共沉淀法制备Bi12TiO20纳米粉体及其光催化性能研究

以五水硝酸铋（Bi（NO3）3.5H2O）和钛酸四丁酯（C4H9O）4Ti）为反应物,利用共沉淀法制备Bi12TiO20前驱体,通过一定的热处理获得Bi12TiO20纳米粉体。采用XRD和TEM对其结构和形貌进行了表征,以紫外及可见光为光源、甲基橙为目标降解物,评价了Bi12TiO20粉体的光催化性能。结果表明：在热处理温度为550℃时合成的Bi12TiO20粉体,紫外-可见漫反射光谱测试显示吸收带发生了红移,当光照时间为4h时,其在紫外光和可见光下对甲基橙的降解率分别为93%和54%。     

Mo掺杂TiO2的制备及其光催化性能

以钛酸四丁酯为原料,采用溶胶-凝胶法制备了纯TiO_2与Mo掺杂TiO_2纳米粒子,并利用XRD、UV-VIS、XPS等测试手段对制备的TiO_2纳米粒子进行表征;以亚甲基蓝为光催化反应模型,考察了煅烧温度、钼掺杂量等对TiO_2晶格畸变,晶粒大小,晶型,光学性能及光催化活性的影响.结果表明:大部分Mo~(6+)取代晶格中Ti~(4+)的位置,引起晶格畸变,抑制晶粒长大与TiO_2由锐钛矿相向金红石相转变;样品经450 ℃煅烧, 随Mo掺杂量增加,激发波长红移增加,当煅烧温度升至600 ℃,1.8%Mo-TiO_2样品中锐钛矿相含量增加,致光激发波长蓝移;适量的Mo掺杂有利于提高TiO_2光催化效果,Mo掺杂物质的量分数为1.8%, 经600 ℃煅烧后样品的光催化性能最佳.     

溶胶-凝胶法制备B掺杂TiO2纳米粉体及其光催化性能研究

本研究采用溶胶-凝胶法制备了B掺杂TiO2纳米粉体.采用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-Vis)等测试手段对其进行了表征,以亚甲基蓝为模拟污染物,评价了不同热处理条件下的粉体在可见光下的光催化活性.结果表明:B掺杂对TiO2表面形貌没有明显影响,但抑制了TiO2晶粒的长大和TiO2由锐钛矿型向金红石型的转变;部分B以B2O3的形式存在,部分B掺入到TiO2晶格间隙形成B-O-Ti键;B掺杂未改变TiO2的吸收边带,且使得TiO2对可见光的吸收有所减弱;B掺杂能有效促进TiO2表面活性基团Ti-OH的生成,该基团能够有效捕获空穴,从而提高光催化活性;B掺杂TiO2粉体在650℃煅烧的催化活性最高,对亚甲基蓝的2h降解率比未掺杂TiO2提高16.51％.     

铁掺杂氧化锌纳米晶的制备及光催化性能研究

通过水热法制备了铁掺杂氧化锌纳米晶,采用红外、X射线衍射（XRD）、可见光谱对其进行了表征,并以铁掺杂纳米氧化锌对亚甲基蓝进行催化降解实验来检验其催化降解性能,结果表明当Fe^＋／ZnO纳米晶浓度为1．0mol／L、亚甲基蓝质量浓度为5mg／L、太阳光照射3h时,甲基橙降解效果最好,降解率达90％以上。     

铁掺杂介孔二氧化钛的制备及其光催化性能

采用溶胶-凝胶法,以价廉的硫酸钛和硝酸铁为原料制备了不同含量的掺铁介孔二氧化钛。采用 X 射线衍射、扫描电子显微镜、热重-差示扫描量热分析、N2吸附-脱附、X 射线光电子能谱、紫外-可见漫反射对样品进行表征。以亚甲基蓝（MB）为目标降解物,对催化剂的光催化性能进行了研究。结果表明：铁以 Fe3＋、Fe2＋取代 Ti4＋进入 TiO2的晶格。适量掺铁使 TiO2的吸收带边发生红移,有利于提高样品光催化性能和保持良好的重复套用活性。最佳掺铁量（摩尔比）为 n（Fe）/n（Ti） = 2%,对应样品颗粒大小为 0.1～0.2 μm,比表面积为 117.6 m2/g,孔容积为 0.434 cm3/g,平均孔径为13 nm。重复套用 4 次后,240 min 内对 MB 的总脱色率仍然达 89.0%,降解率达 70.7%.     

Bi，Co离子掺杂改性TiO2光催化剂的研究

采用溶胶凝胶法,通过Bi,Co离子掺杂改性TiO2光催化剂,改善了TiO2的光催化性能,并采用改性的催化剂对偶氮染料甲基橙进行降解实验,验证了改性的效果以及影响因素。     

La掺杂纳米TiO2的制备及其节能灯光催化性能研究

采用溶胶-凝胶法制备了La掺杂的纳米TiO2光催化剂并对其进行了XRD物相分析。以节能灯为光源,考察了催化剂组成、催化剂加入量、反应温度等对其光催化降解亚甲基蓝性能的影响。结果表明:La的掺杂能明显提高纳米TiO2在节能灯照射下的光催化活性。其中,La0.5/TiO2的催化效果最佳,当反应温度40℃,催化剂加入量0.625g/L,反应液pH值5.33时,4h的降解率可达97.71%。XRD分析结果显示,La的掺杂抑制了锐钛矿向金红石晶型的转变,细化了晶粒。     

生物质模板法制备Bi掺杂ZnO及其太阳光催化性能

采用生物质模板法,以脱脂棉为模板、Zn(OAC)_2·2H_2O为锌源、Bi(NO_3)_3·5H_2O为铋源、乙醇-水为溶剂,在不同的浸泡时间、焙烧温度、焙烧时间和掺杂摩尔分数下通过浸渍-热转化制备了一系列Bi_2O_3/ZnO催化剂。使用扫描电子显微镜、热重分析、X-射线衍射等技术表征了产物形貌和结构。以亚甲基蓝作为模板反应,太阳光为光源,考察了Bi_2O_3/ZnO系列材料的光催化活性。结果表明,在浸泡2 h、焙烧温度为600℃、焙烧时间为2 h的条件下制得的Bi掺杂量为Zn摩尔分数1.0%的Bi_2O_3/ZnO催化剂,在太阳光照射390 min时对亚甲基蓝的降解效果最佳,降解率高达95.21%。与纯ZnO相比,降解率提高了16.77%。Bi_2O_3/ZnO具有良好的稳定性和可循环使用性,在光降解偶氮染料方面具有潜在的应用价值。     

N、Bi共掺杂的TiO_2可见光光催化剂的制备及其光催化性能

采用溶胶-凝胶法制备系列BixTi1-xO_2光催化剂以及N和Bi共掺杂Ti O_2光催化剂,采用XRD、UV-Vis、N2-物理吸附和TEM等对催化剂进行微观结构表征,以普通节能灯为光源,考察催化剂光催化氧化室内甲醛的性能。结果表明,在Bi掺杂的Ti O_2光催化剂体系中,Bi0.15Ti0.85O_2光催化剂催化降解甲醛效果最佳,400℃焙烧2.5 h,节能灯光照48 h,可将(1.05±0.05)mg·m-3甲醛降解至0.08 mg·m-3,甲醛转化率92.8%,达到室内空气质量标准。当N与Bi共掺杂时,节能灯光照24 h,Bi0.15Ti0.85O_2-N(0.2)光催化剂表现出最佳的光催化氧化降解甲醛性能,即可将甲醛由(1.05±0.05)mg·m-3降解至0.082 mg·m-3,甲醛转化率达92.0%,较Bi0.15Ti0.85O_2催化剂光催化效率提高50%。     

Sintering Mechanism and Microwave Dielectric Properties of Bi12TiO20 Ceramics

A homogeneous Bi₁₂TiO₂₀ phase was developed in a specimen that was calcined at 700°C without the formation of a secondary phase. A small amount of the Bi₁₂TiO₂₀ phase melted during sintering and assisted the densification of the specimen. The Bi₂O₃ and Bi₈TiO₁₄ secondary phases were found in all specimens. All the specimens that were sintered at temperatures ≥775°C exhibited high relative densities above 98% of the theoretical density. The Q × f value of the Bi₁₂TiO₂₀ ceramics was influenced by the grain size. The Bi₁₂TiO₂₀ ceramics sintered at 800°C for 5 h showed promising microwave dielectric properties of ε_r = 41, Q × f = 10 400 GHz, and τ_f = ?10.8 ppm/°C.     

Bi4Ti3O12/TiO2 heterostructure: Synthesis,characterization and enhanced photocatalytic activity

A multicomponent oxide, Bi₄Ti₃O₁₂/TiO₂ heterostructure was successfully synthesized via a two-step synthesis route based on an anodic oxidation procedure and a subsequent hydrothermal technique. X-ray diffraction confirmed that the composition of the as-fabricated sample was a Bi₄Ti₃O₁₂/TiO₂ composite. Scanning and transmission electron microscopy observation reveals that the as-synthesized sample consisted of TiO₂ nanotubes decorated with Bi₄Ti₃O₁₂ nanocubes. The photocatalytic property of Bi₄Ti₃O₁₂/TiO₂ heterostructure was evaluated by decomposing methyl orange as a model organic compound. Compared with the unmodified TiO₂ nanotube arrays, Bi₄Ti₃O₁₂/TiO₂ heterostructure exhibits a higher photocatalytic activity in the decomposition of methyl orange under UV light. The prominent photocatalytic activity could be ascribed to the formation of the heterostructure between Bi₄Ti₃O₁₂ and TiO₂ as well as a good dispersity of Bi₄Ti₃O₁₂ nanocubes, which could effectively separate the photogenerated carriers and reduce the electron–hole recombination.     

Microstructural and Microwave Dielectric Properties of Bi12GeO20 and Bi2O3‐Deficient Bi12GeO20 Ceramics

Bi₁₂GeO₂₀ ceramics sintered at 800°C had dense microstructures, with an average grain size of 1.5 μm, a relative permittivity (ε_r) of 36.97, temperature coefficient of resonance frequency (τ_f) of ?32.803 ppm/°C, and quality factor (Q × f) of 3137 GHz. The Bi_12‐xGeO_20‐1.5x ceramics were well sintered at both 800°C and 825°C, with average grain sizes exceeding 100 μm for x ≤ 1.0. However, the grain size decreased for x > 1.0 because of the Bi₄Ge₃O₁₂ secondary phase that formed at the grain boundaries. Bi_12‐xGeO_20‐1.5x (x ≤ 1.0) ceramics showed increased Q × f values of >10 000 GHz, although the ε_r and τ_f values were similar to those of Bi₁₂GeO₂₀ ceramics. The increased Q × f value resulted from the increased grain size. In particular, the Bi_11.6GeO_19.4 ceramic sintered at 825°C for 3 h showed good microwave dielectric properties of ε_r = 37.81, τ_f = ?33.839 ppm/°C, and Q × f = 14 455 GHz.     

Optical properties and visible light-induced photocatalytic activity of bismuth sillenites (Bi12XO20, X = Si,Ge, Ti)

Three bismuth sillenite compounds with the general composition, Bi₁₂XO₂₀ (X = Si, Ge, Ti), were prepared by a conventional solid state synthesis route and their local crystal structure, light absorption and visible-light induced photocatalytic activities were systematically investigated. The prepared powder samples show comparable particle size distribution (~ 0.5–5 µm) and BET surface area (~ 0.8 m²/g). The optical band gap energies were estimated from diffuse reflectance spectra to be in the range 2.6–2.9 eV. The local crystal structure variation and its influence on the electronic band structure was elucidated in the three sillenite compounds by Raman analysis and density functional theory (DFT). The visible-light induced photocatalytic activity was evaluated by monitoring the degradation of rhodamine B dye solution under visible-light irradiation (> 420 nm). We found that the Bi₁₂TiO₂₀ powder shows the highest photocatalytic activity, which is attributed to the higher visible light absorption and the smaller band gap resulting from its distinct local crystal structure (longer Bi-O distance).     

片状铋/钒酸铋复合催化剂的制备及其光催化性能

用溶剂热法合成了一系列不同铋含量的片状铋/钒酸铋（Bi/BiVO₄）复合光催化剂。采用X射线衍射（XRD）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、紫外-可见漫反射光谱（UV-vis DRS）、电感耦合等离子发射光谱 （ICP-OES）、氮气吸附脱附和光电流响应等技术对所制备的催化剂进行了表征。通过氙灯下光催化降解亚甲基蓝的性能来评价样品的光催化活性,实验结果表明铋的自掺杂能显著提高钒酸铋的光催化活性。最后,通过自由基捕获实验对铋/钒酸铋光催化机理进行了探讨。     

Photoelectrochemical properties of Fe-doped TiO2 nanotube arrays fabricated by anodization

Ti–Fe alloys with Fe contents of 0.05, 0.5 and 1.0 wt% were obtained using the arc-melting method. Fe-doped TiO₂ nanotube arrays were prepared by anodizing Ti–Fe alloys in ethylene glycol solution containing 0.25 wt% NH₄F and 10 wt% H₂O. The microstructure, crystal structure and photoelectrochemical properties of the nanotube arrays were characterized using scanning electron microscopy, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy and electrochemical analyzer. Results show that doping of 0.05 wt% Fe improves the photoelectrochemical properties of titania nanotube arrays significantly, whilst further increasing the Fe contents to 0.5 and 1.0 wt% degrades these properties. The external potential has a considerable influence on the photocurrent density at doping content of 0.5 wt% Fe.     

铁掺杂钛酸铋钠钾陶瓷的制备及表征

采用传统固相法制备了无铅压电陶瓷Bi0.5(Na0.825K0.175)0.5TiO3+xFe2O3(x为质量分数,0、0.1%、0.3%、0.5%、0.7%、1.0%、1.5%)(简写BNKTF-x),利用X射线衍射(XRD),和扫描电子显微镜(SEM)等分析表征了该体系陶瓷的结构、介电与压电性能。XRD测试表明,在1 180℃、2 h的烧结条件下,当铁的质量分数小于1.0%时,陶瓷呈现单一相的钙钛矿结构。所有陶瓷晶粒大多呈四方晶形,晶界明显。增加铁的含量有利于晶粒生长。此外,铁的加入也使陶瓷样品气孔率降低,当铁的质量分数在0.3%左右时陶瓷的致密性最好。BNKTF-0.1%体系陶瓷具有较好的电学性能:d33=145 pC/N,kp=0.28,εr=869,tanδ=0.032,Qm=106。     

TiO2光催化膜的制备及其性能研究

采用溶胶-凝胶法制备了Ti O₂粉体,并以聚乙烯醇和聚多巴胺为载体,采用浇铸法制备出Ti O₂光催化薄膜。对膜的耐水性和光催化降解性能进行了测试。结果表明,光照30min甲基橙的降解率为89.33%,光照60min甲基橙的降解率为93%。随着薄膜内Ti O₂添加量的增加,膜的光催化性能逐渐增强,在水中的吸水率逐渐降低。     

纳米TiO2光催化剂的制备及其活性研究

采用溶胶-凝胶法制备了纳米TiO₂光催化剂，通过XRD表征产物的晶相结构。在单因素试验的基础上，用正交试验法对影响催化剂活性的条件进行了优化研究，结果表明，在焙烧温度600 ℃ 、焙烧时间2.5 h和V(醋酸)∶V(水)＝1∶1.67条件下，催化剂活性最大，对次甲基蓝的降解率可以达到85.4%。