Ag纳米粒子在TiO2四棱柱阵列上的可控生长及其SERS效应

采用水热法在导电玻璃FTO导电面上沉积TiO₂四棱柱阵列; 并以其为基体, 分别采用聚乙烯基吡咯 烷酮(PVP)还原Tollens试剂以及柠檬酸三钠(TSC)还原硝酸银溶液, 将Ag纳米粒子(AgNPs)沉积在TiO₂四棱柱阵列上形成TiO₂@AgNPs-PVP和TiO₂@AgNPs-TSC微纳结构作为表面增强拉曼散射(SERS)基底. 实验结果表明, Ag纳米粒子在TiO₂四棱柱阵列上的尺寸和分布可通过改变Tollens试剂的浓度和TSC还原硝酸银溶液的反应时间来调控, 进而优化基底的SERS灵敏度. TiO₂@AgNPs-PVP微纳结构对罗丹明6G(R6G)的检出限为10^-12 mol/L, 对低活性小分子三聚氰胺的检出限为0.01 mg/mL; TiO₂@AgNPs-TSC微纳结构对R6G的检出限为10^-10 mol/L, 对三聚氰胺的检出限为0.01 mg/mL. TiO₂@AgNPs-PVP和TiO₂@AgNPs-TSC微纳结构基底的SERS活性、 循环可回收性与还原剂种类紧密相关: 包覆在Ag纳米粒子上的PVP可以作为隔离层避免Ag纳米粒子直接接触, 防止电磁场耦合作用减弱, 增强基底的SERS活性; 同时, PVP是一种水性聚合物, 有较强的亲水性, 作为循环可回收SERS基底使用时, 吸附小分子物质清洗难度较大.     

聚丙烯酸在纳米TiO2表面吸附行为的研究

讨论了聚丙烯酸在纳米TiO₂水悬浮体系中的吸附行为.红外光谱分析和吸附实验结果表明,纳米TiO₂通过氢键吸附PAA.PAA吸附量随着浓度的升高而增大直至饱和吸附量,且分子量越大,饱和吸附量越大.pH值增大,则饱和吸附量减小.在相同条件下,表面吸附层的厚度随PAA分子量、浓度和pH值增大而增大.这是由PAA在颗粒表面构型的变化所致.吸附PAA后的纳米TiO₂的表面电荷密度和ζ电位发生变化,pHiep值向低值方向移动.表面吸附自由能的计算结果说明,PAA在纳米TiO₂表面的吸附是自发过程.     

TiO2-CeO2光催化吸附协同脱除柴油中的有机硫

采用共沉淀法制备TiO₂-CeO₂光催化吸附脱硫材料,通过低温N₂吸附脱附和X射线衍射等技术对TiO₂-CeO₂的物理化学性质进行了表征。结果表明,紫外光辐射显著提高了TiO₂-CeO₂的吸附脱硫性能;柴油中有机硫在TiO₂-CeO₂表面发生了光催化氧化转化为极性较强的砜类,可选择性地吸附在材料表面而被脱除。当TiO₂-CeO₂材料中钛铈物质的量比为9：1、煅烧温度为500℃时,其光催化吸附协同脱硫效果最好;在紫外光辐射下反应5 h,油品中DBT的脱除率高达99.6%。TiO₂-CeO₂光催化吸附协同脱硫工艺可有效解决吸附脱硫工艺中芳烃竞争吸附导致吸附脱硫选择性低的问题;在模拟油品中添加质量分数为25%的甲苯,反应7 h后油品脱硫率仍高达96.6%。TiO₂-CeO₂对不同硫化物的光催化吸附协同脱硫效果顺序为：4,6-DMDBT> DBT> BT。TiO₂-CeO₂经四次再生循环使用后,脱硫率没有明显降低。     

电解质对TiO2纳米管阵列膜光生阴极保护效应的影响

基于光电化学测试考察了光电解池中电解质(NaNO₃, NaCl, Na₂SO₄, Na₂S和NaOH)的种类和浓度对阳极氧化法制备的锐钛矿型TiO₂膜电极光电性能的影响, 并解释了其作用机理.结果表明, 电解质捕获空穴的能力顺序为Na₂S>NaOH>Na₂SO₄>NaCl>NaNO₃.Na₂S和NaOH在溶液中具有协同作用, 当两者组成混合溶液并且浓度均为0.5 mol/L时, 更有利于TiO₂膜光生电子-空穴对的分离和光电转化性能的提高.当0.5 mol/L NaCl溶液中的403不锈钢(403SS)与0.5 mol/L Na₂S+0.5 mol/L NaOH混合溶液中的TiO₂膜电极耦连时, 光照膜电极可使403SS的电极电位负移约650 mV, 具有良好的光生阴极保护效应.当切断光源时, 在该混合液中TiO₂膜也能对403SS起到一定的阴极保护作用.     

H2O2/TiO2超声协同光降解活性艳橙的研究

以活性艳橙溶液为模拟废水,通过H₂O₂/TiO₂超声(US)协同作用光降解活性艳橙溶液,探讨了TiO₂催化剂用量、H₂O₂用量、活性艳橙溶液的初始浓度、pH值、TiO₂催化剂锻烧温度等对活性艳橙溶液降解率的影响,并比较了几种不同作用方式对活性艳橙溶液的降解效果.结果表明:UV/H₂O₂/TiO₂/US协同作用降解活性艳橙溶液的效果最好;当活性艳橙溶液的初始浓度为20 mg·L^-1,pH＝5,TiO₂用量为0.4 g·L^-1,H₂O₂用量为0.4 ml·L^-1时,降解率可达92.06%.     

TiO2掺杂用于调变α-Al2O3中空纤维膜烧结性能与表面性质

利用相转化?高温烧结技术制备α?Al₂O₃中空纤维膜,系统研究了TiO₂掺杂调变中空纤维膜的烧结性能与表面性质。结果表明,TiO₂与α?Al₂O₃之间的固相反应能够促进中空纤维的烧结,当TiO₂掺杂量(物质的量分数)为1%~2%时,其烧结温度可以降到1400℃,且机械强度保持不变;TiO₂掺杂增加了中空纤维表面的羟基活性位点浓度,从而有利于CHA分子筛膜的生长;使用物质的量分数1%~3%TiO₂掺杂的α?Al₂O₃中空纤维制备出高质量CHA分子筛膜,其用于乙醇/水(9∶1,w/w)溶液渗透汽化脱水时的分离因子均超过10000。     

在玻璃的TiO2涂膜上有机物分子的吸附及光催化分解对水接触角的影响

研究了有机物分子在玻璃的TiO₂ 和WO₃/TiO₂ 复合物涂膜上的吸附及光催化分解对水接触角的影响.结果表明:有机物在空白玻璃及其膜的表面的吸附为不可逆化学吸附,WO₃/TiO₂ 复合物膜可钝化玻璃表面对大气污染物分子的吸附能力并具有较好的光催化活性.     

菲在TiO2催化下的光降解研究

以汞灯为光源,TiO₂为催化剂,对菲的光催化降解途径进行了研究.将水溶性极小的菲预先吸附到TiO₂上之后,菲可以在紫外线的照射下发生快速、完全的矿化.通过GC-MS手段检测到一些中间产物,给出了菲光催化降解的详细途径.另外,研究了菲在表面活性剂十六烷基三甲基溴化铵(HTAB)的助溶下TiO₂催化的光降解过程,探讨了表面活性剂的浓度和溶液pH值对反应速率的影响.     

调控金纳米花表面凸起的策略及其表面增强拉曼散射活性

以聚乙烯吡咯烷酮(PVP)与十二烷基硫酸钠(SDS)通过阳离子架桥形成的拟聚阴离子为软模板,通过改变PVP、SDS和纳米材料前驱体氯金酸(HAu Cl₄)浓度以及反应时间等因素,调控还原产物金纳米花形貌及粒径。表面张力、电导率、毛细管电泳及Zeta电位等实验结果表明PVP-SDS-HAu Cl₄形成新的拟聚阴离子,透射电子显微镜和X射线衍射结果表明SDS、PVP和HAu Cl₄的较低浓度组合更易获得表面凸起丰富的金纳米花。PVP-SDS拟聚阴离子发挥了二级软模板作用,在PVP (50 g·L^-1)-SDS (2 mmol·L^-1)-HAu Cl₄ (0.25 mmol·L^-1)溶液中调控合成的金纳米花为{111}晶面为主的面心立方结构,其平均等效粒径为108 nm,且表面上密集分布约16.5 nm的凸起。该金纳米花有较强的表面增强拉曼散射(SERS)活性,探针分子罗丹明6G的SERS信号强度依赖于金纳米花的表面凸起形貌。该研究中金纳米...     

介孔TiO2对溶菌酶吸附的动力学和热力学

773.15 K下焙烧二钛酸(H₂Ti₂0₅)制备了介孔结构TiO₂。采用比表面分析仪(BET)、扫描电镜(SEM)、拉曼(Raman)光谱和X射线衍射(XRD)仪进行表征研究了介孔TiO₂对溶菌酶的吸附行为和机理。结果表明,该吸附过程较好地满足Langmuir吸附模型;随着溶液pH值的增高,溶菌酶在介孔TiO₂上的吸附量先增大后减小。在pH = 7.2时,达到最大吸附容量72.5 mg·g^-1。该介孔TiO₂对溶菌酶具有良好的吸附稳定性,经过5次循环后吸附的溶菌酶残余量仍有81.6%。动力学研究表明,介孔TiO₂与溶菌酶间的吸附满足准二级动力学模型,吸附传质过程由膜扩散和粒内扩散共同影响与控制。对热力学参数的计算发现,该过程ΔG⁰ < 0, ΔH⁰ > 0, ΔS⁰ > 0,表明介孔TiO₂对溶菌酶的吸附是一个自发的、吸热的熵增过程。     

表面活性剂对TiO2水悬浮体稳定及流变性质的影响

在陶瓷的制备过程中,通常需将陶瓷粉末分散于水中形成陶瓷浆后再浇铸成型.研究表明[1],陶瓷浆的分散、稳定及流变性质直接影响到成品的性能.因此,研究分散稳定剂对该浆料性质的影响有着重要意义.本文利用电泳和流变学方法研究了TiO2在表面活性剂的水溶液中浓浆体的分散稳定性及流变性质.     

High-performance titanium dioxide photocatalyst on ordered mesoporous carbon support

Anatase TiO₂ photocatalysts supported with the ordered mesoporous carbon, CMK-3, were synthesized by the incorporation of TiO₂ into CMK-3 followed by heating at 700 °C. The structural properties of the TiO₂ on CMK-3 were investigated by X-ray diffraction, nitrogen physisorption and electron microscopy techniques. In particular, TiO₂ was observed both inside and the external surface of CMK-3. The photocatalytic activity of TiO₂ on CMK-3 under UV-light exhibited higher efficiency in removing the Rhodamine 6G dye solution than the commercial photocatalyst P25 and TiO₂ on activated carbon. It was attributed to the synergistic effect of large surface area adsorption provided by mesoporous CMK-3 and the distinctive location of TiO₂ on the external surface of CMK-3.     

Adsorption of tricarboxylic acid biosurfactant derived from spiculisporic acid on titanium dioxide surface

In the present study, adsorption isotherms of a polycarboxylic-acid-type biosurfantant, the sodium salt of (2-(2-carboxyethyl)-3-decyl maleic anhydride) (DCMA-3Na), on TiO₂, zeta potential, and changes in particle aggregate size as a function of biosurfactant concentration, solid-liquid ratio and pH were systematically investigated. The adsorption of DCMA-3Na on the surface of TiO₂ shows a relatively weak dependence on pH, unlike the adsorption behavior of chemically-synthesized surfactants. Adsorption of DCMA-3Na still occurs at pH above the isoelectric points of TiO₂ due to the buffering capacity, which is due to three carboxylate functional groups in the hydrophilic moiety of DCMA-3Na. Since DCMA-3Na has three anionic head groups, the zeta potential of TiO₂ at pH 3 decreases very steeply from positive to negative values as the surface charges are neutralized by the adsorption of biosurfactants. Trends in zeta potentials as a function of equilibrium DCMA-3Na concentration are quite closely related to the changes in flocculation of individual TiO₂ particles.     

Boosting sodium storage of mesoporous TiO2 nanostructure regulated by carbon quantum dots

It has been demonstrated that the conductivity and electrochemical properties of TiO2 nanomate rials can be significantly improved by an incorporation of carbon additives.In the study,we develop a novel Ndoped TiO2 mesoporous nanostructure via the addition of carbon quantum dots(CQDs)solution following a scalable hydrothermal process.The as-made TiO2 product shows well-defined morphology,high conductivity,large surface area,and abundant mesopores.When evaluated as anodes for sodiumion batteries,the CQDs@TiO2 product annealed at 500℃exhibits a superior sodium storage capability.It delivers a high reversible capacity of 168.8 mAh/g at 100 mA/g over 500 cycles and long cycling stability.The remarkable performance of CQDs@TiO2 mainly arises from the large surface area and mesoporous architecture constructed by ultrathin TiO2 nanosheets,as well as the full coope ration between CQDs and TiO2.     

Foam-structured Activated Carbon-ceramic as TiO2 Supports for Photocatalytic Degradation of Phenol

An activated foam-structured carbon-ceramic(AFCC) was prepared and investigated as TiO₂ support for the photocatalytic degradation of phenol. AFCC and TiO₂/AFCC catalysts were characterized by N₂ adsorption- desorption and X-ray diffraction(XRD). The effects of AFCC on the photocatalytic activity and the crystallinity of TiO₂ were studied. The results show that the crystallinity and anatase/rutile ratio of TiO₂ loaded on AFCC could be significantly influenced by the calcination temperature. The degradation rate of phenol benefited from the synergistic effects of the adsorption of activated carbon(AC) and the photocatalysis of TiO₂, which suggests that a high surface area of AC is essential to achieve high degradation rates and efficiencies. It was found that the larger mean cell size of AFCC increased the light transmission within the foam.     

碳包覆Pd/TiO2光催化产氢协同胺类选择性氧化合成亚胺(英文)

负载型金属纳米催化剂由于其优异的光催化性能,被广泛应用于光催化产氢协同胺类氧化偶联合成高附加值亚胺体系。但在反应过程中,金属表面对H原子和亚胺表现出较强的吸附能力,导致了亚胺易于发生自氢化反应而生成仲胺,显著降低了亚胺的选择性。在本文中,我们证实了在Pd/Ti O₂表面构建超薄碳层(Pd/Ti O₂@C)是一种解决上述问题的有效策略。在Pd/Ti O₂表面构筑的超薄碳层可以有效调控H原子和亚胺在其表面的吸附行为,避免了光催化氧化偶联过程中亚胺的自氢化。因此,Pd/Ti O₂@C光催化剂在光催化产氢协同胺类选择性氧化合成亚胺体系中展现出优异的亚胺选择性。本研究提供了一种便捷有效的策略推动负载型金属纳米催化剂在光催化产氢协同合成高附加值产物体系中的应用。     

Photocatalytic degradation of hydrocarbons by bentonite and TiO2 in aqueous suspensions containing surfactants

Organic substances (toluene, asphaltene dissolved in toluene) poorly soluble in water were solubilized by sodium dodecylsulfate (SDS) and the organic pollutants were mineralized together with the surfactants in diluted TiO₂ suspension by UV light. In concentrated aqueous suspension, crude oil was photodegraded on the surface of Na-bentonite and the photocatalyst TiO₂. Experiments have been carried out with Na-bentonite contaminated with crude oil mixed in a ratio of 1:1 with TiO₂ as well. The photooxidation processes were followed by total organic carbon content (TOC) and diffuse reflection infrared spectroscopy (DRIFT) measurements.     

Pt/H-TiO2催化剂制备及其甲醇电催化氧化性能

以四氯化钛为前驱体,采用水热法合成二氧化钛纳米棒（TiO₂,白色）,在纯H₂气氛,将其550 ^oC热处理2 h,即得有氧缺陷和Ti³⁺填隙原子的二氧化钛纳米棒（H-TiO₂,灰黑色）. 将Pt纳米粒子（~ 1.9 nm）负载于此两种二氧化钛纳米棒上,制得Pt/TiO₂和Pt/H-TiO₂催化剂. XRD和XPS测试表明,氢处理TiO₂晶型没有变化,仍属金红石型,但增加了Ti-OH表面物种. 电化学测试表明,H-TiO₂载体能够增强氧在Pt表面的吸脱附能力,从而提高其甲醇电催化氧化活性,Pt/H-TiO₂电极甲醇氧化峰电流密度为Pt/TiO₂电极的1.6倍、Pt/C电极的2.1倍.     

改性活性炭纤维可见光催化联合脱硫脱硝的研究

利用水合肼还原法制备的TiO₂/Cu₂O复合光催化剂对活性炭纤维(ACF)进行改性,利用SEM、XPS、BET以及XRD对其进行表征,研究改性后ACF的性质及其脱硫脱硝效果。研究表明,TiO₂/Cu₂O同时改性后的ACF表面孔径减小,但表面石墨碳和羰基(C=O)官能团增加,增强了ACF对NO和SO₂的吸附能力,从而提高了脱硫脱硝的效率,该催化剂在40℃、可见光的催化下脱硫效率达90%,脱硝效率达60%。