不同氮源溶剂热合成N-TiO2纳米颗粒及其光催化降解气相苯（英文）

采用三种不同的氮源溶剂热合成了锐钛矿-板钛矿混晶的N-TiO2催化剂.采用X射线衍射、N2吸附-脱附、X射线光电子能谱和透射电子显微镜等手段对催化剂进行了表征.重点研究了不同氮源对催化剂的相组成、晶粒尺寸、微观结构以及比表面积的影响.采用紫外光降解气相苯测试了合成材料的催化活性.结果表明,以水合肼为氮源合成的N-TiO2表现出最优的光催化活性,其活性明显高于P25,且能够循环使用15次以上.采用气相色谱-质谱技术分析了光降解过程的中间产物,基于此提出了相应的降解机理.     

H3PW12O40掺杂TiO2介孔材料的制备及光催化性能

以P123为模板剂,采用溶胶-凝胶的溶剂热合成方法制备了H3PW12O40掺杂TiO2介孔材料H3PW12O40/TiO2.利用紫外可见漫反射吸收光谱(UV-vis/DRS)、X射线粉末衍射(XRD)、N2吸附和透射电子显微镜(TEM)手段对所制备的材料进行结构表征,罗丹明B(RB)为模型污染物评价其光催化性能.结果表明,所制备的介孔材料具有锐钛矿与板钛矿复合的晶型结构、大的BET比表面积和孔径均匀分布的介孔结构.光催化实验表明,H3PW12O40/TiO2可将罗丹明B完全矿化.     

纳米SiC基光催化剂研究进展

Industrialization undoubtedly boosts economic development and improves the standard of living; however, it also leads to some serious problems, including the energy crisis, environmental pollution, and global warming. These problems are associated with or caused by the high carbon dioxide (CO₂) and sulfur dioxide (SO₂) emissions from the burning of fossil fuels such as coal, oil, and gas. Photocatalysis is considered one of the most promising technologies for eliminating these problems because of the possibility of converting CO₂ into hydrocarbon fuels and other valuable chemicals using solar energy, hydrogen (H₂) production from water (H₂O) electrolysis, and degradation of pollutants. Among the various photocatalysts, silicon carbide (SiC) has great potential in the fields of photocatalysis, photoelectrocatalysis, and electrocatalysis because of its good electrical properties and photoelectrochemistry. This review is divided into six sections: introduction, fundamentals of nanostructured SiC, synthesis methods for obtaining nanostructured SiC photocatalysts, strategies for improving the activity of nanostructured SiC photocatalysts, applications of nanostructured SiC photocatalysts, and conclusions and prospects. The fundamentals of nanostructured SiC include its physicochemical characteristics. It possesses a range of unique physical properties, such as extreme hardness, high mechanical stability at high temperatures, a low thermal expansion coefficient, wide bandgap, and superior thermal conductivity. It also possesses exceptional chemical characteristics, such as high oxidation and corrosion resistance. The synthesis methods for obtaining nanostructured SiC have been systematically summarized as follows: Template growth, sol-gel, organic precursor pyrolysis, solvothermal synthesis, arc discharge, carbon thermal reduction, and electrospinning. These synthesis methods require high temperatures, and the reaction mechanism involves SiC formation via the reaction between carbon and silicon oxide. In the section of the review involving the strategies for improving the activity of nanostructured SiC photocatalysts, seven strategies are discussed, viz., element doping, construction of Z-scheme (or S-scheme) systems, supported co-catalysts, visible photosensitization, construction of semiconductor heterojunctions, supported carbon materials, and construction of nanostructures. All of these strategies, except element doping and visible photosensitization, concentrate on enhancing the separation of holes and electrons, while suppressing their recombination, thus improving the photocatalytic performance of the nanostructured SiC photocatalysts. Regarding the element doping and visible photosensitization strategies, element doping can narrow the bandgap of SiC, which generates more holes and electrons to improve photocatalytic activity. On the other hand, the principle of visible photosensitization is that photo-induced electrons move from photosensitizers to the conduction band of SiC to participate in the reaction, thus enhancing the photocatalytic performance. In the section on the applications of nanostructured SiC, photocatalytic H₂ production, pollutant degradation, CO₂ reduction, photoelectrocatalytic, and electrocatalytic applications will be discussed. The mechanism of a photocatalytic reaction requires the SiC photocatalyst to produce photo-induced electrons and holes during irradiation, which participate in the photocatalytic reaction. For example, photo-induced electrons can transform protons into H₂, as well as CO₂ into methane, methanol, or formic acid. Furthermore, photo-induced holes can convert organic waste into H₂O and CO₂. For photoelectrocatalytic and electrocatalytic applications, SiC is used as a catalyst under high temperatures and highly acidic or basic environments because of its remarkable physicochemical characteristics, including low thermal expansion, superior thermal conductivity, and high oxidation and corrosion resistance. The last section of the review will reveal the major obstacles impeding the industrial application of nanostructured SiC photocatalysts, such as insufficient visible absorption, slow reaction kinetics, and hard fabrication, as well as provide some ideas on how to overcome these obstacles.      

BiOBr/CeO2复合材料的制备及光催化降解磺胺异恶唑

通过高温煅烧法和共沉淀法成功制备BiOBr/CeO₂复合材料,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和比表面积孔径分析仪(BET)等手段对光催化材料进行表征,并将该复合材料用于光催化降解磺胺异恶唑。 研究表明, BiOBr/CeO₂对可见光有更高的吸收性能,比CeO₂和BiOBr具有更强的降解效率。 自由基捕获实验证明,催化剂降解过程中起主要作用的活性基团是·O^-₂和h⁺。 CeO₂的复合提高了材料的光利用效率,能够促进光生电荷分离,进而提高材料的光催化活性。 回收再利用实验表明,BiOBr/CeO₂ 复合材料具备较好的稳定性,循环3次后催化活性无明显衰减。     

纳米SiC基光催化剂研究进展

工业化无疑促进了经济的发展,提高了生活水平,但也导致了一些问题,包括能源危机、环境污染、全球变暖等, 其中这些所产生问题主要是由燃烧煤炭、石油和天然气等化石燃料引起的。光催化技术具有利用太阳能将二氧化碳转化为碳氢化合物燃料、从水中制氢、降解污染物等优点,从而在解决能源危机的同时避免环境污染,因此被认为是解决这些问题的最有潜力的技术之一。在各种光催化剂中,碳化硅(SiC)由于其优良的电学性能和光电化学性质,在光催化、光电催化、电催化等领域具有广阔的应用前景。本文首先系统地阐述了各种SiC的合成方法,具体包括模板生长法、溶胶凝胶法、有机前驱物热解法、溶剂热合成法、电弧放电法,碳热还原法和静电纺丝等方法。然后详细地总结了提升SiC光催化活性的各种改性策略,如元素掺杂、构建Z型(S型)体系、负载助催化剂、可见光敏化、构建半导体异质结、负载炭材料、构建纳米结构等。最后重点论述了半导体的光催化机理以及SiC复合物在光催化产氢、污染物降解和CO₂还原等领域的应用研究进展,并提出了前景展望。     

灭多威的光催化降解动力学研究

研究了农药灭多威在ＴｉＯ２光催化下的降解产物,反应动力学及影响降解速度的因素,灭多威在ＴｉＯ２催化下１０ｍｉｎ内可被完全转换为无机物而失去毒害作用,ＩＲ研究表明,灭多威的分解产物ＮＨ＾＋４,ＳＯ＾２－４和ＣＯ２,其分争过程中准一级反应,除铜和氯离子体低浓度时有促进作用,而高浓度为阻碍作用外,大部分阴,阳离子对降解均有不利影响。     

离子交换法制备高光催化活性Bi2WO6@Bi2S3异质结纳米片

社会经济快速发展的同时, 也带来了日益严峻的环境污染问题. 半导体光催化氧化技术因节能环保而在环境领域有广阔的应用前景. 作为最具有代表性的半导体光催化材料, TiO2因为其禁带宽度(3.2 eV)比较大, 只能被紫外光激发, 因而对太阳能的利用率较低. 作为一种最简单的含铋层状氧化物, Bi2WO6的禁带宽度(2.7 eV)相对较小, 可以部分利用太阳光中的可见光, 因而受到广大研究者的青睐. 但是, Bi2WO6光催化材料的可见光响应范围较窄, 仅能被波长小于450 nm的光激发, 且激发后的光生载流子容易复合, 导致光催化效率不高. 因此, 迫切需要对Bi2WO6光催化材料进行结构修饰与改性,采用拓展其光响应范围和抑制载流子复合, 来提高其光催化活性.本文采用离子交换法原位合成了具有核-壳结构的Bi2S3@Bi2WO6纳米片, 充分利用Bi2S3优良的可见光响应性能和半导体异质结光催化剂的构建, 来提高Bi2WO6的光催化活性. 结果表明, 随着Na2S·9H2O用量从0增加到1.5 g, 所得催化剂的光活性不断提高, X3B的降解速率常数由0.40×10-3min-1增加到6.6×10-3min-1, 催化剂活性提高了16.5倍. 当进一步增加Na2S·9H2O的用量时(1.5-3.0 g), 复合催化剂的光活性下降. 这是由于过多Na2S·9H2O的引入导致在催化剂表面生成了没有光活性的NaBiS2层(Bi2S3+ Na2S = 2NaBiS2), 占据了催化剂的活性位点, 阻碍了染料分子与催化剂的直接接触. Bi2WO6@Bi2S3异质结纳米片光活性的提高, 可归因于Bi2S3的敏化作用极大拓展了复合催化剂的光响应范围; 另一方面, Bi2WO6和Bi2S3两者之间的半导体异质结效应有效促进了光生载流子在空间的有效分离, 抑制了光生电子-空穴的复合, 从而提高了复合催化剂的催化效率. 本研究为其他半导体复合材料的原位生长制备提供了新的思路.     

Efficient photocatalytic degradation of methyl orange dye using facilely synthesized α-Fe2O3 nanoparticles

In this paper, α-Fe₂O₃ nanoparticles were fabricated via the combustion process using glucose and sucrose as organic fuels for the first time. The fabricated products were characterized using XRD, FT-IR, HR-TEM, and UV–vis spectrophotometer. The average crystallite size of the α-Fe₂O₃ samples, which were synthesized using glucose and sucrose fuels, is 27.25 and 6.13 nm, respectively. The HR-TEM images confirmed the presence of spherical and irregular shapes with an average diameter of 31.92 and 8.83 nm for the α-Fe₂O₃ samples, which were synthesized using glucose and sucrose fuels, respectively. The optical energy gap of the α-Fe₂O₃ samples, which were synthesized using glucose and sucrose fuels, is 2.00 and 2.48 eV, respectively. Additionally, the synthesized α-Fe₂O₃ samples were employed as a photocatalyst for the degradation of methyl orange dye under UV irradiations in the absence and presence of hydrogen peroxide. The optimum pH, irradiation time, and dose of α-Fe₂O₃ that achieved the highest degradation efficiency in the presence of hydrogen peroxide (82.17 % in the case of using an α-Fe₂O₃ sample which was synthesized using glucose or 95.31 % in the case of using an α-Fe₂O₃ sample which was synthesized using sucrose) are 3, 100 min, and 0.05 g, respectively.     

蛋氨酸改性TiO2空心纳米盒高效可见光催化RhB分解和NO氧化

由高能面 TiO2纳米片 (TiO2-NSs) 组装成的 TiO2空心纳米盒 (TiO2-HNBs)显示出比单独 TiO2-NSs 更强的光催化性能, 但是 TiO2-HNBs 依然属于紫外光催化剂, 无法充分利用太阳能. 因此, 开发具有可见光响应的由高能面 TiO2-NSs 组装而成的 TiO2-HNBs 具有重要意义. 本文将立方体 TiOF2与含有 N 和 S 元素的生物分子蛋氨酸混合, 通过一步焙烧制备了具有可见光响应活性的 N 和 S 元素共掺杂的 TiO2-HNBs(掺杂催化剂标记为 TMx, 未掺杂催化剂标记为 Tx, x 代表焙烧温度).由立方体 TiOF2到锐钛矿相 TiO2空心纳米盒的转变是一个自模板转化过程. 氟离子的存在降低了 TiO2高能面(001)面的表面能, 从而使得高能面 TiO2纳米片的形成变得可能. 因此, 热处理立方体 TiOF2可得到由高能面 TiO2纳米片组装的 TiO2空心纳米盒.本文系统研究了焙烧温度 (300-500 ℃) 对所制 TiO2-HNBs 结构与光催化性能的影响. 结果发现, 在 350 ℃下焙烧, TiOF2完全转化成锐钛矿相 TiO2-HNBs. 但是焙烧蛋氨酸与 TiOF2的混合物, 需 400 ℃才能完全实现 TiOF2到锐钛矿相TiO2-HNBs 的转变. 这说明蛋氨酸的加入阻碍了 TiOF2向锐钛矿相 TiO2-HNBs 的转变. XPS 结果显示, 经过 400 ℃焙烧的蛋氨酸改性样品 (TM400), N 和 S 元素成功掺入了 TiO2-HNBs 晶格, 使其产生可见光催化活性.相对于 400 ℃焙烧 TiOF2所得样品 T400, 蛋氨酸改性的 TM400 催化剂可见光降解罗丹明 B 染料 (RhB) 和 NO 氧化的性能分别提升了 1.55 倍和 2.0 倍, 这与其更强的可见光吸收性能和光生载流子分离效率有关. 400 ℃焙烧的蛋氨酸改性的 TM400 可见光催化活性稳定, 连续 5 次可见光催化 RhB 降解后, 其活性没有明显改变, 显示了潜在的应用前景.     

Photocatalytic activity and biodegradation of polyhydroxybutyrate films containing titanium dioxide

This study aims to evaluate the photocatalytic activity and biodegradation of polyhydroxybutyrate (PHB) films containing titanium dioxide (TiO₂). Nanosized TiO₂ photocatalysts were immobilized onto PHB film to overcome the difficulty of the recovery process. PHB is a suitable base material as it is naturally biodegradable and is produced from renewable resources. The photocatalytic degradation of organic compounds, photocatalytic sterilization activity and biodegradation rate in garden soil of PHB-TiO₂ composite films were investigated. After an hour under solar illumination, 96% of methylene blue solution was decolorized. The antibacterial activity against Escherichia coli (E. coli) using PHB-TiO₂ composite film exhibited enhanced photocatalytic sterilization activity over time. As for the ability to biodegrade, PHB-TiO₂ composite films placed on soil surface with no direct solar illumination showed slower degradation rate compared to those receiving direct solar illumination. Interestingly, the latter composite films showed faster degradation rates compared to pure PHB films indicating that the degradation is mainly due to photocatalytic activity. PHB-TiO₂ composite films buried in soil generally showed slower degradation rates compared to pure PHB films and were dependent on the soil microbial activity.     

Preparation Bi2S3-TiO2 heterojunction/polymer ?ber composites and its photocatalytic degradation of methylene blue under Xe lamp irradiation

This paper presented the preparation of Bi₂S₃-TiO₂ heterojunction/polymer ?ber composites and their performance of the degradation of methylene blue using Xe lamp irradiation. The polysulphone (PSU)/styrene-maleic anhydride copolymer (SMA) ?bers were prepared by electrospinning. Bismuth ions were introduced onto the surface of polymer ?ber by the coordinating of carboxyl of SMA, sul?de ions were incorporated to react with bismuth ions under hydrothermal condition. TiO₂ was deposited on the surface of the Bi₂S₃ by the reaction of titanium ions with urea also under hydrothermal condition. Scanning electron microscopy (SEM) and high resolution transmission electron microscope (HRTEM) images revealed that Bi₂S₃-TiO₂ heterojunction was uniformly distributed on the surface of PSU/SMA ?bers. The ultraviolet-visible absorption spectra (UV/VIS) showed that the Bi₂S₃-TiO₂ heterojunction/polymer ?ber composites possess good visible-light response ability. The degradation rate of methylene blue in Bi₂S₃-TiO₂ heterojunction/polymer ?ber composites system was considerably higher than that of Degussa P25 or Bi₂S₃-TiO₂ heterojunction system under Xe lamp irradiation.     

水中硝基酚的纳米TiO_2光催化降解

以主波长254nm的紫外灯作为光源,研究了锐钛型纳米TiO2对邻硝基苯酚、2,4－二硝基苯酚的光催化降解行为,并与普通TiO2作了对比;结果表明,纳米TiO2表现出很高的光催化活性,催化降解过程符合一级动力学规律。     

网络状纳米氧化锌光催化降解水中有机染料的研究

在太阳光照射条件下用自制的网络状纳米氧化锌对不同有机染料溶液的降解性能作了系统的研究。结果表明,网络状纳米氧化锌对弱碱性有机染料溶液的降解效果较好。本文还比较了自制网络状纳米氧化锌与纳米二氧化钛对有机染料的降解性能,氧化锌的降解效果明显优于二氧化钛。