可见光响应的CO3(PO4)2/Ag3PO4纳米复合光催化剂的制备及表征

采用简单的化学偏聚法合成出Ag3PO4纳米颗粒、磷酸钴(Co3(PO4)2,CoP)纳米片以及它们两者的纳米复合结构(CoP/Ag3PO4),同时还比较了它们的可见光催化活性.采用场发射扫描电镜(FESEM)、X射线衍射(XRD)、紫外-可见(UV-Vis)吸收光谱以及光致发光谱等手段对其形貌、结构、光学以及可见光催化性能等进行表征.结果表明,CoP/Ag3PO4复合纳米结构的可见光降解甲基橙(MO)的速率和循环稳定性均明显优于其它两种物质.这表明CoP应该起着共催化剂的作用,它能够抑制光生电子与空穴之间的复合,并且提供大量高活性的光生空穴.此外,我们还发现CoP/Ag3PO4降解另一种阳离子型染料——罗丹明B(RhB)的能力则远不如纯Ag3PO4,这可能是与光催化剂的表面性质发生改变有关,造成更低的RhB吸附能力.本文提供了一种廉价制备高效可见光催化剂的新方法.     

LiTi2(PO4)3/C 复合材料的制备及电化学性能

采用聚乙烯醇(PVA)辅助溶胶-凝胶法合成了具有Na+超离子导体(NASICON)结构的LiTi2(PO4)3/C复合材料.运用X射线衍射(XRD)、扫描电子显微镜(SEM)、充放电测试、循环伏安(CV)、电化学阻抗谱(EIS)等对其结构形貌和电化学性能进行表征.实验结果表明:合成的LiTi2(PO4)3/C具有良好的NASICON结构,首次放电容量为144mAh·g-1.电化学阻抗谱测试结果显示,LiTi2(PO4)3/C复合材料电极在首次嵌锂过程中分别出现了代表固体电解质相界面(SEI)膜及接触阻抗、电荷传递阻抗和相变阻抗的圆弧,并详细分析了它们的变化规律.计算了Li+在LiTi2(PO4)3中嵌入/脱出时的扩散系数,分别为2.40×10-5和1.07×10-5cm2·s-1.     

Li_2CO_3添加剂对石墨电极性能的影响

运用电化学阻抗谱(EIS)和循环伏安法(CV)研究了在1mol/LLiPF6-EC(碳酸乙烯酯):DMC(碳酸二甲酯)电解液中添加Li2CO3对石墨电极性能的影响及机制.CV研究结果表明,在1mol/LLiPF6-EC:DMC电解液中添加Li2CO3能够有效抑制石墨电极首次充放电过程中碳酸乙烯酯(EC)的单电子还原过程,即还原分解产生乙烯和碳酸锂的过程,进而改善石墨电极的电化学循环性能.EIS研究结果表明,在添加Li2CO3的1mol/LLiPF6-EC:DMC电解液中,石墨电极表面的固体电解质相界面膜(SEI膜)具有较强的黏弹性,可以更好地适应锂离子嵌入过程中石墨颗粒体积的微小变化,从而使锂离子的嵌入过程更容易进行.     

Laser Damage Mechanisms of Amorphous Ta2O5 Films at 1064, 532 and 355nm in One-on-One Regime

Ta2O5 films are deposited on fused silica substrates by conventional e-beam evaporation. Surface topography and chemical composition are examined by atomic force microscopy （AFM） and x-ray photoelectron spectroscopy （XPS）. The calculation of electron structures of Ta2O5 and Ta2O5-x is attempted using a first-principle pseudopotential method within the local density approximation. The laser-induced damage threshold （LIDT） is performed at 1064, 532 and 355 nm in 1-on-1 regime, respectively. The results show that the LIDT increases with the wavelength increasing, which is in agreement with the wavelength effect. However, the LIDT results are not consistent with the empirical equation （I（λ）=aλm）, which may be attributed to the intrinsic absorption of Ta2O5 at the wavelengths of 532 or/and 355 nm. Moreover, different damage morphologies are observed when the films are irradiated at different wavelengths. It is concluded that the laser damage at 1064 nm is the defect dominant mechanism and at 355 nm it is the intrinsic absorption dominant mechanism, whereas at 532 nm it is the combined defect and intrinsic absorption dominant mechanism.     

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。     

Temperature dependences of optical properties,chemical composition,structure,and laser damage in Ta2O5 films

Ta2O5 films are prepared by e-beam evaporation with varied deposition temperatures,annealing temperatures,and annealing times.The effects of temperature on the optical properties,chemical composition,structure,and laserinduced damage threshold(LIDT) are systematically investigated.The results show that the increase of deposition temperature decreases the film transmittance slightly,yet annealing below 923 K is beneficial for the transmittance.The XRD analysis reveals that the film is in the amorphous phase when annealed below 873 K and in thehexagonal phase when annealed at 1073 K.While an interesting near-crystalline phase is found when annealed at 923 K.The LIDT increases with the deposition temperature increasing,whereas it increases firstly and then decreases as the annealing temperature increases.In addition,the increase of the annealing time from 4 h to 12 h is favourable to improving the LIDT,which is mainly due to the improvement of the O/Ta ratio.The highest LIDT film is obtained when annealed at 923 K,owing to the lowest density of defect.     

处理温度及CdS量子点对Eu3+掺杂SiO2干凝胶光致发光性质的影响

以正硅酸乙酯为原料,采用溶胶-凝胶法制备了Eu3+掺杂的SiO2凝胶和Eu3+/CdS量子点共掺杂的 SiO2干凝胶.考察了不同温度下处理2h对Eu3掺杂SiO2凝胶发光性质的影响.在40℃干燥的样品荧光光 谱中,没有出现614 nm发射峰,455 nm处的峰也很弱;随着干燥处理温度的升高,455nm和614 nm...     

Comparison of laser-induced damage in Ta2O5 and Nb2O5 single-layer films and high reflectors

Ta2O5 and Nb2O5 films are deposited on BK7 glass substrates using an electron beam evaporation method and are annealed at 673 K in the air.In this letter,comparative studies of the optical transmittance,microstructure,chemical composition,optical absorption,and laser-induced damage threshold(LIDT) of the two films are conducted.Findings indicate that the substoichiometric defect is very harmful to the laser damage resistance of Ta2O5 and Nb2O5 films.The decrease of absorption improves the LIDT in films deposited by the same material.However,although the absorption of the Ta2O5 single layer is less than that of the Nb2O5 single layer,the LIDT of the former is lower than that of the latter.High-reflective(HR) coatings have a higher LIDT than single layers due to the thermal dissipation of the SiO2 layers and the decreased electric field intensity(EFI).In addition,the Nb2O5 HR coating achieves the highest LIDT at 25.6 J/cm 2 in both single layers and HR coatings.     

Fabrication of mixed perovskite organic cation thin films via controllable cation exchange

Here in this paper, we demonstrate a facile technique for creating the mixed formamidinium(HN = CHNH_3~+, FA~+)and methylammonium(CH_3NH_3~+, MA~+) cations in the lead iodide perovskite. This technique entails a facile drop-casting of formamidinium iodide(FAI) solutions on as-prepared MAPbI_3 perovskite thin films under the controlled conditions,which leads to controllable displacement of the MA~+ cations by FA~+ cations in the perovskite structure at room temperature. Uniform and controllable mixed organic cation perovskite thin films without a "bi-layered" or graded structure are achieved. By applying this approach to photovoltaic devices, we are able to improve the performances of devices through extending their optical-absorption onset further into the infrared region to enhance solar-light harvesting. Additionally,this work provides a simple and efficient technique to tune the structural, electrical, and optoelectronic properties of the light-harvesting materials for high-performance perovskite solar cells.     

FTIR和XRD研究甲酰胺在高岭石插层复合体系中的形态及其复合物的微观结构

插层复合体系中,有机插层剂在插层的同时也可能吸附在复合物的表面或以自由态存在,对插层分子的表征将会产生较大的影响。以丙酮作淋洗剂,用FT IR及XRD技术对淋洗前后的插层复合体系监控,插层剂分子在复合体系中的可能存在形式,探讨水的作用及复合物微观结构的变化。结果显示：甲酰胺有插层、游离和吸附在复合物表面三种存在形态。3355和3462 cm -1处的红外振动峰归属于表面吸附的插层剂分子,3626 cm-1的峰归属于插层的 H2 O分子,在干燥后均消失。H2 O作为填充空间的分子参预了插层过程,且插入到层间,并在干燥后脱嵌。3534 cm -1处的振动峰在淋洗前后一直存在,是由于插层的甲酰胺分子与高岭石层间形成氢键作用的结果。以丙酮作为淋洗剂,可以选择性的消除表面吸附的甲酰胺而不影响复合物的结构。插层的甲酰胺分子以C-N键垂直于层片呈单分子层排列,并通过氨基与高岭石铝氧八面体层的内表面羟基和硅氧四面体层的氧形成了两种氢键作用。