TiO_2/Fe-杭锦2~#土催化剂光催化降解废水中乙酸的研究

首先采用离子交换法制得Fe-杭锦2#土,以其为载体使用溶胶-凝胶法制备了TiO_2/Fe-杭锦2#土负载型光催化剂,并通过X射线粉末衍射(XRD)、氮气吸附脱附(N2-BET)、固体紫外可见漫反射(UV-Vis DRS)、X射线光电能谱(XPS)和扫描电子显微镜(SEM)分析等对催化剂进行了表征.以光催化降解乙酸为探针反应,考察了Ti的负载量、光源、光照时间、催化剂用量和反应温度等反应条件对催化剂催化性能的影响.实验结果表明,对于浓度为100 mg·L-1的乙酸溶液,选用氧化钛负载量为20%的光催化剂、300 W汞灯为光源、反应温度为50℃、反应时间为6 h、催化剂用量为50 g·L~(-1)时,对乙酸的光催化降解效果相对最优,降解率达到78.30%.     

半导体光解水制氢研究:现状、挑战及展望

通过半导体光催化分解水反应实现太阳能向清洁能源氢能的转化,是解决人类面临的能源和环境危机的终极途径之一。该过程的关键是开发宽光谱响应、高效的光催化剂,到目前为止,调控能带结构、制备活性晶面、构建异质结构、负载助催化剂等诸多方法被广泛应用于扩展半导体材料的吸光范围和提高其光催化活性。本文介绍了半导体光解水制氢的基本原理,并综述了该领域的研究进展,重点关注提高半导体光催化活性的方法及其所面临的挑战和瓶颈问题,并结合相关课题组的研究工作提出可能的应对策略。     

p-n异质结BiPO_4/Ag_3PO_4的制备及其增强的模拟太阳光活性

采用一步水热合成法制备了BiPO_4、Ag_3PO_4和BiPO_4/Ag_3PO_4复合光催化剂,通过X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、紫外-可见漫反射(UV-Vis DRS)等表征手段对其组成结构、形貌及光吸收性质进行了表征,结果表明Ag_3PO_4呈块状结构,BiPO_4则分布在其表面,形成的BiPO_4/Ag_3PO_4复合光催化剂具有单斜相和立方晶相结构,带边吸收拓宽至571 nm。以甲基橙和加替沙星为目标污染物,考察了BiPO_4/Ag_3PO_4复合光催化剂在模拟太阳光照射下的降解矿化能力,结果表明复合催化剂比单一催化剂的降解矿化能力更强,稳定性更好。此外,自由基捕获实验表明空穴是该光催化过程中的主要活性物种,·O2-次之。p-n异质结的形成使BiPO_4/Ag_3PO_4复合光催化剂具有较强的电子空穴分离能力是光催化活性提高的主要原因,这与光电流和电化学阻抗谱测试结果相一致。基于以上结果,文中对BiPO_4/Ag_3PO_4光催化降解有机污染物的机理进行了推测。     

室温一步固相反应合成纳米氧化锌的表征、光催化性能及动力学

以七水硫酸锌、氢氧化钠为原料,采用室温一步固相反应合成ZnO纳米粒子,并分别利用X射线衍射分析（XRD）、傅里叶变换红外光谱分析（FTIR）、热重分析（TG）、扫描电子显微分析（SEM）、透射电子显微分析（TEM）、N₂吸附-脱附、紫外可见漫反射光谱分析（UV-Vis DRS）等方法对ZnO纳米粒子进行表征。实验结果表明：不需任何添加剂,室温下可通过一步固相反应合成ZnO纳米粒子,其形成过程首先是ZnSO₄·7H₂O和NaOH充分接触,然后反应形成Zn₄SO₄（OH）₆·5H₂O,最后NaOH的溶解热可使Zn₄SO₄（OH）₆·5H₂O转变为ZnO并逐渐长大形成纳米粒子。同时以甲基橙为降解对象评价了ZnO纳米粒子的光催化活性,实验结果表明：紫外光照射下,该方法合成的ZnO纳米粒子对甲基橙具有较好的光催化活性,且光催化动力学方程符合准一级反应动力学。     

添加NaBF_4对阳极氧化法制备TiO_2纳米管光催化剂的影响

在阳极氧化电解液中添加Na BF4制得了具可见光活性的B掺杂TiO_2纳米管阵列(B/TNTs)。采用扫描电镜(FE-SEM)、能谱仪(EDS)、X射线衍射(XRD)、傅立叶红外光谱(FTIR)、紫外-可见漫反射光谱(UV-Vis DRS)以及X射线光电子能谱(XPS)对样品进行表征,以亚甲基蓝(MB)的光催化降解为目标反应评价其光催化活性。结果表明:添加Na BF4后,TiO_2纳米管表面形貌变化较大;B掺入到TiO_2晶格中形成B-O-Ti键;B掺杂使得TiO_2纳米管表面羟基量增加、光学带隙能减小、光吸收阀值红移,且B掺杂量越多,其相应值的变化量越大;B掺杂能促进TiO_2锐钛矿相的发育,纳米管经550℃煅烧后仍保持未掺杂样品的锐钛矿相结构;Na BF4的最佳添加量为0.6%(w/w)时,所得样品光催化活性最佳,可见光下光催化降解MB的4 h降解率由未添加的39.90%提高至75.15%,且反复使用10次后其光催化性能基本保持不变;总有机碳(TOC)分析结果表明,MB在可见光下能被B/TiO_2有效矿化。     

Enhanced photocatalytic activity,mechanism and potential application of Idoped-Bi4Ti3O12 photocatalysts

In this study, we have introduced iodine into Bi₄Ti₃O₁₂ (BTO) crystals with the aim of improving their photocatalytic activities in decomposing organic pollutants. The as-prepared I_doped-BTO photocatalysts were systematically analyzed by various techniques (e.g. X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy), as well as density functional theory calculation. It is confirmed that I element is successfully doped, as an I^? oxidation state, in the BTO crystals by substituting the O in the perovskite-like (Bi₂Ti₃O₁₀)^2? blocks. The photocatalytic activities between the I_x-BTO (x = 0, 0.2, 0.4, 0.6, and 0.8) samples were compared by the photodegradation of methylene blue (MB) under simulated-sunlight irradiation, revealing that I_0.4-BTO is the optimal photocatalyst having a photocatalytic activity about 3.0 times higher than that of parent BTO. Based on the experimental data and density functional theory calculation, the enhanced photocatalytic mechanism for the I_doped-BTO photocatalysts was proposed and discussed. To promote the potential application of the optimal I_0.4-BTO photocatalyst, its photocatalytic performances were further investigated by the photodegradation of ciprofloxacin, tetrabromobisphenol A, tetracycline hydrochloride and methyl orange/rhodamine B (RhB)/MB mixture dyes; moreover, the effect of inorganic anions and pH values on the MB photodegradation was also investigated.     

K/Cl掺杂g-C_(3)N_(4)的制备及其光催化性能研究北大核心CSCD

采用湿化学方法制备了K/Cl掺杂石墨相氮化碳(g-C_(3)N_(4))纳米材料.以三聚氰胺、KCl作为前驱体,经过溶解、沉淀和焙烧过程,使K/Cl元素在g-C_(3)N_(4)结构上均匀分布.K/Cl掺杂的引入并不影响g-C_(3)N_(4)物相的形成,而是使样品的比表面积增加至18.36 m^(2)·g^(-1),是纯g-C_(3)N_(4)的1.7倍.利用光催化降解气态污染物来表征材料的光催化性能,结果表明,全光谱光照下CN-K/Cl-0.07的性能是纯g-C_(3)N_(4)的2.0倍.光催化性能的提升归因于K/Cl双原子掺杂,不但提升了材料的光吸收能力,而且有利于光生电子-空穴的分离.4次循环试验后,CN-K/Cl-0.07光催化降解异丙醇的性能没有明显降低,证明其具有良好的稳定性.K/Cl掺杂g-C_(3)N_(4)光催化活性高且使用性能好,将会在气体污染物降解领域产生广泛的应用.     

Parasitic Light Absorption,Rate Laws and Heterojunctions in the Photocatalytic Oxidation of Arsenic(III) Using Composite TiO2/Fe2O3

Composite photocatalyst-adsorbents such as TiO₂/Fe₂O₃ are promising materials for the one-step treatment of arsenite contaminated water. However, no previous study has investigated how coupling TiO₂ with Fe₂O₃ influences the photocatalytic oxidation of arsenic(III). Herein, we develop new hybrid experiment/modelling approaches to study light absorption, charge carrier behaviour and changes in the rate law of the TiO₂/Fe₂O₃ system, using UV-Vis spectroscopy, transient absorption spectroscopy (TAS), and kinetic analysis. Whilst coupling TiO₂ with Fe₂O₃ improves total arsenic removal by adsorption, oxidation rates significantly decrease (up to a factor of 60), primarily due to the parasitic absorption of light by Fe₂O₃ (88 % of photons at 368 nm) and secondly due to changes in the rate law from disguised zero-order kinetics to first-order kinetics. Charge transfer across this TiO₂-Fe₂O₃ heterojunction is not observed. Our study demonstrates the first application of a multi-adsorbate surface complexation model (SCM) towards describing As(III) oxidation kinetics which, unlike Langmuir-Hinshelwood kinetics, includes the competitive adsorption of As(V). We further highlight the importance of parasitic light absorption and catalyst fouling when designing heterogeneous photocatalysts for As(III) remediation.     

C/Cr2O3/TiO2复合材料的制备及其光催化性能研究

本文以制革含铬革屑为原材料,基于矿物鞣剂复鞣的原理,将Ti(IV)均匀、稳定地负载到含铬革屑上,在氮气氛围下,经高温热解制备得到C/Cr₂O₃/TiO₂光催化剂,并研究了其对四环素(TC)的光催化降解效果及机理。结果表明,C/Cr₂O₃/TiO₂光催化剂具有明显的介孔结构,比表面积较大,为277.47 m²·g^-1,Cr₂O₃和TiO₂已实现复合并负载在生物炭(C)上。通过光催化降解发现,在模拟自然光照下,当催化剂用量为0.04 g,TC初始浓度为50 mg·L^-1,溶液pH为2时,TC的去除率可高达99.99%。结合自由基捕获实验发现,C/Cr₂O₃/TiO₂光催化剂对TC的降解作用主要依靠反应体系中产生的大量·O₂^-,·OH和h⁺。     

改性二氧化钛纳米棒的制备及光催化有机污染物研究

为了改善纳米二氧化钛的光催化活性,通过水热法制备了氮钨共掺杂二氧化钛纳米棒。通过扫描电镜(SEM),X射线衍射(XRD),透射电镜(TEM),X射线光电子能谱(XPS)和紫外可见光吸收光谱 (UV-VIS)等对产物进行了相关表征。结果显示：与未掺杂的二氧化钛相比,氮钨共掺杂的二氧化钛纳米棒在可见光区域显示出了较强的光催化活性。因为氮钨阳离子的掺入拓宽了可见光的吸收区域。