Controlling Reversible Expansion of Li2O2 Formation and Decomposition by Modifying Electrolyte in Li-O2 Batteries

锂空电池分别使用空气中的氧气和金属锂作为正负极活性材料，具有极高的能量密度。但是，这一体系尚不能实现商业化的应用，其中一些关键问题未能解决。由于其正极活性材料是气体，使得电化学反应涉及气-液-固三相界面，电极过程十分复杂。与其它二次电池相比，空气电极需要考虑结构因素和催化因素。不仅要改善氧气电化学反应的动力学迟缓问题，还要考虑放电产物的驻留空间问题。董全峰教授课题组在前期开展了基于空气电极固相表面电催化研究，并结合电极结构方面的问题，构筑了有利于氧气发生反应的仿生开放式结构电极。 该研究工作主要由化学化工学院2015级iChEM直博生林晓东（第一作者）在董全峰教授、郑明森副教授和龚磊副教授的共同指导下完成，理论计算由袁汝明助理教授（共同第一作者）完成，曹勇、丁晓兵、蔡森荣、韩博闻等学生参与了部分工作。周志有教授和洪宇浩博士生在电化学微分质谱方面给予大力的帮助与支持。【Abstract】The aprotic lithium-oxygen (Li-O2) battery has attracted worldwide attention because of its ultrahigh theoretical energy density. However, its practical application is critically hindered by cathode passivation, large polarization, and severe parasitic reactions. Here, we demonstrate an originally designed Ru(Ⅱ) polypyridyl complex (RuPC) though which the reversible expansion of Li2O2 formation and decomposition can be achieved in Li-O2 batteries. Experimental and theoretical results revealed that the RuPC can not only expand the formation of Li2O2 in electrolyte but also suppress the reactivity of LiO2 intermediate during discharge, thus alleviating the cathode passivation and parasitic reactions significantly. In addition, an initial delithiation pathway can be achieved when charging in turn; thus, the Li2O2 products can be decomposed reversibly with a low overpotential. Consequently, the RuPC-catalyzed Li-O2 batteries exhibited a high discharge capacity, a low charge overpotential, and an ultralong cycle life. This work provides an alternative way of designing the soluble organic catalysts for metal-O2 batteries.This work was supported by the National 973 Program (2015CB251102), the Key Project of National Natural Science Foundation of China (21673196, 21621091, 21703186, 21773192),and the Fundamental Research Funds for the Central Universities (20720150042,20720150043). The authors thank Prof. Eric Meggers at Philipps-Univeristaet Marburg for his discussion about the synthesis of RuPC complex; Prof. Gang Fu at Xiamen University for his instructive discussions in DFT calculations; Lajia Yu and Dandan Tao at Xiamen University for their assistance in EPR experiments and UV-Vis spectroscopy experiments, respectively; and Yu Gu and Tao Wang at Xiamen University for their discussions in XPS results and CV data,respectively. 该工作得到科技部重大基础研究计划（项目批准号：2015CB251102）、国家自然科学基金（项目批准号：21673196、21621091、21703186、21773192）和中央高校基本科研业务费专项资金（项目批准号：20720150042、20720150043）的资助。 此外，感谢傅钢教授在理论计算方面的讨论和建议，Eric Meggers教授在配合物合成上的讨论，泉州师范学院吴启辉教授和化学化工学院谷宇博士生在X射线光电子能谱方面的帮助，于腊佳老师在电子顺磁共振实验上的帮助，陶丹丹博士生在紫外可见光谱测试上的帮助以及王韬博士生在循环伏安方面的讨论

殺蟲劑及殺菌劑對感染甜菜夜蛾黑殭菌之影響

不同劑型殺蟲劑混合在培養基內及孢子懸浮液中對黑疆菌(Metarhizium anisopliae; Ma-2)影響不一，對孢子發芽、菌絲生長、產孢抑制程度也不同。 具殺蟲能力之殺蟲劑 EPN、Bifenthrin Chlorpyrifos 在Ma-2接種 24、48 小時後處 理，可減少甜菜夜蛾(Sposopteraexigua)幼蟲為害滿天星葉面積達10倍以上，而不影 響已感染Ma-2之產孢。推薦濃度之Methomyl對甜菜夜蛾幼蟲致死作用不佳，但與 Ma- 2 孢子懸浮液混合具協力作用，除減輕受害程度外，亦可縮短該蟲被Ma-2感染至死亡 時間。 殺菌劑中Mancozeb 、Curzate、 Carbendazin 、Metalyxyl、 Benomyl、對 Ma-2 毒 性極強。甜菜夜蛾幼蟲自2 齡初餵以五種殺菌劑處理過之滿天星葉，至4 齡時，Man- cozeb 及Curzate 處理組對Ma-2之感病率明顯降低，但在Ma-2已感染後24小時處理， 則不影響其產孢。取食含 Benomyl、 Carbendazin、Metalyxyl 之處理，不改變對Ma -2之感病率。惟 Benomyl、 Carbendazin與孢子懸浮液混合20分鐘後，明顯抑制其致 病率。以UV、誘變劑處理極易獲得抗Benomyl 、Carbendazin 菌株(UV-Ba、 UV-Be、 MU-Ba、 MU-Be) ，菌株間有交互抗性，且抗藥性穩定，對甜菜夜蛾幼蟲致病力也有 差異殺蟲作用較佳之UV-Be 菌株其Lipolytic enzyme作用較強。逐漸提高培養基中之 Benomyl、 Carbendazin 亦可獲得抗藥性菌株(Fe-Be、 Fe-Ba) ，但Fe-Ba 抗性不穩 定，以2 代不含藥劑PDA 接移後即喪失。各抗藥性菌株菌落生長均較母株差，惟Fe-B a菌落在抗藥性喪失同時，菌絲生長速度恢復與母株相同

未飽和含水層之污染物傳輸模式

垃圾掩埋場因降雨、有機物水解或其他因素常產生大量滲出水，而其通常含有重金屬 、有機化學物質或其他毒性污染物質，當此等污染物藉由滲出水流經未飽和含水層後 ，即污染了地下水源。以往的文獻對於此類地下水污染問題雖曾提出了多種不同的模 式 (主要包括了數值模式及數學解析模式兩大類 )，然而此等模式多極為複雜且針對 某些特定情況而建立，并非完整的探討了地下水污染傳輸行為。本研究乃致力於探討 當污染物隨著滲出水流經未飽和含水層時，污染物在土壤中的傳輸特性，而污染物的 傳輸特性受土壤中孔流速度 (pore water velocity)的影響效應，亦於本研究中考慮 之，以建立較為廣泛之未飽和含水層中地下水污染傳輸模式。本文采用一維垂直水流 方程式及溶質傳輸方程式，輔以適當的初始條件及邊界條件，并以數學解析的方法， 建立污染物在未飽和含水層中的傳輸模式。本研究之解析乃擴展 Philip (1957)提出 的冪級數展開法，分別應用於含重力項之一維水流及溶質傳輸方程式，本模式并探討 延散係數(dispersion coefficient)為土壤中孔流速度或純粹為含水量(water cont- ent)的函數時，污染物於土壤中分佈情況的異同。由本文之結果，土壤中除含水量因 素外，孔流速度及重力效應對污染物之傳輸有顯著之影響。本模式的建立，將有助於 了解和預估地下水源受到的污染程度

A study on the compressiblity properties of high embankment

夯實土壤已大量用於道路路基與其他填土施工，這些結構物對邊坡破環總是主要考慮 因素，且在大部份情況下，其為實際設計中唯一考慮之標準。然近年來高度較大這路 基施工已相當普遍，故除路基穩定之基本考慮外，壓縮性之考量亦不容忽視。因此， 釐訂夯實步驟以求路基之短期與長期沉陷能被預測與控制之重要性與日俱增。 本文旨在研究高填土路基之壓縮行為。藉由一系列之壓密試驗以探討夯實含水量、 乾密度、夯實壓力與垂直應力大小等因素，對一中等塑性之殘留黏土於擬夯實與浸水 情況時壓縮行為之影響。夯實土壤系於實驗室中以揉壓式自動夯實機準備。擬夯實土 壤之壓縮性系由實驗室壓密儀測定，主要在於探討夯實過程中所產生之夯實預壓力。 為模擬土壤路基受長期環境因素之影響。夯實土壤於不同路基荷重下浸濕并加反水壓 飽和，目的在於觀察路基於不同荷重作用下浸濕所引發之體積變化。 研究顯示：於最佳含水量乾側夯實所得試體較濕側夯實所得試體具較高之預壓力。此 外，對於所考慮之部份飽和與夯實壓力範圍而言，歷實預壓力對夯實壓力之比值小於 1 ，該結果亦指出飽和時發生之體積變化可能受夯實預壓力之影響。至於浸水土壤之 壓縮行為，由結果可知其與路基荷重大小與飽和時所產生之巨觀結構有關。將試驗獲 得之重要夯實變數進行統計分析，建立出夯實預壓力與浸濕所引發之體積變化之最佳 預估模式。初始含水量與夯實壓力乃影響夯實預壓力反應之主要因素；而初始孔隙比 與路基荷重大小則為影響浸濕所引發之體積變化反應之主要因素。利用導出之預估方 程式即可預測與控制該填土路基於擬夯實與浸水情況之壓縮性

Symmetrically abrupt GaN/AlGaN superlattices by alternative interface-interruption scheme

973 program [2012CB619301, 2011CB925600]; "863" program [2011AA03A111]; FRFCU [2012121011, 2011121042]; National Natural Science Foundation; Science & technology program of Fujian of China; Science & technology program of Xiamen of ChinaWe report an alternative interruption scheme to effectively improve the abruptness of GaN/AlGaN superlattices by minimizing the asymmetric feature of different types of heterointerfaces. It is found by x-ray diffraction that the interface abruptness is degraded and the GaN thickness is reduced with the interruption time increasing. Detailed investigation with scanning transmission electron microscopy demonstrates that the Al diffusion and the interface etching effect at the GaN/AlGaN interface are the critical reasons leading to the interfacial asymmetry. An alternative interface-interruption scheme is then proposed to enhance the abruptness of the superlattice interfaces, and consequently, the emission efficiency can also be significantly enhanced

Low-Temperature ZnO TFTs Fabricated by Reactive Sputtering of Metallic Zinc Target

<p>A low-temperature metallic-zinc-target reactive sputtering technology is used to fabricate a ZnO thin-film transistor (TFT). The effect of the $hbox{O}_{2}/hbox{Ar}$ flow rate ratio on the performance of the resulting TFTs is investigated in detail. It is found that an $hbox{O}_{2}/hbox{Ar}$ ratio of 0.75&ndash;0.8 produces devices with the best performance. The maximum processing temperature used in this brief is 150 $^{circ}hbox{C}$, and the fabricated TFTs have a saturation mobility of 7.4 $hbox{cm}^{2}/(hbox{V}cdot hbox{s})$, an on&ndash;off current ratio of more than $hbox{1} times hbox{10}^{7}$ , and a subthreshold swing of 0.58 V/dec. Experimental results also show that using $hbox{SiO}_{x}$ as gate dielectric instead of $hbox{SiN}_{x}$ can improve both carrier mobility and subthreshold.</p

Simultaneous determination of dissolved indene, naphthalene and phenanthrene in aqueous solution by dual-wavelength fluorescent technique

A novel method was deveolped for the simultaneous determination of polycyclic. aromatic hydrocarbons in interfering multicomponents system in water. The concentrations of indene, naphthalene and phenanthrene in water have been determined directly by using dual-wavelength fluorescence-spectrometry with 3D technique which was used to optimize detection points and reference-wavelenth to eliminate the interference of other components. The point A(lambda(ex) = 250.0 nm, lambda(em) = 308.0 nm), B (lambda(ex) = 225.0 nm, lambda(em) = 335.0 nm) and C (lambda(ex) = 250.0 nm, lambda(em) = 364.0 nm) were chosen as the detection point of indene, naphthalene and phenanthrene, while the wavelengths of 292.5 nm and 286.7 nm were used as the reference-wavelength. The linear ranges for the determination of indene, naphthalene and phenanthrene were 2.00 x 10(-7) -2.00 x 10(-5) mol/L, 5.00 x 10(-8) -3.50 x 10(-6) mol/L and 1.00 x 10(-8) -1.00 x 10(-6) mol/L, respectively. The detection limits were 8.63 x 10(-9)mol/L, 1.01 x 10(-8) mol/L and 5.29 x 10(-10) mol/L with the RSD of 1.1%, 1.0% and 0.7% (n = 7), respectively. Satisfactory results were obtained for the determination of dissolved indene, naphthalene and phenanthrene in tap water and sea water

Synergistically reinforced lithium storage performance of in situ chemically grown silicon@silicon oxide core-shell nanowires on three-dimensional conductive graphitic scaffolds

The silicon material is the most promising candidate for developing new-generation lithium-ion batteries with high energy and power output. However, there remains a significant challenge due to poor electrical conductivity and pulverization of the silicon based anode during cycles. Aiming to solve these problems, in this work we fabricate a novel 3D composite architecture made of a Si@SiOx core-shell nanowire array grown on a 3D graphitic foam (Si CNW-3D GF) substrate by a well-designed multiple-step approach. The prepared Si CNW-3D GF composite shows the integrated advantages for high-performance lithium ion batteries, including its light weight, open macroporosity, high conductivity, high Si NW loading, excellent flexibility as well as SiO x buffer layers. As a result, the Si CNW-3D GF composite exhibits excellent performance such as high reversible lithium storage capacity (3603 mA h g-1 at a current density of 840 mA g-1), excellent cycling performance (up to 100 cycles) and superior rate capability (2299 mA h g-1 at 4200 mA g-1 and 1206 mA h g-1 at 8400 mA g-1), which is 2 times that of the Si CNW electrode where Si CNWs were grown directly on a stainless steel current collector without the presence of 3D GF. This journal is ? the Partner Organisations 2014