯胺复合粒子.通过XRD、TEM、JDM等测试对纳米复合粒子的形态、结构及磁性能进行了研究.实验制备的纳米Fe3O4粒子粒径为30nm左右,在其表面沉积聚苯胺后,复合粒子的粒径达到了50nm左右.与纳米Fe3O4粒子相比,纳米Fe3O4/聚苯胺复合粒子的XRD峰形变得更为明锐.纳米复合粒子的磁性能表现出软磁性,与纳米Fe3O4粒子相比,矫顽力减小为0,这可以大大减小材料的磁滞损耗和退磁难度,性能得到改善.     

g-C3N4/Bi12O17Cl2复合物的制备及其光催化性能

以硝酸铋、氯化钠和氢氧化钠为原料用液相沉淀法制备g-C₃N₄/Bi₁₂O₁₇Cl₂复合光催化剂,并用X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、扫描电子显微镜(SEM)、紫外-可见漫反射光谱(UV-Vis DRS)等手段表征其组成、微观形貌和性能,以罗丹明B为模拟污染物研究了在可见光照射下g-C₃N₄对g-C₃N₄/Bi₁₂O₁₇Cl₂复合光催化剂活性的影响及其光催化机理。结果表明,2% (质量分数) g-C₃N₄/Bi₁₂O₁₇Cl₂复合光催化剂的光催化性能最好,见光90 min后对罗丹明B的降解率达到98%。