Synthesis and study of Bi2Ti2O7/TiO2 composites as efficient visible-light-active photocatalysts in the reduction of aqueous Cr(VI)

In this work, Bi_2Ti_2O_7/TiO_2 composites were synthesized and studied as potential visible-light-activated photocatalysts in the reduction of aqueous Cr(VI). Bi_2Ti_2O_7/TiO_2 composites with tunable compositions were synthesized via a solvothermal-calcination two-step method, simply by changing the molar ratios of Bi(NO_3)_3·5H_2O to tetrabutyl titanate in the reactants. The compositions, structures and optical properties of the as-synthesized Bi_2Ti_2O_7/TiO_2 composites were characterized by X-ray diffraction, field emission scanning electron microscopy and UV–vis diffuse reflectance spectra. The photocatalytic activity of the as-synthesized Bi_2Ti_2O_7/TiO_2 composites was tested in the reduction of aqueous Cr(VI)under visible-light(λ420 nm) irradiation, and compared with that of TiO_2 nanoparticles. It was observed that the as-synthesized Bi_2Ti_2O_7/TiO_2 composites exhibited much higher photocatalytic activity than TiO_2 nanoparticles, and the most efficient composite(300 mg) can achieve the complete reduction of Cr(VI) in 300 mL of 50 mg/L K_2Cr_2O_7 aqueous solution under visible-light(λ420 nm)irradiation in 90 min.     

富含光诱导氧空位Bi12O17Br2的制备及其高效光催化固氮性能

采用一步水热法制备了Bi₁₂O₁₇Br₂光催化剂,其平均微片尺寸为1.2μm,比表面积约为29 m²·g^-1。Bi₁₂O₁₇Br₂的禁带宽度为2.42 eV,能够响应可见光。值得注意的是,在光照条件下Bi₁₂O₁₇Br₂表面能够产生氧空位;光诱导氧空位不仅能促进氮气在催化剂表面的吸附,而且对吸附的氮气分子的活化起到至关重要的作用。实验结果表明在可见光照射下,Bi₁₂O₁₇Br₂光催化剂上的氨生成速率为337.6μmol·g^-1·h^-1。在可见光的驱动下,Bi₁₂O₁₇Br₂光催化剂能够实现氮气与水反应生成氨的过程。     

Characterizations and photocatalytic activity of nanocrystalline La1.5Ln0.5Ti2O7 (Ln = Pr, Gd, Er) solid solutions prepared via a polymeric complex method

Nanocrystalline La_1.5Ln_0.5Ti₂O₇ (Ln = Pr, Gd, Er) solid solutions were prepared by a polymeric complex method. The samples were characterized by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS), energy dispersive X-ray spectrum (EDS), thermogravimetric analyses (TGA) and differential thermal analyses (DTA). The photocatalytic activity of La_1.5Ln_0.5Ti₂O₇ (Ln = Pr, Gd, Er) was evaluated by the photocatalytic degradation of methyl orange (MO). La_1.5Gd_0.5Ti₂O₇ showed the best photocatalytic activity and it was supposed that the half-filled electronic configuration of Gd³⁺ can promote charge transfer and enhance the photocatalytic activity. The difference in the photocatalytic activity observed for La_1.5Ln_0.5Ti₂O₇ (Ln = La, Pr, Gd, Er) can be related to the different Ln 4f shell.     

超临界水热极速合成异质结构H4SiW12O40/Bi2WO6光催化剂及其脱氮性能

采用超临界水热合成方式极速合成一种H_4SiW_(12)O_(40)/Bi_2WO_6光催化剂,通过X射线衍射(XRD)、场发射扫描电子显微镜(SEM)、透射电子显微镜(TEM)、比表面积及孔隙度(BET)测定对所合成催化剂的结构和性质进行了考察,并以吡啶含量为15 mg/g的模拟油对光催化剂的脱氮效果进行评价。结果表明,该光催化剂为二维纳米片自组装成的三维球状结构,其中,H_4SiW_(12)O_(40)与Bi_2WO_6不是简单的固载关系而是在超临界水热条件下生成一种新的晶相,正是由于这种晶相的存在,使得H_4SiW_(12)O_(40)牢固固载在Bi_2WO_6光催化剂本体上的同时,对光生载流子进行了有效疏导,提升了H_4SiW_(12)O_(40)/Bi_2WO_6光催化剂的使用寿命和光催化活性。本研究针对光催化剂制备周期与晶形发育的矛盾,将超临界水热技术与光催化剂模板导向合成技术有机结合,在获得良好晶形异质结构H_4SiW_(12)O_(40)/Bi_2WO_6光催化剂的同时明显缩短了光催化剂的制备周期,从而降低了催化剂的制备成本,攻克了光催化剂工业化应用的主要矛盾,所制备的H_4SiW_(12)O_(40)/Bi_2WO_6光催化剂轻质油脱氮效率达97%以上。     

Lotus-stalk Bi4Ge3O12 as binder-free anode for lithium and sodium ion batteries

The synthesized lotus-stalk Bi₄Ge₃O₁₂ utilized as binder-free anode for LIBs demonstrates excellent cycling performance. The synthesized lotus-stalk Bi₄Ge₃O₁₂ is composed of nanosheets, which is contribute to outstanding lithium storage performance.     

TiO2/Bi2O3纳米复合体的制备及可见光催化产氢性能

首先采用相分离的水解-溶剂热法制备了Bi₂O₃纳米粒子,然后利用简单的湿化学法在Bi₂O₃表面负载不同比例的TiO₂纳米颗粒,进而得到TiO₂/Bi₂O₃纳米复合体。通过气氛调控的表面光电压谱(SPS)等测试表明,表面负载适量的TiO₂后能够提高Bi₂O₃光生电荷分离。可见光催化产氢和降解污染物测试结果进一步证明,表面负载适量的TiO₂后可显著提高其可见光催化活性,其中Ti/Bi摩尔比为7%时具有最高的光催化活性。这主要归因于TiO₂具有较为合适的导带能级位置,可以接收Bi₂O₃在可见光激发下所产生的高能级电子,从而抑制光生电子-空穴对复合,并且维持了高能级电子较高的还原能力。     

Bi_2MoO_6/BiVO_4异质结的水热合成和可见光催化活性(英文)

采用一步水热法制备Bi2MoO6/BiVO4复合光催化剂.利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、高分辨透射电子显微镜(HRTEM)等手段对其晶体结构和微观结构进行了表征.结果表明,Bi2MoO6纳米粒子沉积在BiVO4纳米片表面从而形成异质结结构.紫外-可见漫反射光谱(UV-Vis DRS)表明所制备的Bi2MoO6/BiVO4异质结较纯相Bi2MoO6和BiVO4对可见光吸收更强.由于形成异质结结构及其光吸收性能使Bi2MoO6/BiVO4光催化活性有较大提高.可见光下(λ420 nm)光催化降解罗丹明B(RhB)实验结果表明,Bi2MoO6/BiVO4光催化活性较纯相Bi2MoO6和BiVO4高.Bi2MoO6/BiVO4样品光催化性能提高的原因是Bi2MoO6和BiVO4形成异质结,从而有效抑制光生电子-空穴对的复合,增大了可见光吸收范围及比表面积.     

Synthesis of titania and titanate nanomaterials and their application in environmental analytical chemistry

TiO₂ nanoparticles and H₂Ti₂O₅·H₂O, Na₂Ti₂O₄(OH)₂ nanotubes were synthesized by solvothermal method and their applications in the degradation of active Brilliant-blue (KN-R) solution were investigated. The experimental results revealed that the synthesized TiO₂ nanoparticles had a good crystallinity and a narrow size distribution (about 4–5 nm); the obtained H₂Ti₂O₅·H₂O, Na₂Ti₂O₄(OH)₂ were tubelike products with an average diameter of 20–30 and 200–300 nm length. The three catalysts we synthesized had some hydroxyl groups and the maximum absorption boundaries of the samples were all red-shifted, which indicated the samples had a promising prospect in photocatalysis.

The results of the photocatalytic experiments indicated that the photocatalytic activity of the samples was: TiO₂ > H₂Ti₂O₅·H₂O > Na₂Ti₂O₄(OH)₂, which was in good accordance with the fact of FTIR and UV–vis absorption spectra. The formation mechanism of these nanostructures was also discussed.     

Photocatalytic degradation of amoxicillin by carbon quantum dots modified K2Ti6O13 nanotubes: Effect of light wavelength

Novel carbon quantum dots modified potassium titanate nanotubes (CQDs/K₂Ti₆O₁₃) composite was synthesized and exhibited high photocatalytic activity for degradation of amoxicillin under UV and visible lights with nine wavelengths. Better amoxicillin removal was achieved at lower wavelength irradiation due to its higher photo energy.     

Soft chemistry synthesis of the perovskite CaCu3Ti4O12

The perovskite CaCu₃Ti₄O₁₂ (CCT) has been obtained after calcination of oxalate precursors at 900–1000 °C in air. Those precursors are prepared using a soft chemistry method, the coprecipitation. The oxalate powders consist of disk-like particles of 2–3 μm diameter and 300–400 nm thickness. By varying the ratio of the initial amounts of metal chlorides, additional phases (CaTiO₃, TiO₂ and CuO) could be obtained besides CCT. The corresponding multiphased ceramics present improved dielectric properties.     

高催化活性2D/2D Ti3C2/Bi4O5Br2纳米片异质结的构建及其可见光催化去除NO

This study concentrated on the production of a two-dimensional and two-dimensional (2D/2D) Ti₃C₂/Bi₄O₅Br₂ heterojunction with a large interface that applied as one of the novel visible-light-induced photocatalyst via the hydrothermal method. The obtained photocatalysts enhanced the photocatalytic efficiency of the NO removal. The crystal structure and chemical state of the composites were characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that Ti₃C₂, Bi₄O₅Br₂, and Ti₃C₂/Bi₄O₅Br₂ were successfully synthesized. The experimental results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the prepared samples had a 2D/2D nanosheet structure and large contact area. This structure facilitated the transfer of electrons and holes. The solar light absorptions of the samples were evaluated using the UV-Vis diffuse reflectance spectra (UV-Vis DRS). It was found that the absorption band of Ti₃C₂/Bi₄O₅Br₂ was wider than that of Bi₄O₅Br₂. This represents the electrons in the Ti₃C₂/Bi₄O₅Br₂ nanosheet composites were more likely to be excited. The photocatalytic experiments showed that the 2D/2D Ti₃C₂/Bi₄O₅Br₂ composite with high photocatalytic activity and stability. The photocatalytic efficiency of pure Bi₄O₅Br₂ for the NO removal was 30.5%, while for the 15%Ti₃C₂/Bi₄O₅Br₂ it was 57.6%. Moreover, the catalytic reaction happened in a short period. The concentration of NO decreased exponentially in the first 5 min, which approximately reached the final value. Furthermore, the stability of 15%Ti₃C₂/Bi₄O₅Br₂ was favorable: the catalytic rate was approximately 50.0% after five cycles of cyclic catalysis. Finally, the scavenger experiments, electron spin resonance spectroscopy (ESR), transient photocurrent response, and surface photovoltage spectrum (SPS) were applied to analyze the photocatalytic mechanism of the composite. The results indicated that the 2D/2D heterojunction Ti₃C₂/Bi₄O₅Br₂ improved the separation rate of the electrons and holes, thus enhancing the photocatalytic efficiency. In the photocatalytic reactions, the photogenerated electrons (e⁻) and superoxide radical (·O₂⁻) were critical active groups that had a significant role in the oxidative removal of NO. The in situ Fourier-transform infrared spectroscopy (in situ FTIR) showed that the photo-oxidation products were mainly NO₂⁻ and NO₃⁻. Based on the above experimental results, a possible photocatalytic mechanism was proposed. The electrons in Bi₄O₅Br₂ were excited by visible light. They jumped from the valence band (VB) of Bi₄O₅Br₂ to the conduction band (CB). Then, the photoelectrons transferred from the CB of Bi₄O₅Br₂ to the Ti₃C₂ surface, which significantly promoted the separation of the electron-hole pairs. Therefore, the photocatalytic efficiency of Ti₃C₂/Bi₄O₅Br₂ on NO was significantly improved. This study provided an effective method for preparing 2D/2D Ti₃C₂/Bi₄O₅Br₂ nanocomposites for the photocatalytic degradation of environmental pollutants, which has great potential in solving energy stress and environmental pollution.     

多酸掺杂Bi2O3-x/Bi光催化剂用于高效可见光催化降解四溴双酚A和NO去除

四溴双酚A(TBBPA)是一种重要的塑料添加剂和阻燃剂,广泛用于树脂、塑料、胶黏剂以及涂料中.它不仅是持久性的机污染物,还是一种内分泌干扰物,具有免疫毒性、神经毒性和细胞毒性.NOx,特别是NO,是主要的大气污染物之一,是形成PM2.5的重要前体,也容易引起酸雨,引发光化学烟雾、臭氧损耗、温室效应等,严重危害生态环境和...     

钨酸铋量子点和纳米片修饰石墨相氮化碳复合催化剂的制备及其可见光催化活性增强

利用超声-水热法、使用油酸钠辅助合成钨酸铋(Bi₂WO₆)量子点/纳米片修饰的石墨相氮化碳(g-C₃N₄)(Bi₂WO₆/g-C₃N₄)复合光催化剂。 通过X射线粉末衍射(XRD)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、紫外可见漫反射光谱(UV-Vis DRS)、N₂吸附-脱附等技术手段获得Bi₂WO₆/g-C₃N₄催化剂的组成、结构和光吸收性能,分析合成机理。 以罗丹明B(RhB)水溶液为模拟污染物,考察Bi₂WO₆/g-C₃N₄复合催化剂的可见光催化活性。 结果表明:g-C₃N₄和Bi₂WO₆的质量比为3:7的Bi₂WO₆/g-C₃N₄-30具有最有效的异质界面,电化学阻抗和光电流测试结果显示该催化剂的光生载流子传输速率快、复合率低,可见光照射120 min对RhB的降解率达到95.8%;通过活性物质捕捉实验获知光生空穴是光催化反应中的主要活性物质,分析异质界面对光催化活性的影响,进而提出光催化反应机理。     

表面活性剂修饰碳酸氧铋的制备及光催化性能

采用水热法,以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、非离子型表面活性剂聚乙二醇8000(PEG8000)、阴离子表面活性剂十二烷基硫酸钠(SDS)及SDS与CTAB耦合修饰Bi₂O₂CO₃。 系统地研究了表面活性剂种类及用量对Bi₂O₂CO₃晶面、形貌、光吸收特性及光催化降解效率的影响。 以紫外光下降解罗丹明B(RhB),考察样品的光催化性能。 结果表明,当Bi盐投加量为6 mmol(2.9106 g)时,SDS对Bi₂O₂CO₃的修饰对其光催化活性有所抑制;0.6 g CTAB修饰Bi₂O₂CO₃能有效提高其光催化活性;0.3 g SDS与CTAB耦合修饰Bi₂O₂CO₃就能有效提高其光催化活性;0.3 g PEG8000修饰Bi₂O₂CO₃也能使其光催化活性有所提高。     

Hydrothermal syntheses and crystal structures of bimetallic cluster complexes [{Cd(phen)2}2V4O12]·5H2O and [Ni(phen)3]2[V4O12]·17.5H2O

The hydrothermal reactions of vanadium oxide starting materials with divalent transition metal cations in the presence of nitrogen donor chelating ligands yield the bimetallic cluster complexes with the formulae [{Cd(phen₂)₂V₄O₁₂]·5H₂O (1) and [Ni(phen)₃]₂[V₄O₁₂]·17.5H₂O (2). Crystal data: C₄₈H₅₂Cd₂N₈O₂₂V₄ (1), triclinic. a=10.3366(10), b=11.320(3), c=13.268(3) Å, =103.888(17)°, β=92.256(15)°, γ=107.444(14)°, Z=1; C₇₂H₁₃₁N₁₂Ni₂O_29.5V₄ (2), triclinic. a=12.305(3), b=13.172(6), c=15.133(4), =79.05(3)°, β=76.09(2)°, γ=74.66(3)°, Z=1. Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range 1.59° <θ<26.02° and 2.01°<θ<25.01° using the ω-scan technique, respectively. The structure of 1 consists of a [V₄O₁₂]⁴⁻ cluster covalently attached to two {Cd(phen)₂}²⁺ fragments, in which the [V₄O₁₂]⁴⁻ cluster adopts a chair-like configuration. In the structure of 2, the [V₄O₁₂]⁴⁻ cluster is isolated. And the complex formed a layer structure via hydrogen bonds between the [V₄O₁₂]⁴⁻ unit and crystallization water molecules.     

碱性介质中制备纳米四氧化三锰及其超级电容特性

比较了不同碱溶液中纳米Mn₃O₄的制备及其超级电容性能。用X射线粉末衍射仪、扫描电子显微镜和原子力显微镜等技术手段分别测试了晶体结构和表面形貌。用循环伏安、恒流充放电和交流阻抗测试了材料的电化学性能。结果表明,在氢氧化钠、氨水中Mn²⁺沉淀氧化可以直接制备纳米Mn₃O₄;碳酸钠中先生成MnCO₃,加氢氧化钠可转化为纳米Mn₃O₄。NaOH、NH₃和Na₂CO₃ 3种介质中制备的Mn₃O₄晶粒尺寸分别为29.5、20.2和36.3 nm。纳米Mn₃O₄经连续充放电循环后可活化为Birnessite-type MnO₂。氨水中制备的Mn₃O₄活化后比容量最大,达到239 F/g,是一种具有应用前景的超级电容器材料。     

The Influence of Heat Treatment Mode on the Properties of Bi4Ti3O12 Thin Films by Chemical Solution Deposition Technique

Bi₄Ti₃O₁₂ thin films were prepared by chemical solution deposition technique on n-Si(lOO). Bismuth nitrate and titanium butoxide were used as starting materials. In this paper, we used this technique to prepare Bi₄Ti₃O₁₂ thin films heat treated by both rapid annealing for 30 seconds in a rapid annealing heater and annealing in a furnace for 30 minutes, and found that the heat treat mode greatly influences the properties of the films. The crystallization temperature of the film made from rapid annealing is about 500℃, while that of the film prepared by heating in a furnace is about 550℃. X-ray diffraction pattern of the film heat treated by the former has stronger (004), (006), (008), (0010) peaks than that of the film heat treated by the latter, which suggests that the rapid annealing heat treat mode favors preferential c-oriental film. The grain size of the film obtained by rapid annealing is smaller than that of the film prepared by heating in a furnace. When the films were both annealed at 600℃,the coercive field of the film heat treated by the former is 45 kV/cm, while that of the film heat treated by the latter is 87 kV/cm.     

Bi4V2O11/石墨烯异质结光催化剂的制备及其在降解抗体污染物中应用

发展和设计高效、廉价和稳定的光催化剂用于抗生素污染物降解仍然存在巨大的挑战。 本文通过一种便捷的水热方法制备了Bi₄V₂O₁₁/石墨烯复合材料并用于可见光下抗生素污染物光催化降解。 通过自由基追踪实验,确认了光催化降解过程中活性物质为h⁺和·OH基团。 根据实验结果,提出了相应的反应机理。 石墨烯的引入可以有效地促进光生电子-空穴对的分离,从而增强光催化活性。 该复合催化剂展现出良好的活性和稳定性。 该方法以石墨烯为载体制备了光催化降解材料,为高性能光催化剂的制备提供了参考。     

Preparation of Functionalized Fe3O4@SiO2 Magnetic Nanoparticles for Monoclonal Antibody Purification

Magnetic Fe₃O₄@SiO₂ nanoparticles with superparamagnetic properties were prepared via a reverse mi-croemulsion method at room temperature. The as-prepared samples were characterized by transmission electron mi-croscopy(TEM), X-ray diffractometry(XRD), and vibrating sample magnetometry(VSM). The Fe₃O₄@SiO₂ nanoparticles were modified by (3-aminopropyl)triethoxysilane(APTES) and subsequently activated by glutaraldehyde(Glu). Protein A was successfully immobilized covalently onto the Glu activated Fe₃O₄@SiO₂ nanoparticles. The adsorption capacity of the nanoparticles was determined on an ultraviolet spectrophotometer(UV) and approximately up to 203 mg/g of protein A could be uniformly immobilized onto the modified Fe₃O₄@SiO₂ magnetic beads. The core-shell of the Fe₃O₄@SiO₂ magnetic beads decorated with protein A showed a good binding capacity for the chime-ric anti-EGFR monoclonal antibody(anti-EGFR mAb). The purity of the anti-EGFR mAb was analyzed by virtue of HPLC. The protein A immobilized affinity beads provided a purity of about 95.4%.     

微波液相法一步合成H3PW12O40/Bi2WO6光催化剂及其脱氮性能

采用微波液相法一步合成了固载型H₃PW₁₂O₄₀/Bi₂WO₆光催化剂. 通过紫外-可见漫反射光谱(UV-Vis)、 场发射扫描电子显微镜(SEM)、 表面积及孔隙度(BET)测定、 氨气程序升温脱附(NH₃-TPD)、 吡啶吸附红外光谱(Py-FTIR)和X射线衍射(XRD)对所合成催化剂的结构和性质进行了考察, 并以吡啶浓度为15 mg/g的模拟油对光催化剂的脱氮效果进行评价. 结果表明, 与传统浸渍固载法相比, 微波液相一步法不仅能高效合成H₃PW₁₂O₄₀/Bi₂WO₆光催化剂, 且所合成的催化剂能被低能量的光激发. 固载H₃PW₁₂O₄₀不但能提高Bi₂WO₆纳米颗粒的表面酸量, 还能通过改变Bi₂WO₆前驱液的酸强度来调控催化剂形貌. 在H₃PW₁₂O₄₀固载量为15%(质量分数), 微波功率为800 W, 反应时间为90 min条件下得到的H₃PW₁₂O₄₀/Bi₂WO₆的光催化脱氮活性最高, 在催化剂与模拟油质量比为1/300, 500 W氙灯光照60 min的最佳光催化反应条件下, 模拟油脱氮率达到92.63%.