基于插层化学的单晶氧化钨纳米片的制备、表征与形成机制

结合插层化学与湿化学方法的优点, 建立了一种高比表面积、大径厚比、易分散的二维氧化钨(WO3)纳米片单晶的制备新方法. 微米级WO3与Bi2O3在800 ℃通过固相反应生成层状化合物Bi2W2O9; 所得到的Bi2W2O9经盐酸选择性溶出[Bi2O2]层后得到质子化形式的H2W2O7·xH2O相. 以H2W2O7·xH2O为钨源, 以辛胺插层所得无机-有机混杂纳米带为前驱物, 经硝酸氧化除去前驱物中的有机组分后得到正交相WO3·H2O纳米片; 将所得到的WO3·H2O纳米片在250~ 450 ℃和空气气氛中热处理2~5 h(升温速率为2 ℃/min), 得到单斜相WO3单晶纳米片. TEM与SEM分析结果表明, 单晶WO3·H2O与WO3纳米片的形貌相似, 其大小为(200~500) nm×(200~500) nm, 厚度为10~30 nm; 所得WO3·H2O与WO3纳米片单晶的厚度方向分别为[010]和[001]. N2吸附结果表明, WO3·H2O与WO3纳米片的比表面积分别可达到250与180 m2/g.     

Surface optical Raman modes in GaN nanoribbons

Raman scattering studies were performed in GaN nanoribbons grown along [1 0 0]. These samples were prepared inside Na‐4 mica nanochannels by the ion‐exchange technique and subsequent annealing in NH₃ ambient. Detailed morphological and structural studies including the crystalline orientation were performed by analyzing the vibrational properties in these GaN nanoribbons. Pressure in the embedded structure was calculated from the blue shift of the E₂(high) phonon mode of GaN. Possible red shift of optical phonon modes due to the quantum confinement is also discussed. In addition to the optical phonons allowed by symmetry, two additional Raman peaks were also observed at ∼633 and 678 cm⁻¹ for these nanoribbons. Calculations for the wavenumbers of the surface optical (SO) phonon modes in GaN in Na‐4 mica yielded values close to those of the new Raman modes. The SO phonon modes were calculated in the slab (applicable to belt‐like nanoribbon) mode, as the wavenumber and intensity of these modes depend on the size and the shape of the nanostructures. The effect of surface‐modulation‐assisted electron–SO phonon scattering is suggested to be responsible for the pronounced appearance of SO phonon modes. A scaling factor is also estimated for the interacting surface potential influencing the observed SO Raman scattering intensities. Copyright © 2010 John Wiley & Sons, Ltd.     

单根In掺杂ZnO纳米带场效应管的电学性质

采用化学气相沉积法合成了In掺杂ZnO纳米带,并对其进行了X射线衍射、光致发光及透射电镜表征.基于单根纳米带,采用廉价微栅模板法制备了背栅场效应管,利用半导体参数测试仪测量了场效应管的输出(Ids-Vds)和转移(Ids-Vgs)特性,得出相关电学参数,其中迁移率值为622 cm2·V-1·s-1,该值明显优于包括ZnO在内的大多数材料;讨论了迁移率提高的可能原因.     

Au-Ag/TiO_2-NB纳米纸催化剂的制备及其在CO低温催化氧化中的应用

采用连续两步光沉积法,在TiO2纳米带(TiO2-NB)表面沉积双金属Au-Ag纳米颗粒制得Au-Ag/TiO2-NB一维纳米结构,并将其组装成纳米纸多孔催化剂(Cat),其结构、形貌和性能经SEM,TEM,ICP,XRD,XPS和UV-Vis表征。以CO低温催化氧化为探针反应,考察了Ag/Au比(n)和还原预处理温度(T)对Cat催化活性的影响。结果表明:Cat0.8400表现出最佳的催化活性,CO转化率达94%。催化剂的失活是由反应初期极小尺寸的金属纳米颗粒团聚烧结和反应过程中中间产物碳酸盐的生成所致。     

高分子自组装Mn2O3花瓣状纳米带、纳米线的研究

通过控制热处理工艺条件, 利用Mn(CH3COO)2和具有特殊空间构型的聚乙烯醇(PVA), 在600 ℃合成了类花瓣状Mn2O3纳米带和纳米线结构. SEM, XRD表征分析证明Mn2O3纳米带结构为方铁锰矿晶型结构, 沿(222)方向择优生长. 分析了热处理工艺对一维纳米结构的影响机制. 初步探讨了Mn2O3一维纳米结构的生长机理.     

Raman spectroscopy of ZnS nanostructures

We report Raman scattering results of wurtzite ZnS nanowires, nanocombs, and nanobelts. The Raman spectrum obtained from ZnS nanowires exhibits first‐order phonon modes at 272, 284, and 350 cm⁻¹, corresponding to A₁/E₁ transverse optical, E₂ transverse optical, and A₁/E₁ longitudinal optical phonons, respectively. Several multiphonon modes are also observed. The longitudinal optical phonon mode varies in wavenumber for nanocombs and nanobelts, indicating that the residual strain varies during the morphological change from ZnS nanowires to nanocombs and ultimately to nanobelts. Interestingly, a surface optical (SO) phonon mode varies in wavenumber depending on the shape and surface roughness of the ZnS nanostructures. The surface modulation wavelengths of the ZnS nanowires, nanocombs, and nanobelts are estimated using the SO phonon dispersion relations and the observed SO phonon wavenumbers. Copyright © 2012 John Wiley & Sons, Ltd.     

表面修饰的钒氧化物纳米带上甲苯选择氧化反应

采用声化学水热法制备了V₂O₅纳米带,并将十六烷基膦酸负载在它和块状V₂O₅表面上,以修饰催化剂表面,通过调变催化剂中晶格氧活动性以及表面酸碱性来控制其催化甲苯氧化产物的选择性.结果表明,V₂O₅纳米带具有较强的晶格氧活动性,与普通块状V₂O₅相比,甲苯转化率更高,但苯甲醛和苯甲酸的总选择性下降.经过表面修饰后,V₂O₅纳米带的催化活性以及苯甲醛、苯甲酸总选择性增加;而块状V₂O₅上苯甲醛、苯甲酸总选择性更高,但催化活性显著下降.     

Template‐free synthesis of polyaniline nanobelts as a catalytic counter electrode in dye‐sensitized solar cells

Polyaniline (PAn) nanobelts were synthesized by simply mixing aniline and hydrochloric acid aqueous solution with ammonium peroxydisulfate and hydrochloric acid aqueous solution at room temperature without any templates. The PAn nanobelt paste with polytetrafluoroethylene as binder is proper for low‐cost and efficient casting processes such as doctor blade method, screen printing, spin‐casting, and even roll‐to‐roll painting. The porous network structure of the PAn nanobelt counter electrode was obtained after drying the paste on the conductive glass. The as‐prepared PAn nanobelt counter electrode showed nearly equivalent electrochemical catalytic activity as that of thermal decomposed Pt counter electrode, owing to the well‐connected conductive network and high active surface area. The power conversion efficiency of dye‐sensitized solar cell with PAn nanobelt counter electrode attained 90% of the value of the cell with Pt counter electrode. Copyright © 2014 John Wiley & Sons, Ltd.     

高分子自组装Mn2O3花瓣状纳米带、纳米线的研究

通过控制热处理工艺条件, 利用Mn(CH3COO)2和具有特殊空间构型的聚乙烯醇(PVA), 在600 ℃合成了类花瓣状Mn2O3纳米带和纳米线结构. SEM, XRD表征分析证明Mn2O3纳米带结构为方铁锰矿晶型结构, 沿(222)方向择优生长. 分析了热处理工艺对一维纳米结构的影响机制. 初步探讨了Mn2O3一维纳米结构的生长机理.     

PbS量子点/MoO3纳米带复合材料的低温气敏性能研究

采用液相法制备PbS量子点修饰MoO3纳米带复合材料.利用XRD、FESEM、TEM、EDS等表征手段分析样品组成、结构与形貌,分别将MoO3纳米带、PbS量子点、PbS量子点/MoO3纳米带组装成陶瓷管气敏元件并测试其对NH3的气敏性能.结果表明,在低温(20~100 ℃)下PbS量子点/MoO3纳米带复合材料对NH3具有良好检测能力,最低测试限为10 ppm.由于PbS量子点均匀分布在MoO3纳米带表面可形成异质结界面,这可有助于电子、空穴的分离,从而显著改善电子传输性能和气敏特性.