石墨烯-氧化钨复合薄膜的制备及界面电子传输特性

以偏钨酸铵为钨源、聚乙烯吡咯烷酮为连接剂,采用浸渍提拉法制备了石墨烯-氧化钨复合薄膜,利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)及Raman光谱等方法对复合结构材料进行了表征,并利用光电流测试、交流阻抗谱(EIS)、瞬态光电流谱和强度调制光电流谱等方法,研究复合薄膜电极在光电作用下界面上的载流子转移过程和电荷传输行为.结果表明,组成薄膜的氧化钨纳米颗粒与石墨烯充分复合,光电性能显著提高;与石墨烯复合后,薄膜的瞬态时间常数增大,电子-空穴对寿命延长;电子传输时间减少,为纯氧化钨薄膜的47.5%.     

脉冲激光沉积制备非晶La_(0.75)Sr_(0.25)MnO_3薄膜用于半透明阻变存储器（英文）

用脉冲激光沉积方法制备非晶La_(0.75)Sr_(0.25)MnO_3(a-LSMO)薄膜作为阻变器件(Ag/a-LSMO/ITO)的中间层,所得器件具有良好的非易失性和双极阻变行为。ITO衬底及超薄a-LSMO薄膜具有很高的可见光透过率,从而可制备半透明阻变器件。通过高分辨透射电镜直接观测到了在银电极与ITO电极间的银导电细丝。器件的阻变特性归因于在非晶镧锶锰氧层中的银导电细丝的生长与断裂。     

Ru(II)染料与聚3-甲基噻吩复合敏化纳米结构TiO_2电极的光电化学研究

利用光电流作用谱、循环伏安等光电化学方法研究了染料RuL2(SCN)2:2TBA(L=2,2'-bipydine-4,4'-dicarboxylicacid)与聚3-甲基噻吩(P3MT)复合敏化电极的光电化学性质.RuL2(SCN)2:2TBA/P3MT复合敏化TiO2纳米晶多孔膜电极比染料RuL2(SCN)2:2TBA敏化TiO2纳米结构电极的光电转换效率大幅度提高.复合敏化电极中存在p-n异质结有效地抑制了电子的反向复合,减少了电子的损失.     

石墨烯-氧化钨复合薄膜的制备及界面电子传输特性

以偏钨酸铵为钨源、聚乙烯吡咯烷酮为连接剂,采用浸渍提拉法制备了石墨烯-氧化钨复合薄膜,利用X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）及Raman光谱等方法对复合结构材料进行了表征,并利用光电流测试、交流阻抗谱（EIS）、瞬态光电流谱和强度调制光电流谱等方法,研究复合薄膜电极在光电作用下界面上的载流子转移过程和电荷传输行为. 结果表明,组成薄膜的氧化钨纳米颗粒与石墨烯充分复合,光电性能显著提高;与石墨烯复合后,薄膜的瞬态时间常数增大,电子-空穴对寿命延长;电子传输时间减少,为纯氧化钨薄膜的47.5%.     

脉冲激光沉积制备非晶La0.75Sr0.25MnO3薄膜用于半透明阻变存储器

用脉冲激光沉积方法制备非晶La_0.75Sr_0.25MnO₃（a-LSMO）薄膜作为阻变器件（Ag/a-LSMO/ITO）的中间层,所得器件具有良好的非易失性和双极阻变行为。ITO衬底及超薄a-LSMO薄膜具有很高的可见光透过率,从而可制备半透明阻变器件。通过高分辨透射电镜直接观测到了在银电极与ITO电极间的银导电细丝。器件的阻变特性归因于在非晶镧锶锰氧层中的银导电细丝的生长与断裂。     

表面修饰的TiO_2太阳能电池界面特性研究

用水热法制备了具有典型锐钛矿晶型的TiO2纳米材料,采用Cr(NO3)3对TiO2薄膜电极进行修饰改性。用X射线衍射(XRD)、扫描电子显微镜(SEM)和光电子能谱(XPS)测试电极的物相及表面结构,结果显示TiO2薄膜表面包覆一层粒径较大的氧化铬颗粒,整个电极仍保持均匀的多孔结构。电流-电压(I-V)曲线测试结果显示,改性后最佳电极的短路电流和光电转换效率分别比改性前提高了31.1%和40.4%。用电化学阻抗谱(EIS)测试电池的界面特性,从测试结果可以看出,相同偏压下,改性后电池的TiO2/染料/电解质界面电阻更大,说明氧化铬包覆层在一定程度上抑制了界面的电子复合,改善了电池的光电输出特性。     

TiO2包覆不同微结构纳米碳纤维薄膜电极的光电化学性能

采用溶胶-凝胶法制备了TiO2包覆不同微结构的纳米碳纤维(Carbon nanofibers, CNF), 包括板式纳米碳纤维(Platelet-CNF, PCNF)和鱼骨式纳米碳纤维(Fish-bone-CNF, FCNF)的复合薄膜电极. 用光电流作用谱和光电流-电势图等方法研究了复合薄膜电极的光电化学性能. 研究结果表明, 复合薄膜电极表现出n型半导体特征, 薄膜中CNF的存在有助于光生电子和空穴有效地分离, 提高了光电转换效率, TiO2包覆PCNF薄膜电极在可见光范围内存在明显的光电响应.     

脉冲激光沉积制备非晶La0.75Sr0.25MnO3薄膜用于半透明阻变存储器

用脉冲激光沉积方法制备非晶La_0.75Sr_0.25MnO₃（a-LSMO）薄膜作为阻变器件（Ag/a-LSMO/ITO）的中间层,所得器件具有良好的非易失性和双极阻变行为。ITO衬底及超薄a-LSMO薄膜具有很高的可见光透过率,从而可制备半透明阻变器件。通过高分辨透射电镜直接观测到了在银电极与ITO电极间的银导电细丝。器件的阻变特性归因于在非晶镧锶锰氧层中的银导电细丝的生长与断裂。     

紫外臭氧处理增强溶液法MoO_3薄膜的空穴注入能力（英文）

空穴注入层对有机发光二极管的性能有重要的影响,尤其是当器件中的空穴传输材料的最高占据分子轨道能级较深的时候。近年来有许多关于新型的溶液法空穴注入材料的研究。在本文中,我们对溶液法MoO_3薄膜使用了三种不同的处理方法来研究其对空穴注入性能的影响,即:在空气中150°C退火;在空气中150°C退火再紫外臭氧处理(UVO) 15 min;只进行UVO处理15 min。结果发现当MoO_3薄膜在空气中150°C退火后,器件的电流最小,空穴注入能力最差。而当MoO_3薄膜经过UVO处理后,器件的电流显著增大,工作电压大幅下降,器件性能接近于蒸镀的MoO_3薄膜的器件。更惊喜的是,这种改善在MoO_3薄膜仅作UVO处理后也可获得。经定量计算发现MoO_3薄膜经过UVO处理后的空穴注入效率能提高到约0.1。XPS分析表明通过UVO处理后,MoO_3薄膜中Mo~(5+)成分减少并且薄膜表面的富氧吸附物被有效地消除,使得其化学计量基本与蒸镀的MoO_3薄膜相同。基于这种经UVO处理的溶液法MoO_3作为空穴注入层,器件的最大电流效率可达到48.3 cd·A~(-1)。     

宽带隙Cu(In,Al)Se2薄膜的制备及表征

以特殊脉冲电沉积方法制备CuInSe2(CIS)前驱体薄膜, 通过真空蒸镀法在CIS薄膜上沉积Al膜, 经硒化退火后在氧化铟锡(ITO)基底上制备了Cu(InAl)Se2(CIAS)薄膜. 采用扫描电子显微镜(SEM)、X射线能谱(EDS)、X射线衍射(XRD)、X射线光电子能谱(XPS)、紫外-可见吸收光谱(UV-Vis)对其形貌、结构、成分及光学吸收性质进行了表征. 结果表明, 制备的CIAS薄膜颗粒均匀, 表面平整致密, 呈黄铜矿结构. 薄膜在可见光区具有良好的吸收, 带隙约为1.65 eV.     

Liquid — Liquid extraction of silver(I) by diphenyl-2-pyridylmethane in benzene from aqueous mineral acid — Thiocyanate solutions

Liquid — liquid extraction of Ag(I) by diphenyl-2-pyridylmethane (DPPM) in benzene from aqueous nitric and sulfuric acid solutions containing thiocyanate ions has been studied at ambient temperature (24±2 °C). The metal is extracted quantitatively from 0.01M HNO₃+0.02M KSCN; or 0.25M H₂SO₄+0.02M KSCN by 0.1M DPPM (optimum extraction conditions). Slope analysis indicates that two types of ion-pair complexes i.e. [(DPPMH)⁺·Ag(SCN) ₂ ^– ] and [(DPPMH) ₂ ⁺ ·Ag(SCN) ₃ ^2– ] are involved in the extraction process. Separation factors determined at optimum conditions reveal the separation of Ag(I) from Cs(I), Br(I), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Fe(III), Au(III) (from HNO₃ solution only), Cr(III), Hf(IV), Ta(V), Sn(IV) and Cr(VI). With the exception of thiosulfate, other complexing anions like ascorbate, acetate, citrate, oxalate do not hinder the extraction of Ag(I) under optimum conditions.     

Electrochemical solid-state phase transformations of silver nanoparticles

Adenosine triphosphate (ATP)-capped silver nanoparticles (ATP-Ag NPs) were synthesized by reduction of AgNO(3) with borohydride in water with ATP as a capping ligand. The NPs obtained were characterized using transmission electron microscopy (TEM), UV-vis absorption spectroscopy, X-ray diffraction, and energy-dispersive X-ray analysis. A typical preparation produced ATP-Ag NPs with diameters of 4.5 ± 1.1 nm containing ~2800 Ag atoms and capped with 250 ATP capping ligands. The negatively charged ATP caps allow NP incorporation into layer-by-layer (LbL) films with poly(diallyldimethylammonium) chloride at thiol-modified Au electrode surfaces. Cyclic voltammetry in a single-layer LbL film of NPs showed a chemically reversible oxidation of Ag NPs to silver halide NPs in aqueous halide solutions and to Ag(2)O NPs in aqueous hydroxide solutions. TEM confirmed that this takes place via a redox-driven solid-state phase transformation. The charge for these nontopotactic phase transformations corresponded to a one-electron redox process per Ag atom in the NP, indicating complete oxidation and reduction of all Ag atoms in each NP during the electrochemical phase transformation.     

ZnO/Ag复合膜的制备及其润湿性转换研究

利用溶胶-凝胶技术制备了ZnO/Ag复合膜. 采用X射线粉末衍射和扫描电子显微镜对其物相组成、 晶型结构以及表面形貌进行了表征, 采用接触角测试仪对其润湿性进行了表征, 并研究了紫外光照射下Ag的掺杂量对ZnO薄膜润湿性的影响. 结果表明, 当Ag掺杂量(摩尔分数)为5%时, 所得膜的润湿性转换速率最快, 紫外光照3 h后, 其润湿性由超疏水性转换为亲水性, 黑暗中放置5 d后, 亲水性再次转换为超疏水, 实现了润湿性的可逆转换.     

Preparation and Characterization of Ag2 O/Organicsilicone Self-assemblied Composite Film

The composite film of nanometer AgO2/silane coupling reagent aminopropyltriethoxy-silane (CH3O)3Si(CH2)3NH2was prepared on single-crystal silicon by the self-assembly of silane on the hydroxylated substrate followed with the deposition of nanometer AgO2 on the silane SAMs from an aqueous Ag2O gel. The resultant composite film was characterized by means of X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The contact angles of distilled water on the silane SAMs and the composite film were measured to compare the surface states. The experiment shows that the nanometer Ag2O can be easily incorporated in the silane SAMs and lead to changed surface state of the composite film. Nanometer Ag2O crystallites in a size of about 20 nm distribute quite uniformly in the composite film. It was anticipated that the composite film might find application to the protection of single-crystal Si substrate in MEMS devices and also propose a novel single electron device structure based on nanoscale Ag2O colloidal particles.     

First structural example of a metal uncoordinated mesoionic imidazo[1,5-a]pyridine and its precursor intermediate copper complex: an insight to the catalytic cycle

Four copper complexes of a tridentate Schiff base ligand, 2-pyridyl-N-(2'-methylthiophenyl) methyleneimine, L(1) have been synthesized. All theses species, namely, [L(1)Cu(2)(SCN)(3)](n) (1), [Cu(SCN)(CH(3)CN)](n) (3), [(L(1))Cu(N(3))(Cl)] (4) and [(L(1))Cu(N(3))(SCN)] (5) have been structurally characterized. Complex 1 in acetonitrile promotes cycloaddition of a Cu(II) bound SCN(-) ion to L(1) that exclusively and stoichiometrically forms a mesoionic imidazo[1,5-a]pyridine, namely, 3-(imino-N'-2-methylthiophenyl)imidazo[1,5-a]pyridinium-1-thiolate (2) and a thiocyanato bridged Cu(i) complex, [Cu(SCN)(CH(3)CN)](n) (3). The X-ray crystal structure of 1 confirms the presence of square-pyramidal Cu(II) and tetrahedral Cu(I) ions in N(3)S(2) and N(2)S(2) coordination environments, respectively, bridged to each other via thiocyanate anion. The Cu(II) ions are bonded to a tridentate ligand L(1) and two SCN(-) ions occupy the remaining equatorial and an axial coordination site to adopt a square-pyramidal coordination geometry. To investigate which SCN(-) ion, axially or equatorially bound to Cu(II) center, underwent cycloaddition to L(1) to form 2, two mononuclear Cu(II) complexes 4 and 5 have been synthesized and their reactivity towards externally added KSCN was studied. The molecular structures of 4 and 5 feature a meridionally bound L(1) and an azide ion (N(3)(-)) in the square plane, while a Cl(-) or SCN(-) ion are occupying the axial site, respectively, to fulfill square-pyramidal coordination geometry. Complex 4 reacts with SCN(-) ion to form 5. That an MeCN solution of 5 itself, or of 5 in the presence of KSCN, does not produce 2, supports that possibly the Cu(II) bound equatorial SCN(-) ion is responsible for cycloaddition to L(1). Dark purple solid 2 has also been prepared (turnover number ~4 or 41% yield) efficiently following an alternative and easier one-pot synthesis procedure, that is from a mixture of KSCN and L(1) in the presence of a catalytic amount of anhydrous CuCl(2) (10 mol%) in MeCN in air. The X-ray crystal structure, (1)H NMR spectrum and solution conductivity measurements strongly support that 2 is mesoionic. An MeCN solution of 2 fluoresces at room temperature upon excitation at 240 nm with an emission maximum λ(em) at 470 nm, associated with a quantum yield of 0.16 with respect to a standard Rhodamine-6G fluorophore.     

Electrodeposition of manganese and molybdenum mixed oxide thin films and their charge storage properties

Manganese and molybdenum mixed oxides in a thin film form were deposited anodically on a platinum substrate by cycling the electrode potential between 0 and +1.0 V vs Ag/AgCl in aqueous manganese(II) solutions containing molybdate anion (MoO(4)2-). A possible mechanism for the film formation is as follows. First, electrooxidation of Mn2+ ions with H2O yields Mn oxide and protons. Then, the protons being accumulated near the electrode surface react with MoO(4)2- to form polyoxomolybdate through a dehydrated condensation reaction (by protonation and dehydration). The condensed product coprecipitates with the Mn oxide. Cyclic voltammetry of the Mn/Mo oxide film-coated electrode in aqueous 0.5 M Na2SO4 solution exhibited a pseudocapacitive behavior with higher capacitance and better rate capability than that of the pure Mn oxide prepared similarly, most likely as a result of an increase in electrical conductivity of the film. Electrochemical quartz crystal microbalance and X-ray photoelectron spectroscopy clearly demonstrated that the observed pseudocapacitive behavior results from reversible extraction/insertion of hydrated protons to balance the charge upon oxidation/reduction of Mn3+/Mn4+ in the film.     

Über die Trithiocyanatoargentate Rb2Ag(SCN)3 und Cs2Ag(SCN)3

On the Trithiocyanatoargentates Rb₂Ag(SCN)₃ and Cs₂Ag(SCN)₃ The trithiocyanatoargentates Rb₂Ag(SCN)₃ and CsAg(SCN)₃ are obtained by crystallization from highly concentrated aqueous solutions. In the crystal structures the Ag atoms are surrounded tetrahedrally by the S atoms of 4 SCN groups. These Ag(SCN)₄ tetrahedra are connected by common corners to polymer \documentclass{article}\pagestyle{empty}\begin{document}$ {}_\infty ^1 \left[{{\rm Ag}\left({{\rm SCN}} \right)_2 \left({{\rm SCN}_{2/2}} \right)} \right] $\end{document}¹[Ag(SCN)₂(SCN)_2/2] anion in Rb₂Ag(SCN)₃, whereas dimeric Ag₂(SCN)₆ anions were found in the Cs compound.     

Synthesis and Crystal Structure of Me3NHCu2(SCN)3, Me2C=NMe2Cu2(SCN)3, and Me2C=NMe2Ag2(SCN)3. Three‐dimensional Networks of Thiocyanatometallates(I)

Attempts to build up polyanionic networks on the basis of thiocyanatometallates of Cu^I and Ag^I led to the synthesis of three new tris(thiocyanato)dimetallates(I) A[M₂(SCN)₃] with M = Cu, Ag and A = Me₃NH and A = [Me₂CNMe₂]. The crystal structures show distorted tetrahedral [M(SCN)₃(NCS)] and [M(SCN)₂(NCS)₂] building groups interlinked by SCN bridges. The resulting 3‐dimensional frame works accommodate the counter cations in spacious voids. Me₃NHCu₂(SCN)₃ ( 1 ) was synthesized by reaction of CuSCN with (CH₃)₃NHCl in the presence of an excess of KSCN in acetone. 1 crystallizes in the monoclinic space group P2₁/c with a = 578.4(1), b = 3025.1(5), c = 754.7(3) pm; β = 112.53°; Z = 4. The reaction of CuSCN or AgSCN with (CH₃)₂NH₂Cl and KSCN in acetone resulted in the formation of [Me₂CNMe₂]Cu₂(SCN)₃ ( 2 ) and [Me₂CNMe₂]Ag₂(SCN)₃ ( 3 ). Compound 2 crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 720.6(1), b = 1161.5(1), c = 1655.0(2) pm; Z = 4. The isotypical structure of 3 exhibits somewhat larger unit cell dimensions; a = 743.4(1), b = 1222.5(1), c = 1683.9(2) pm.     

硫氰根选择性吸附在g-C_3N_4/Ag表面增强其光催化制氢性能(英文)

作为一种无金属的新型半导体材料,g-C_3N_4因具有稳定的物理化学性质及合适的能带结构而引起人们的关注.理论上g-C_3N_4完全满足水分解的电势条件.然而研究发现,g-C_3N_4材料本身的光催化性能并不好,这主要是由于半导体材料被光激发后生成的自由电子和空穴还没来得及到达材料表面参与反应,就在材料体相内发生复合,导致电子参与有效光催化制氢反应的几率大大降低.同时还发现,将少量的贵金属,如Pt,Au,Pd作助催化剂修饰在该半导体表面,其光催化性能明显提高.但由于这些贵金属储量非常稀少,价格昂贵,导致它们的使用受到一定限制.而Ag作为一种价格远低于Pt,Au,Pd的贵金属,也得到了广泛的研究.研究表明,金属Ag储存电子的能力很好,因此可以有效地将半导体上生成的光生电子快速转移到Ag上面去,从而达到电子空穴快速分离的目的.但是在光催化制氢过程中,Ag吸附H~+的能力较弱,致使电子与H~+反应的诱导力较弱,使得Ag释放电子的能力较差.因此可以通过提高Ag表面对H~+的吸附强度,以加速Ag的电子释放,通过表面修饰来提高Ag助剂的光催化活性.研究发现,Ag纳米粒子表面与含硫化合物之间存在很强的亲和力.硫氰根离子(SCN~–)具有很强的电负性,容易吸附溶液中H~+离子,并且也易吸附在Ag纳米粒子的表面.因此可以利用Ag与SCN~–的作用来增强Ag释放电子的能力.本文采用光还原法将Ag沉积在g-C_3N_4半导体材料表面,然后通过在制氢牺牲剂中加入KSCN溶液,利用SCN~-与Ag的亲和力来提高光生电子参与光催化反应的效率.结果表明,在SCN~-存在的情况下,g-C_3N_4/Ag的光催化制氢性能显著提高.当制氢溶液中SCN~–浓度为0.3 mmol L~(–1)时,材料的光催化制氢性能达最大,为3.89μmol h~(–1),比g-C_3N_4/Ag性能提高5.5倍.基于少量的SCN~–就能明显提高g-C_3N_4/Ag材料的光催化性能,我们提出了一个可能性的作用机理:金属银和SCN~-协同作用,即银纳米粒子作为光生电子的捕获和传输的一种有效的电子传递介质,而选择性吸附在银表面的SCN~-作为界面活性位点有效地吸附溶液中的质子以促进产氢反应,二者协同作用,加速了g-C_3N_4-Ag–SCN~-三物种界面之间电荷的传输、分离及界面催化反应速率,有效抑制了g-C_3N_4主体材料光生电子和空穴的复合,因而g-C_3N_4/Ag–SCN复合材料的光催化制氢性能提高.考虑到其成本低、效率高,SCN~–助催化剂有很大的潜力广泛应用于制备高性能的银修饰光催化材料.     

Self-assembled monolayers of aromatic selenolates on noble metal substrates

Self-assembled monolayers (SAMs) formed from bis(biphenyl-4-yl) diselenide (BBPDSe) on Au(111) and Ag(111) substrates have been characterized by high-resolution X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, infrared reflection absorption spectroscopy, water contact angle measurements, and scanning tunneling microscopy (STM). BBPDSe was found to form contamination-free, densely packed, and well-ordered biphenyl selenolate (BPSe) SAMs on both Au and Ag. Spectroscopic data suggest very similar packing density, orientational order, and molecular inclination in BPSe/Au and BPSe/Ag. STM data give a similar intermolecular spacing of 5.3 +/- 0.4 A on both Au and Ag but exhibit differences in the exact arrangement of the BPSe molecules on these two substrates, with the (2 square root[3] x square root[3])R30 degrees and (square root[3] x square root[3])R30 degrees unit cells on Au and Ag, respectively. There is strong evidence for adsorbate-mediated substrate restructuring in the case of Au, whereas no clear statement on this issue can be made in the case of Ag. The film quality of the BPSe SAMs is superior to their thiol analogues, which is presumably related to a better ability of the selenolates to adjust the surface lattice of the substrate to the most favorable 2D arrangement of the adsorbate molecules. This suggests that aromatic selenolates represent an attractive alternative to the respective thiols.