静电纺丝法制备NiO纳米纤维及其表征

纳米级NiO因具有优良的催化和热敏等性能而被广泛用于催化剂^[1]、电池电极^[2,3]、光电转化材料^[4～6]、电化学电容器^[7～8]等诸多方面.迄今,已成功地制备出N iO的纳米颗粒^[9]、纳米线^[10]及纳米薄膜^[11],但是对于具有准一维结构的NiO纳米纤维的制备及性能研究尚未见报道.     

植物生物分子的电分析化学研究Ⅷ.秋水仙碱的微分脉冲极谱行为及分析应用

秋水仙碱是近年来新发现的有前途的抗癌植物有效成分。秋水仙碱的测定方法,如容量滴定法^[1]、电位滴定法^[2]、紫外分光光度法^[3]、荧光分析法^[4]和高效液相色谱法^[5]等,手续均不太简便。电化学分析研究秋水仙碱主要有阳极伏安法^[6]和交流极谱法^[7],前者因使用固态电极,重现性较差。后者用非水溶剂作介质,灵敏度不高。     

有机化合物结构与性能间的关系对联多苯和间联多苯

关于对位联多苯的电子光谱^[1,2]Lewis^[3]认为是属于“两类典型线摆动体”以外的一个“中间类型”,而Ferguson^[4]认为是“第一类共轭体系”的一个例外,电子光谱不能用λ²∝n或λ∝n这两个典型公式来表示.     

化学修饰电极的研究——Ⅰ.等离子体聚合法制备聚乙烯二茂铁膜电极

化学修饰电极是当前电化学领域中十分活跃的崭新研究方向^[1~4].它的出现扩展了电化学的研究和应用范围,有广阔的发展前途,已在电子转移、光电转换、催化、立体选择性有机合成以及选择富集测定等方面显出其优越性.最近,在多种化学修饰电极类型中,令人特别感兴趣的是具有电活性的聚合物膜电极.制备聚合物膜电极的方法很多^[5~10],用等离子体聚合法可得高度交联的超薄膜,且化学和热稳定性均好^[10,11].     

金微盘电极的加工和表征

微电极具有常规电极无法比拟的优良的电化学特性^[1,2].它包括单微电极和微电极阵列, 其中单微电极的整体尺寸小, 可用于微区分析研究. 目前微盘电极的工艺改善目标主要包括: 电极整体尺寸小、 电极材料和绝缘层之间的粘附性高及电极具有明确的和可重复的形状和尺寸等^[3]方面.     

发光多孔硅表面的STM研究

自从Canham首次报道了室温下多孔硅的光致发光现象以来^[1],多孔硅已成为半导体光电化学及材料领域内最为热门的研究课题^[2].     

零电流示波电位滴定盐酸异丙嗪

盐酸异丙嗪是一种较重要的抗组胺药,现行的分析标准为非水滴定法^[1],此外尚有分光光度法^[2]、伏安法^[3]、电极法^[4]、液相色谱法^[5]和流动注射分析法^[6]等。本文将高鸿提出的零电流示波电位滴定法^[7]中的铂片电极修饰一层含四苯基硼酸-异丙嗪电活性物质的PVC膜,使电极对异丙嗪产生响应,可用于四苯基硼酸钠直接滴定异丙嗪的终点指示。     

电极防吸附膜研究

在电化学分析及电极过程动力学研究中,表面活性物质在电极上的吸附,常使测量结果受到严重影响^[1,2]。在天然水的反向极谱分析中,由于天然水,特别是海水,含有大量表面活性物质及悬浮体,并且分析溶液又进行搅拌,因此对电极的灵敏度及重演性影响特别严重^[3-5]。用汞膜电极测定一个新采集的海水样品后,即需重新涂汞^[3,4]。     

锌电极电化学行为Ⅵ.锌粉在碱性电解液中的电化学腐蚀

锌电极是广泛使用于一次和二次电池中的阳极材料. 在二次电池中主要是以锌粉作为电极材料. 长期以来,由于锌粉电极在充放电过程中发生形变和枝晶生长等^[1],致使它组成的二 次电池循环寿命差. 为了研究锌粉在碱性电解液中的腐蚀行为,人们通常是使用锌盘电极来模拟锌粉的情况^[2]. 但是锌盘与锌粉不同. 为此,我们采用电解沉积锌粉于锌盘电极上,制成 粉状电极研究锌粉在碱性溶液中的腐蚀行为及一些非离子型有机缓蚀剂对锌粉的缓蚀作用     

菁染料单分子膜覆盖的铂电极的电化学特性

L-B膜作为一种单分子膜技术已经得到了广泛的应用。最近很多人用电化学方法研究覆盖有L-B膜电极的特性^[1,2]。许多工作^[3-5]证明了脂肪酸L-B膜具有很强的抑制离子透过和抑制电子隧道电流的能力。     

利用TiO_2薄膜光催化降解苯酚(英文)

利用化学气相沉积法制备ＴｉＯ_２Ｗ薄膜,在光催化下降解苯酚溶液。研究结果表明,薄膜沉积条件与降解速率有关,且用硅片作底物,薄膜为锐态晶型时其降解苯酚速率最高。利用光电催化比只用光催化降解苯酚速率高约１０％。用紫外光照射３０分钟,苯酚最大可转化７４％。     

纳米结构ZnO/染料/聚吡咯光阳极的光电化学性质

用光电化学方法研究了染料RuL2 (NCS) 2 (L =2 ,2′ bipydine 4,4′ dicarboxylicacid) (简写为Dye)、聚吡咯 (PPy)敏化氧化锌 (ZnO)纳米晶电极以及用RuL2 (NCS) 2 和PPy复合敏化ZnO纳米晶膜电极的光电化学行为 .实验表明 ,ZnO/PPy纳米多孔膜电极为双层n 型半导体结构 .PPy和RuL2(NCS) 2 都可对ZnO纳米晶膜产生敏化作用 ,ZnO/RuL2 (NCS) 2 /PPy复合多孔膜电极产生的光电流远大于ZnO/PPy纳米多孔膜电极和ZnO/Dye多孔膜电极产生的光电流 .讨论了该电极的光生电子的机理 ,初步测定了ZnO/RuL2 (NCS) 2 /PPy电极作为光阳极的光电化学电池的工作特性曲线 ,测得该电池的光电转换效率为 1 .3% ,填充因子为 0 .75 .     

Enhancement of Storage Capacity and Conversion Efficiency of Photoelectrochemical Cells: Effect of Dyes Adsorbed on Carbon Nano Tubes

We report here our studies on photoelectrochemical (PEC) cells where two commonly used photosensitive dyes, thionine and Rose Bengal were used as photosensitizers for conversion of light energy to electrical energy. The performance of the cells increased radically in presence of oxidized multiwalled carbon nano tubes (OMWCNTs) as reflected by the values of conversion efficiency (∼3.69%) and open circuit voltage (∼548.9 mV). To understand the role of OMWCNTs in enhancing the performance of the cells, the spectral study of dye–OMWCNT mixed systems were performed. The absorption spectra indicated more absorption of incident photons in presence of OMWCNT, whereas the infrared spectra suggested that the basic structure of dyes remained unaltered. The spectral studies implied that the dye molecules got adsorbed on OMWCNTs side walls causing efficient absorption of the incident light quanta. Moreover, insertion of planar lipid membrane (PLM) separating the two chambers of PEC cell could effectively counteract the recombination of photodissociated charges and thereby caused better storage capacity of the PEC cells with further increase in efficiency.     

TiO_2/CuPc/NiFe-LDH photoanode for efficient photoelectrochemical water splitting

Photoelectrochemical(PEC) water splitting is a promising approach for renewable hydrogen production.However,the practical PEC solar-to-fuel conversion efficiency is still low owing to poor light absorption and rapid recombination of charge carriers in photoelectrode.In this work,we report a ternary photoanode with simultaneously enhancement of light absorption and water oxidation efficiency by introducing copper phthalocyanine(CuPc) and nickel iron-laye red double hydroxide(NiFe-LDH) on TiO_2(denoted as TiO_2/CuPc/NiFe-LDH).An experimental study reveals that CuPc loading on TiO_2 bring strong visible light absorption;NiFe-LDH as an oxygen evolution reaction catalyst efficiently accelerates the surface water oxidation reaction.This synergistic effect of CuPc and NiFe-LDH gives enhanced photocurrent density(2.10 mA/cm2 at 0.6 V vs.SCE) and excellent stability in the ternary TiO_2/CuPc/NiFeLDH photoanode.     

构筑先进二维异质结构Ag/WO3−x用于提升光电转化效率

Solar energy, which is clean, affordable and reliable, can help alleviate the current environmental pollution and energy crisis efficiently. In the past few decades, great progress has been made in harvesting and converting solar energy into chemical energy. Among various technologies, plasmon-induced photoelectrochemistry has been proposed as a promising alternative for solar energy conversion. The hot electrons generated from plasmon excitation and transfer from metal nanostructures to semiconductors is a potential new paradigm for solar energy conversion. However, the ultrafast decay of the hot carriers is unfavorable for the improvement of photocatalytic efficiency. Therefore, finding more efficient photocatalysts, with enhanced light absorption and a longer carrier lifetime, is of paramount importance for improving the conversion efficiency of solar energy, but their fabrication is challenging. In this work, a plasmonic metal/semiconductor heterostructure based on Ag nanoparticles embedded in two-dimensional (2D) amorphous sub-stoichiometric tungsten trioxide (a-WO_3−x), followed by annealing, was successfully fabricated. Firstly, the peculiar nanostructure of 2D a-WO_3−x was successfully constructed from WS₂ nanosheets with supercritical CO₂ (SC CO₂) at 200 ℃. Secondly, the Ag/a-WO_3−x heterostructure was synthesized using an in situ reduction method. Finally, the obtained 2D heterostructure of Ag/WO_3−x was annealed at 400 ℃ in N₂ to further improve its stability and conductivity. X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure, morphology, and composition of the material, respectively. UV-Vis spectra were also measured to evaluate light adsorption. Characterization results show that the amorphous structure can effectively anchor metal nanoparticles, and the metal nanoparticles are uniformly dispersed in the amorphous region and have a small size. The as-prepared nanocomposites showed efficient photoelectrochemical (PEC) water splitting when serving as photoelectrode materials, and efficient PEC activity towards photo-oxidation degradation currents under excitation of Ag localized surface plasmon resonance (LSPR). The photocurrent response of the Ag/WO_3−x heterostructure was approximately five times greater than that of a-WO_3−x. Moreover, the PEC degradation efficiency of Ag/WO_3−x reached 96.7% for MO under Vis light illumination (after reaction for 120 min), while the PEC degradation efficiency of WO_3−x was only 63.6%. The high PEC performance of the composite photoanode can be ascribed to the local surface plasmon resonance (LSPR) effect of the Ag nanoparticles, which can enhance the light absorption and hot electron transformation. Moreover, the construction of local crystalline-amorphous interfaces can further promote the separation efficiency of the photogenerated electron-hole pairs, and thus increase conductivity. This work provides a positive strategy for the fabrication of advanced photocatalysts, and a new perspective on understanding of the synergistic effects of structural and electronic regulations.     

提高氧化铁光电催化分解水效率的策略进展

为了解决能源危机与环境污染问题,发展一种可再生的清洁能源至关重要.太阳能是一种取之不尽用之不竭的清洁能源,而氢气是一种良好的能源载体.利用太阳能光电催化水分解制氢,是一项有望能够解决能源与环境问题的技术,具有很大的应用前景.其中,氧化铁因为具有合适的能带位置与带隙、良好的稳定性与廉价无毒等优点,成为一种理想的光阳极材料.但是,在实际的测试中,氧化铁仅仅只能得到一个较低的光电转换效率,这可能是因为其较短的空穴扩散距离、较低的电导率以及极度缓慢的水氧化反应动力学所致.整个光电催化水氧化可分为三个过程,即光吸收过程、电荷分离过程以及表面空穴注入过程.这三个过程的效率共同决定了器件的太阳能转化效率.鉴于此,本文将从如何提高这三个效率的角度出发,总结近期研究报道中提高氧化铁光电催化分解水效率的一些策略.光吸收过程是指半导体中价带的电子在吸收具有一定能量的光子后发生跃迁,产生空穴-电子对的过程.其光子的损失主要来源于光的反射、透射以及半导体吸收边的限制.提高光吸收效率的主要策略包括制备具有特定纳米结构的氧化铁电极、利用表面等离子体共振效应以及组成双光吸收系统和掺杂等.电荷分离过程指的是受光激发产生的空穴电子对,在内建电场的作用下发生电荷分离,即光生空穴流向电极表面,光生电子流向半导体内部并从外电路导出.电荷分离效率的损失主要来源于光生载流子在迁移过程中的复合.因此,为了提高电荷分离效率,常见的策略是提高载流子在电荷分离过程中的复合时间τ₁和减少电荷迁移到表面(空穴)或者基底(电子)的时间τ₂.具体的策略包括制备特定的纳米结构(缩短体表相距离,减少τ₂)、构建异质结(增强能带弯曲,提高τ₁和减少τ₂)、掺杂(减少τ₂)和钝化复合中心(提高τ₁)等.表面空穴注入是指到达表面的光生空穴发生水氧化反应生成氧气的过程.除了空穴注入外,表面还可能存在复合与逆反应过程.因此,为了提高表面空穴注入效率,我们既可以提高水氧化反应动力学,具体的手段包括引入水氧化催化剂、F掺杂和碱处理等;也可以采用减少复合反应的策略,具体的方法包括引入钝化层、酸处理和高温热处理等;还可以采用减少逆反应的方法,最常见的手段就是在基底与氧化铁层之间引入电子阻挡层.上述三种途径都能提高表面空穴注入效率.最后,通过结合上述的一些策略,目前得到的最高性能的氧化铁电极在1.23 V(相对于可逆氢电极)能够达到6 mA cm^?2的光电催化分解水电流,但这个值依然明显低于氧化铁的理论值(12.6 mA cm^?2).这可能是由于体相复合所致.除此之外,氧化铁表面的水氧化机理现在依然不清晰,这些都是需要我们在未来解决的问题.     

Quantum dots sensitized graphene: In situ growth and application in photoelectrochemical cells

A novel photoelectrochemical cells (PEC) based on quantum dots (QDs) sensitized graphene for light harvesting and energy conversion was described in this work. QDs sensitized graphene was prepared by in situ growth of QDs on noncovalently functionalized graphene. QDs sensitized graphene photoelectrodes showed enhanced photocurrent generation capability and incident photon-to-electron conversion efficiency (IPCE) at visible light, and could also be an efficient platform for other optoelectronic applications.     

Photoelectrochemical Reduction of Carbon Dioxide to Methanol through a Highly Efficient Enzyme Cascade

Natural photosynthesis is an effective route for the clean and sustainable conversion of CO₂ into high‐energy chemicals. Inspired by the natural process, a tandem photoelectrochemical (PEC) cell with an integrated enzyme‐cascade (TPIEC) system was designed, which transfers photogenerated electrons to a multienzyme cascade for the biocatalyzed reduction of CO₂ to methanol. A hematite photoanode and a bismuth ferrite photocathode were applied to fabricate the iron oxide based tandem PEC cell for visible‐light‐assisted regeneration of the nicotinamide cofactor (NADH). The cell utilized water as an electron donor and spontaneously regenerated NADH. To complete the TPIEC system, a superior three‐dehydrogenase cascade system was employed in the cathodic part of the PEC cell. Under applied bias, the TPIEC system achieved a high methanol conversion output of 220 μm h⁻¹, 1280 μmol g⁻¹ h⁻¹ using readily available solar energy and water.     

Fabrication of 2D photonic crystals using block copolymer patterns on as grown LEDs

Di-block copolymer polystyrene-block-polymethyl methacrylate (PS-b-PMMA) was used to make patterns over a large area of as grown LEDs. The polymer patterns on LEDs surface could be transferred to the underlying p-GaN, the topmost layer of as grown LEDs by both reactive ion etching (RIE) and photo-enhanced chemical (PEC) etching. Removal of remaining polymer chains results in patterned LEDs which shows higher light extraction efficiency. In our experiment, much higher intensity for patterned LEDs in both photoluminescence (PL) and electroluminescence (EL) data plot were found. Similar improvements were found in I-V and L-I curves for patterned LEDs.     

Construction of Er3+:YAlO3/RGO/TiO2 Hybrid Electrode with Enhanced Photoelectrocatalytic Performance in Methylene Blue Degradation Under Visible Light

Much attention has been paid on doping TiO₂ to narrow its band gap to promote the absorption of visible light and restrain the recombination of electron–hole pairs to improve its efficiency in photoelectrocatalysis (PEC) under visible‐light irradiation. However, the oxidation potential energy of photo‐induced holes for the modified catalysts by visible‐light excitation is lower than that without modification by UV excitation. In this work, we synthesized a co‐coupled TiO₂ electrode (denoted ERT) with the Er³⁺:YAlO₃ and reduced graphene oxide (RGO), achieving the synergetic effect of visible‐light‐to‐UV up‐conversion and response and great electron transfer ability. The effects of external bias voltage, electrolyte concentration and pH on the PEC activity were studied with the methylene blue (MB) as the target pollutant. The results indicated that PEC by the ERT electrode showed the highest MB removal compared with those by the electrodes coupled with RGO or Er³⁺:YAlO₃ alone. In addition, the kinetic rate constant of the PEC process using the ERT electrode was higher than the sum of those of the photocatalytic and electrocatalytic processes. The optimal conditions for PEC by the ERT electrode were an external bias voltage of 1.0 V, 0.1 mol L^?1 Na₂SO₄ and pH = 10.