纯相Li_2MnO_3薄膜的制备及作为锂离子电池正极材料的电化学行为

采用固相烧结法制备了纯相Li2MnO3正极材料及靶材,采用脉冲激光沉积(PLD)法在氧气气氛、不同温度下沉积了Li2MnO3薄膜.通过X射线衍射(XRD)和拉曼(Raman)光谱表征了薄膜的晶体结构,采用扫描电镜(SEM)观察薄膜形貌及厚度,利用电化学手段测试了Li2MnO3薄膜作为锂离子电池正极材料性能.结果表明,PLD方法制备的纯相Li2MnO3薄膜随着沉积温度升高薄膜结晶性变好.25℃沉积的薄膜难以可逆充放电,400℃沉积的薄膜具有较高的电化学活性和循环稳定性.相对于粉末材料,400与600℃制备的Li2MnO3薄膜电极平均放电电位随着循环次数的衰减速率明显低于相应的粉体材料.     

La2CuO4阴极薄膜的相转变及其对电化学性能的影响

通过调控薄膜的沉积条件,探索La₂CuO₄的晶体结构对电化学性质的影响。采用脉冲激光沉积设备在YSZ(100)单晶基底上沉积一系列La₂CuO₄薄膜,通过调节沉积时的氧压,制备了不同晶体结构的La₂CuO₄薄膜。 研究表明,沉积氧压的变化使薄膜晶体结构发生相转变,从T'相→T^*相→T相。 T'相为沿着c轴择优生长的单晶四方相,且表现出较大的界面极化电阻,在850 ℃的R_p值为2.351 Ω·cm²。 T^*相为T'相和T相的混合相,在850 ℃的电阻值介于T'相和T相之间。 T相为正交相,相对于其它相结构表现出较低的界面极化电阻,沉积氧压为26.60 Pa下制备的T相在850 ℃的电阻值为0.783 Ω·cm²,比T'相的电阻值低近67%。 并且,正交相表面有相对较高的氧空位浓度,有利于氧气的吸附和扩散,加速了阴极的氧还原反应。 因此,具有正交对称性的La₂CuO₄的电化学性质优于其它对称性。 这一结果也表明可以通过改变薄膜材料的晶体结构,降低界面极化电阻,提高阴极薄膜的电化学性能。     

两步互扩散法制备高性能CsPbCl3薄膜紫外光电探测器

紫外光电探测器无论在军用和民用上都有着巨大的应用前景,CsPbCl₃作为钙钛矿家族中形成能最大,化学性能稳定的成员,在可见光盲区的紫外光电探测器中有着很大潜在的应用价值。本文针对CsPbCl₃薄膜难以制备的问题,发展了一种两步互扩散溶液法,通过控制前驱体PbCl2的形貌,成功地制备了CsPbCl₃薄膜。利用扫描电镜、吸收光谱和X射线表征技术,证实了制备出的薄膜表面平整无孔洞、晶粒饱满和吸光度强。通过瞬态荧光和变激发光强的稳态荧光,揭示了薄膜具有载流子寿命长、缺陷态少等优异性能。最终构建出了响应度为0.75 A·W^?1的横向结构紫外光电探测器,为将来进一步发展高性能CsPbCl₃薄膜紫外光电探测器奠定了基础。     

Ti表面修饰纳米TiO2膜电极的电催化活性

用电化学合成法在Ti表面修饰一层纳米TiO₂膜,TEM和XRD测试表明晶型为锐钛矿型,晶粒平均尺寸为25nm.用循环伏安法、循环方波伏安法和电解合成法研究了纳米TiO₂膜电极在硫酸介质中的氧化还原行为以及对硝基苯还原的电催化活性。结果表明,纳米TiO₂膜电极具有异相氧化还原催化行为,膜中的Ti(Ⅳ)/Ti(Ⅲ)作为媒质间接电还原硝基苯为对氨基苯酚,收率和电流效率分别达91.6%和95.2%.     

铌酸银可见光催化降解聚氯乙烯薄膜

采用涂层法在玻璃基底上分别制备了纯聚氯乙烯(PVC)薄膜和添加水热法制备的钙钛矿型铌酸银(AgNbO₃)光催化剂的复合薄膜(PVC-wAgNbO₃, 其中w为AgNbO₃的质量分数), 在500 W氙灯照射120 min条件下进行了薄膜的光催化降解实验. 利用X射线衍射仪(XRD)、 扫描电子显微镜(SEM)和傅里叶变换红外光谱仪(FTIR)等对光照前后薄膜的形貌及光催化降解过程进行了表征. 结果表明, 在光催化降解过程中纯PVC薄膜失重率为4.09%, 而PVC-3%AgNbO₃, PVC-6%AgNbO₃, PVC-9%AgNbO₃和PVC-15%AgNbO₃复合薄膜分别失重20.36%, 23.52%, 27.62%和33.83%. AgNbO₃光催化剂加速了PVC薄膜的降解, 且随着AgNbO₃光催化剂添加量的增加, PVC薄膜的光催化降解速率不断增大.     

Sn4+掺杂对TiO2纳米颗粒膜光催化降解苯酚活性的影响

金属离子掺杂能改善TiO2纳米微粒光催化活性,在光降解大气和水污染物的研究中,已引起人们的重视[1,2].实验证明,掺杂物的浓度、掺杂离子的分布、掺杂能级与TiO2能带匹配程度、掺杂离子d电子的组态、电荷的转移和复合等因素对催化剂的光催化活性有直接影响[3].Kamat等[4]曾利用TiO2颗粒与SnO2颗粒混合制膜,使光催化剂活性得到提高.但Sn4+掺杂TiO2用于光催化剂尚少见报道.本文采用等离子体化学气相沉积法(PECVD)[5]制备了Sn4+离子掺杂的TiO2纳米颗粒膜催化剂(TiO2-Sn),考察了其对苯酚的光催化降解活性,讨论了Sn4+离子的掺杂方式及光催化活性提高的机理.     

化学溶液沉积法制备自取向BiFeO3多铁薄膜

通过化学溶液沉积法在氧化铟锡(ITO)/导电玻璃上生长了BiFeO₃多晶薄膜.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱分析仪(XPS)、磁性测量系统(MPMS)和铁电测试仪对样品的结构、形貌、元素价态、铁磁性和铁电性进行研究.结果表明, 薄膜为自取向生长, 具有良好的[101] 生长取向和平整的表面.室温下, 样品呈铁磁性, 沿样品取向方向为易磁化轴方向.铁电测试结果表明, 其饱和电极化强度达到51.3 μC/cm².     

Ru(bpy)2(NCS)2染料敏化CdS/Zn2+TiO2复合半导体纳米多孔膜的光电化学

采用水热法合成了Zn²⁺离子掺杂的TiO₂纳米粒子[Zn²⁺掺杂量0.5%(物质的量的比)],并用光电化学方法研究了经Ru(bpy)₂(NCS)₂(bpy=2,2′bipyridine₄,4′dicarboxylicacid)分别敏化的掺杂Zn²⁺的TiO₂电极(简写为Zn²⁺-TiO₂)和CdS/Zn²⁺-TiO₂复合半导体纳米多孔膜电极的光电化学行为.实验证明Ru(bpy)₂(NCS)₂敏化CdS/Zn²⁺-TiO₂复合半导体纳米多孔膜电极比单独敏化Zn²⁺-TiO₂电极的光电转换效率高,且敏化Zn²⁺TiO₂电极和敏化CdS/Zn²⁺TiO₂复合半导体纳米多孔膜电极比Zn²⁺-TiO₂电极的光电流产生的起始波长都向长波方向移动.在360600nm范围内,Ru(bpy)₂(NCS)₂敏化CdS/Zn²⁺-TiO₂复合半导体纳米多孔膜电极光电转换效率最好.     

溶解氧及波长对光助阳极沉积CeO2薄膜的影响

本文主要研究在含有0.05 mol·L^-1硝酸铈、0.1 mol·L^-1乙酸铵和70%（体积比）乙醇的镀液中通过阳极电沉积法在316 L不锈钢电极表面上制备CeO₂薄膜,并讨论了三种单色光波长以及镀液中溶解氧对阳极沉积CeO₂的影响. 采用计时安培曲线、椭圆偏振光谱、扫描电子显微镜、掠角X射线衍射和拉曼光谱方法研究了薄膜的电镀行为、表面形貌及其结构. 结果表明,本研究中的有效光照射波长为365 nm和254 nm,415 nm的波长不足以将电子从导带激发到价带. 随着入射光波长从254 nm增加到415 nm,薄膜的厚度与结晶度均逐渐减小,波长的变化对CeO₂薄膜表面形貌的影响很小. 少量的氧气对光助阳极沉积CeO₂薄膜有积极作用,但会生成较多的铈的氧化物颗粒吸附在电极表面. 在光电化学系统中,O₂常用作电子捕获剂. 随着溶解氧含量的增加,O₂将捕获对沉积有积极作用的光生电子,进而抑制阳极沉积的反应速率.     

Mixed-phase Mesoporous TiO2 Film for High Efficiency Perovskite Solar Cells

Mesoporous scaffold structures have played great roles in halide perovskite solar cells(PSCs),due to the excellent photovoltaic performance and commercial perspective of mesoporous PSCs.Here,we reported a mixed-phase TiO2 mesoporous film as an efficient electron transport layer(ETL)for mesoporous perovskite solar cells.Due to the improved crystal phase,fihn thickness and nanopartMe size of TiO2 layer,which were controlled by varying the one-step hydrothermal reaction time and annealing time,the PSCs exhibited an outstanding short circuit photocurrent density of 25.27 mA/cm^2,and a maximum power conversion efficiency(PCE)of 19.87%.It is found that the ultra-high Jsc attributes to the excellent film quality,light capturing and excellent electron transport ability of mixed-phase TiO2 mesoporous film.The results indicate that mix-phase mesoporous metal oxide fihns could be a promising candidate for producing effective ETLs and high efficiency PSCs.     

Insight into room-temperature catalytic oxidation of NO by CrO2(110): A DFT study

The first-principles DFT calculations together with microkinetic analysis reveal the complex catalytic mechanism of low-content NO oxidation on CrO₂(110) at room temperature. It quantitatively makes clear that CrO₂(110) can exhibit considerable activity with the Mars-van-Krevelen mechanism preferred, and the nitrate species serves as the key poisoning species.     

PANI-SnP复合膜电极在镍镉废水中电控离子交换性能

采用滴涂法在铂基底制备了电活性聚苯胺-磷酸锡(PANI-SnP)复合膜电极,考察了该电极在Ni²⁺、Cd²⁺溶液的电控离子交换性能. 用傅立叶变换红外光谱和扫描电镜分析观察复合膜的组成及表面形貌;在0.1 mol·L^-1 Ni(NO₃)₂、Cd(NO₃)₂溶液,通过循环伏安法比较了PANI膜、SnP膜及PANI-SnP复合膜电极的电化学性能,并结合电化学石英晶体微天平技术重点考察了PANI-SnP复合膜的离子交换机制;同时,通过循环伏安法调控复合膜电极的氧化还原电位,结合X射线能谱和X射线光电子能谱分别测定了其氧化和还原状态的元素组成. 结果表明,PANI-SnP复合膜电极在Ni²⁺、Cd²⁺溶液均有良好的氧化还原电活性和可逆离子交换性能,其Cd²⁺离子选择性优于Ni²⁺离子,通过电控离子交换可使Cd²⁺离子从镍镉废水高效分离.     

柔性不锈钢基底上一维TiO_2纳米线薄膜的制备及表征

采用直流磁控溅射的方法在柔性不锈钢基底(50μm)上沉积纯钛薄膜,后在NaOH碱溶液中经水热法制备了非钛基大长径比的一维TiO2纳米线薄膜,并通过场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、透射电子显微镜(TEM)以及光电化学的方法对不锈钢基一维TiO2纳米线薄膜进行了表征.结果表明,纯钛薄膜的致密度、结晶性能以及与基底的结合强度均随衬底温度的升高而加强;在10mol·L-1NaOH浓度下,生长一维TiO2纳米线结构的适宜温度为130-150℃;TiO2纳米线长度达到几个微米,直径在10-30nm之间,并且相互交叉生长,构成一个三维网络结构.此外,在Na2SO4溶液中对TiO2纳米线薄膜进行了线性扫描和瞬态光电流测试,结果表明,一维TiO2纳米线薄膜电极较TiO2纳米颗粒电极表现出更优异的光电化学性能.这种磁控溅射与水热反应相结合的方法,为非钛异质基底上制备一维TiO2纳米线薄膜提供了新的思路.     

Bi1-xFexVO4薄膜光阳极的制备及光电化学性能

采用一步滴涂法在掺氟二氧化锡(FTO)导电玻璃上制备了Bi_1-xFe_xVO₄(x=0, 0.05, 0.10, 0.25, 0.40)薄膜, 表征了其结构、 形貌、 光学以及光电化学方面的性质. 结果表明, 掺入Fe后Bi_1-xFe_xVO₄薄膜的光电流密度与 BiVO₄薄膜相比均有所提高, 其中25% Fe-BiVO₄薄膜表现出最优的光电化学性能. 在0.1 mol/L磷酸缓冲溶液(pH=7.0)中, 1.23 V(vs. RHE)电势下25% Fe-BiVO₄薄膜的光电流密度为0.50 mA/cm², 与BiVO₄薄膜的0.15 mA/cm²相比提高了3倍多. 结合X射线衍射(XRD)、 拉曼光谱(Raman)和X射线光电子能谱(XPS)表征结果证实Fe³⁺以FeVO₄的形式存在于Bi_1-xFe_xVO₄薄膜中, 形成了BiVO₄/FeVO₄复合物薄膜. 紫外-可见光谱(UV-Vis)结果显示, 所有Bi_1-xFe_xVO₄薄膜的禁带宽度均为2.4~2.5 eV. 25% Fe-BiVO₄薄膜光电化学性能的提升主要归因于光生载流子转移效率(η_trans)和分离效率(η_sep)的提高. 能级结构图表明, BiVO₄和FeVO₄之间可以形成Type Ⅱ型能级结构排列, 可以促进光生载流子的分离与转移, 是25% Fe-BiVO₄薄膜光电化学性能提升的内在机理.     

Influence of Cr on the Electronic Properties of Passive Film on B30 Alloy in NaOH Solution

The influence of Cr on the electronic properties of the passive film on B30 alloy in NaOH solution was studied via electrochemical impedance spectra(EIS), potentiodynamic curve and Mott-Schottky plot. The Cr doped in the passive film on B30 alloy was detected by X-ray photoelectron spectroscopy(XPS). XPS results show that Cr₂O₃ appeared on the passive film, which implied the enhanced anti-corrosion of B30 alloy. The passive film showed a p-type semi-conductive character. The acceptor density(N_A) was in an order of magnitude of 10²² cm^-3, and N_A decreased with the increment of Cr. EIS results show that the film resistance(R_f) increased with increasing the amount of Cr. The diffusion coefficient(D₀) was calculated to be in a range of 10^-16-10^-17 cm^-2/s on the basement of point defect model(PDM).     

水分辅助对无机钙钛矿CsPbI3薄膜结晶的影响

利用水分辅助晶粒溶解重结晶策略提高全无机铯铅碘钙钛矿(CsPbI₃)薄膜的质量, 探究了退火过程中不同湿度条件对薄膜结晶质量的影响, 并从形貌结构、 缺陷复合以及光伏性能等方面进行了研究. 结果表明, 相比于相对湿度(RH)为0%组CsPbI₃薄膜明显的晶界空隙, 适当的湿度退火有助于晶粒间更致密地结合, 晶界的减少进而可抑制载流子非辐射复合; 湿度过大则会形成较粗糙的表面形貌, 影响界面接触. 实验结果表明, 7%RH下CsPbI₃薄膜中缺陷明显减少, 非辐射复合得到抑制, 载流子寿命增加; 光伏性能测试结果显示, 开路电压(V_oc)和填充因子(FF)显著增大, 并获得了15.28%的光电转换效率(PCE).     

Thin Film of Perovskite Oxide with Atomic Scale p-n Junctions

Thin films of perovskite manganese oxide La_0.66Ca_0.29K_0.05MnO₃(LCKMO) on Au/ITO(ITO=indium tin oxide) substrates were prepared by off-axis radio frequency magnetron sputtering and characterized by X-ray diffraction( XRD), high-resolution transmission electron microscopy(HRTEM), and conductive atomic force microscopy (C-AFM) at room temperature. The thin films with thickness ranged from 100 nm to 300 nm basically show cubic structures with a=0.3886 nm, the same as that of the raw material used, but the structures are highly modulated. C-AFM results revealed that the atomic scale p-n junction feature of the thin films was the same as that of the single crystals. The preparation of the thin films thus further confirms the possibility of their application extending from micrometer-sized single crystals to macroscopic thin film.     

Electronic Structure Effect of Polythiophene Derivatives and Nano N-Zn-Ag/TiO2 on Performance of Organic Thin Film Solar Cell

Nanocrystal N-Zn-Ag/TiO₂ powders were prepared with N-Zn/TiO₂ by photo deposition method. A series of pure polymers P3HT[poly(3-hexylthiophene)], P3OT[poly(3-octylthiophene)], P3DT[poly(3-decylthiophene)] and P3DDT[poly(3-dodecylthiophene)], was synthesized, which were used to synthesize p-n type semiconductor materials P3HT/N-Zn-Ag-TiO₂, P3OT/N-Zn-Ag-TiO₂, P3DT/N-Zn-Ag-TiO₂ and P3DDT/N-Zn-Ag-TiO₂ by in situ che-mical method. X-Ray diffraction(XRD) and infrared(IR) spectroscopy showed the structure of the polymers and complexes. Ultraviolet-visible(UV-Vis) spectra and cyclic voltammograms(CV) showed the optical and electronic performance of the polymers and complexes. Two new single and double organic thin film heterojunction solar cells were prepared with the above mentioned synthesized powders as raw materials. Current-voltage(I-V) measurements indicate that the conversion efficiency of the single organic thin film heterojunction solar cell is higher than that of the double organic thin film heterojunction solar cells. Single organic thin film heterojunction solar cells based on P3DT/N-Zn-Ag-TiO₂ can get a photoelectric conversion efficiency of 0.0408%. The performance of electronic transform between electron donor and acceptor on organic thin film solar cells was researched.     

Investigation of the photocatalytic degradation of organochlorine pesticides on a nano-TiO2 coated film

The photocatalytic degradation of organochlorine pesticides including -, β-, γ-, δ-hexachlorobenzene (BHC), dicofol and cypermethrin were carried out on a nano-TiO₂ coated films under UV irradiation in the air. The photocatalytic conditions, including the amount of TiO₂, irradiation time and the intensity of light were optimized. The pesticides were most effectively degraded under the condition of 2.24 mg/cm² on TiO₂ film and a 400 W UV irradiation of high-pressure mercury lamp with a wavelength of 365 nm. A typical organochlorine pesticide, 20 μg -BHC, was dipped onto the TiO₂ film surface and degraded completely within 20 min. In addition, the photocatalytic degradation pathways on the nano-TiO₂ coated film were discussed.     

Fe3+掺杂TiO2光催化降解聚乙烯薄膜的研究

以快速溶胶-凝胶法制备了纳米TiO₂光催化剂，并用Fe³⁺对其掺杂改性，在室温条件下, 用于固相光催化降解聚乙烯(PE)包装薄膜的研究. 对催化剂和薄膜进行了X衍射分析(XRD)、傅立叶红外光谱分析(FT-IR)、扫描电子显微镜(SEM)形貌观察. 结果表明， 60 W紫外光辐射240 h后， PE失重为8.43%, 锐钛矿型纳米TiO₂光催化剂使PE失重30.66%；用Fe³⁺掺杂后，0.5%Fe₂O3/TiO₂、1.0%Fe₂O₃/TiO₂和2.0%Fe₂O3/TiO₂分别使PE失重35.91%、20.72%和13.30%. 光催化剂加速了PE的失重，碳链的断裂和光氧化腐蚀，在薄膜表面形成大量的坑洞，降解产物中的小分子量的石蜡含量明显增高. Fe³⁺掺杂有一个最佳量， 0.5%Fe₂O3/TiO₂光催化降解PE的活性最高.