真空烧结下TinO2n-1多孔电极的制备及性能

为给工业制备TinO2n-1多孔电极提供技术支持,以TiH2与TiO2为合成原料,采用高温烧结-压片法制备了TinO2n-1电极。通过扫描电镜(SEM)、X射线衍射仪(XRD)进行材料表征,探究了制备TinO2n-1电极的工艺合理性,利用电化学工作站考察了自制TinO2n-1电极的性能。结果表明:TiH2与TiO2的摩尔比为1∶5,真空下烧结温度为950℃时,可得到主相为Ti4O7的TinO2n-1电极。将自制的亚氧化钛电极与石墨电极分别进行阳极极化测试,亚氧化钛电极析氧电位维持在2.25 V,远高于石墨电极的1.60 V,在循环伏安测试中,TinO2n-1电极表现出很高的电化学稳定性。

Magnéli phases TinO2n-1 as novel ozonation catalysts for effective mineralization of phenol

Magnéli phases Ti_nO_(2n-1)have been demonstrated as promising environmentally friendly materials in advanced oxidation processes.In this study,Magnéli phases Ti_nO_(2n-1)have been used as catalysts for the ozonation of phenol in aqueous solution for the first time.The materials exhibited excellent catalytic ozonation activities both in phenol degradation and mineralization.When Ti_4O_7was added,the reaction rate was six-fold higher than that of with ozone alone,while the total organic carbon removal rate was substantially elevated from around 19.2%to 92%.By virtue of the good chemical stability of the materials,a low metal leaching of less than 0.15 mg·L^(-1)could effectively avoid the secondary pollution by metal ions.Radical quenching tests revealed·O_2^-and^1O_2to be active oxygen species for phenol degradation at p H 5.As semiconductor catalysts,Ti_nO_(2n-1)materials show electronic transfer capability.Ozone adsorbed at B-acid sites of the catalyst surface can capture an electron from the conversion of Ti(III)to Ti(IV),and is thereby broken into the active oxygen species.It was interesting to observe that Ti_nO_(2n-1)exhibit better catalytic activity for phenol degradation and mineralization with lower n value.The difference in electrical conductivity can be considered as a major factor for the catalytic performances.More highly conductive catalysts show a faster electron-transfer rate and better catalytic activity.Thus,significant evidences have been obtained for a single-electron-transfer mechanism of catalytic ozonation with Magnéli phases Ti_nO_(2n-1).

Ti_nO_(2n-1)电极电催化氧化有机污水中二甲基苯酚的探究

从Ti_nO_(2n-1)电极的制备入手,以Ti H2与Ti O2为合成原料,采用高温压片-真空烧结法制得Ti_nO_(2n-1)多孔电极。通过SEM、XRD技术对电极进行了表征,随后利用电化学测试方法考察了Ti_nO_(2n-1)电极的性能,并设计了有机污染物处理试验考察了电极的电催化氧化效能。结果显示:自制得到了主相为Ti4O7的Ti_nO_(2n-1)多孔电极,将自制的Ti_nO_(2n-1)多孔电极与石墨电极分别进行电化学测试,Ti_nO_(2n-1)电极的析氧电位保持在2.25 V左右,石墨电极仅为1.60 V、电化学稳定性等指标均优于石墨电极。在二甲基苯酚(DPM)模拟污水的电催化氧化过程中,Ti_nO_(2n-1)电极在105 min内对DPM的消解率达到93.1%,对COD的去除率达到84%,反应过程符合一级动力学过程。

Magneli phase titanium sub-oxide conductive ceramic Ti_nO_(2n-1) as support for electrocatalyst toward oxygen reduction reaction with high activity and stability

Magneli phase titanium sub-oxide conductive ceramic Tin O2n-1 was used as the support for Pt due to its excellent resistance to electrochemical oxidation, and Pt/Tin O2n-1 composites were prepared by the impregnation-reduction method. The electrochemical stability of Tin O2n-1 was investigated and the results show almost no change in the redox region after oxidation for 20 h at 1.2 V(vs NHE) in 0.5 mol/L H2SO4 aqueous solution. The catalytic activity and stability of the Pt/Tin O2n-1 toward the oxygen reduction reaction(ORR) in 0.5 mol/L H2SO4 solution were investigated through the accelerated aging tests(AAT), and the morphology of the catalysts before and after the AAT was observed by transmission electron microscopy. At the potential of 0.55 V(vs SCE), the specific kinetic current density of the ORR on the Pt/Tin O2n-1 is about 1.5 times that of the Pt/C. The LSV curves for the Pt/C shift negatively obviously with the half-wave potential shifting about 0.02 V after 8000 cycles AAT, while no obvious change takes place for the LSV curves for the Pt/Tin O2n-1. The Pt particles supported on the carbon aggregate obviously, while the morphology of the Pt supported on Tin O2n-1 remains almost unchanged, which contributes to the electrochemical surface area loss of Pt/C being about 2times that of the Pt/Tin O2n-1. The superior catalytic stability of Pt/Tin O2n-1 toward the ORR could be attributed to the excellent stability of the Tin O2n-1 and the electronic interaction between the metals and the support.

微波加热Mg-TiO2混合物的研究

在氩气气氛下微波辐射加热Mg-TiO2混合物,通过XRD、SEM研究了不同n(Mg)/n(TiO2)和反应温度对产物物相、形貌的影响。n(Mg)/n(TiO2)影响产物中Mg-TiO2化合物的种类和亚氧化钛的生成,对产物的形貌没有明显影响。反应温度影响产物的物相比例,温度升高会导致产物的颗粒烧结粗大。使用微波加热Mg-TiO2虽然生成了钛酸镁及亚氧化钛,但生成量少、分离困难,因此该制备方法不可取。

Ti_nO_(2n-1)系列氧化物的特性、制备方法及应用

TinO2n-1是钛的一系列亚化学计量氧化物,具有导电性好、可见光响应能力强、电化学性能优异、环保无毒等诸多优良特性。其中,Ti4O7单晶的电导率达1500 S·cm-1,和石墨相当。TinO2n-1的相结构、电磁学以及电化学方面的研究已有很多进展。目前,科研人员已开发出了一系列制备TinO2n-1的方法,最主要的方法是高温还原Ti O2及其前驱体,已成功制备出纳米球、纳米管及纳米线等不同形貌的材料。由于其特性优良,TinO2n-1在惰性电极、催化剂载体、锂电池、热电及光电材料、光催化降解等方面的应用引起了研究人员的关注,并得到一些商业化应用,例如Ti4O7已开发为商业电极等,具有广阔的应用前景。本文对TinO2n-1的结构及物化特性进行了总结,并概括归纳了该系列亚氧化物的制备方法,最后介绍了TinO2n-1目前的应用情况并对今后的发展作出展望,以期为TinO2n-1系列化合物的研究发展提供相关的参考和依据。

铝热还原TiO2制备Magnéli相低价钛氧化物工艺及过程机制研究

Magnéli相（TinO2n-1）（4〈n〈10）低价钛氧化物材料具有导电性好、可见光响应强、耐磨、优异的耐腐蚀性能等,被广泛应用于制备电池、惰性电极及光催化降解材料。在空气气氛下利用铝还原锐钛矿相TiO2制备Magnéli相低价钛氧化物材料,研究了不同焙烧温度、焙烧时间和配铝量等工艺参数对制备黑色Magnéli相低价钛氧化物复合材料相变过程的影响,并采用X射线衍射（XRD）、拉曼光谱（Raman）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）等分析手段对制备出的Magnéli相低价氧化物复合材料的物相组成变化及微观组织形貌进行表征,结果表明：不同焙烧温度和焙烧时间下制备的样品主要物相为Ti9O17,Ti8O15,Ti7O13,Ti4O7,随着焙烧温度的升高和焙烧时间的延长,还原程度不断加深,TinO2n-1中的n值不断降低。制备的Magnéli相低价氧化物材料呈颗粒状,粒径200～400 nm左右。通过稀盐酸浸出,可以将Magnéli相材料中过剩的铝除去得到较为纯净的Magnéli相TinO2n-1材料。