Name: assessment of boron doped diamond electrode quality and application to in situ modification of local ph by water electrolysis
Uploaded: 2016-01-06T13:00:01.000+00:00
Duration: 13 min 9 s
Description: Watch this Scientific Journal Video about Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis at JoVE.com

我们要感谢乔纳森·纽兰博士在图4B的照片，处理光学显微镜图像，视频，珍妮弗小姐韦伯对接触角测量的建议和视觉效果，吴诗贤谭为溶剂的窗口，如图2B数据，马克西姆约瑟夫博士的建议拉曼光谱，和华威电化学和接口组的成员也谁帮助开发这里所描述的协议。我们还要感谢约瑟夫·马克斯，Lingcong猛，佐伊·艾尔斯和罗伊Meyler他们参与拍摄的协议。

注:BDD电极使用化学气相沉积技术，附着到生长衬底最常用生长。它们离开生长室氢终止（疏水的）。如果种植足够厚的BDD可以从基底被删除，被称为独立。自由站立的BDD生长表面通常抛光以显著减少表面粗糙度。清洗BDD中酸的结果在氧（O）封端的表面。 1.酸洗BDD <ol><li>放置浓硫酸的烧杯中（H 2 SO 4;约2ml或足够深，以覆盖金刚石）在热板上在RT并插入BDD。 </li><li>添加硝酸钾（KNO 3），直到它不再溶解（〜0.5克在2毫升）中，然后盖用表玻璃，并加热到〜300℃，溶液会变成褐色，因为它加热和硝酸钾会溶解。 小心处理热酸时要小心！;橡胶手套，安全摹lasses和实验室外套应该磨损，这个过程应该在通风橱中进行。 </li><li>离开加热至少30分钟或直到不再有任何棕色到该溶液中，然后关闭加热板，并留下该溶液冷却至室温。 </li><li>小心稀释在RT中水处置酸和冲洗BDD用蒸馏水。 </li><li>测量表面接触角，见1.2。疏水性（H-终止）20,21电极已经报道的接触角范围为60-90°3，其显著降低作为表面通过O形端接变得亲水。 </li><li> （可选的替代方法）对于非常薄的膜电极（附着到生长衬底，并使用上述处理，以避免薄膜脱层），洗一次，用2-丙醇和两次去离子水中在超声浴中。然后，通过以下三个清洗步骤一（1）在10mA厘米阳极极化金刚石30分钟<sup&gt; -2在1M高氯酸在40℃22;或（2）阳极极化金刚石20分钟在10mA cm -2的在1M硝酸，随后阴极极化在10mA cm -2的另外20分钟，在相同的溶液23或; （3）在循环0.1 MH 2 SO 4 2 V之间的金刚石直到一个稳定的电化学信号达到7。步骤1.4按照此。 </li></ol> 2.接触角测量<ol><li>上放置的接触角分析仪的样品台的金刚石，确保它是平坦的。放置一个1ml注射器在上面的样品台的定位，固定的针上的末端。填充去离子水的注射器。 </li><li>使用的z控制器以降低注射器到样品， 使用 x - 和 y -控制器和相机/照明器对准上述钻石的中心的注射器。 </li><li>使用分析软件分配重复1微升volum西文水出注射器，直至液滴形式在针的尖端，在摄像机图像（从未超过10微升）上可见。降低针沉积液滴上的表面，并调整为最大对比度的照明。 </li><li>收集的图像和应用墨滴形状分析软件，使用圆锥曲线的方法。单击"查找基线"的软件，然后单击"计算"，其次是"切"。 注:此过程检测基线和适合圆锥式的（椭圆形）墨滴形状;的接触角 θ，被描绘在基线和切线三相接触点之间。 </li></ol> 3. BDD材料特性<ol><li>拉曼分析SP 2 / SP 3含量 <ol><li>开展拉曼（见参考文献14指导，以实用的拉曼光谱）在BDD电极的几个不同的领域，24采用了514.5nm的或532纳米的激光，它强调SP 2的含量，提倡。 </li><li>打开微拉曼光谱仪，并允许约30分钟的CCD探测器冷却下来。检查合适的镜头，衍射光栅和过滤器在地方与选择的激光使用。 </li><li>校准使用硅（Si）的校准样品的系统。放置在仪器室中的Si衬底和光学注重与显微镜的样品。关上了大门室。切换到激光视图，并检查激光光斑是明确界定和循环。校准使用该软件，点击"工具"，其次是"校准"，然后"快速校准"，然后"确定"。 </li><li>从腔室中取出Si衬底和替换与BDD电极。光学关注感兴趣的区域中的显微镜，切换到激光视图并打开活门，检查激光聚焦。关闭快门。 </li><li>以拉曼测试使用的软件; CLICK"测量"，然后"新的"，然后"光谱采集"。设置测量波数范围，以覆盖感兴趣的特征，对于BDD这是200 -一八零零-1;设置扫描采集时间（&lt;10秒）;设置激光功率为100％（对于BDD）和;设定累计的数目（重复扫描）到五（对BDD）。如果所得到的频谱很嘈杂更累积可能是必要的。按运行并保存生成的频谱进行分析。采取拉曼是在使用实况视频进行的区域的照片。图像保存为参考。 </li><li>观察峰〜一千三百三十二-1在频谱表示sp 3键的金刚石（图1）;更广泛的峰值目前3.25的更多的缺陷。 </li><li>观察到任何NDC -由一个宽G的峰值集中在1，575 -1 26所指出的，在光谱（图1A和1B），源自成对sp。的拉伸&lt;SUP&gt; 2点;越大的峰强度越NDC本。 注:由SP 2 C形成的π键比SP 3σ键更加极化和可见激光的共振增强，从而导致更广泛，更占优势，G峰25。需要注意的是用于执行分析的确切方法可以不同的仪器和软件之间变化。 </li></ol></li></ol> 4.电化学性能<ol><li>准备欧姆接触<ol><li>独立式BDD <ol><li>使用标准技术溅射（或蒸发）的BDD的背面用钛（Ti）/金（Au）为10nm / 300nm的，用低于1×10 -5毫巴溅镀/蒸发器的压力下。如果三个目标源是可用的，更理想为Ti为10nm /铂（Pt）为10nm / Au的300nm至避免钛扩散到Au等。 </li><li>退火5小时，在400℃（大气压）使钛以形成碳化钛，crucIAL用于形成欧姆接触27。 注意:如果该BDD的背面是高度抛光（〜毫微米粗糙度），那么它是优选粗糙化之前的表面以溅射沉积，以确保更健壮的涂层。这可以通过以下方式实现，例如，低功率激光微机械加工的表面（除去&lt;30微米的材料）。 </li></ol></li><li>生长在导电衬底上的薄膜的钻石<ol><li>溅射/如上蒸发，但顶面，使用荫罩轻轻地放在在顶面上，以避免顶整个电极接触。 要么 </li><li>划伤用钻石头笔的导电衬底的背面。然后涂上导电银浆料或画上一层薄薄的小画笔类似的导电漆划痕处。最后，电通过将铜线导电环氧树脂连接。 注:有多种方式选举后编写BDD如在参考文献4中所述，例如，如果BDD可以加工成更小的结构，密封在玻璃或环氧树脂，或如果仍然附着到晶片夹紧/附加的电化学电池顶端表面rical接触。 </li></ol></li></ol></li><li>电容测量<ol><li>通过称量0.20克在双蒸馏水制备20毫升的0.1M KNO 3溶液（此水质在整个推荐，电阻率18.2MΩ厘米）。清洁无论是氧化铝抛光或电化学循环稀酸在使用前电极（见注1）16,23,28。 </li><li>为0.1V秒，使用运行循环伏安（CVS）恒电位-1之间-0.1 V和0.1伏，从0开始为V，BDD作为工作电极相对于公共参考电极，例如银/氯化银（银/氯化银）或饱和甘汞电极（SCE），和一个铂反电极。分析第二个CV。 注: 图2A </strong&gt;显示记录的一个独立的金属典型的电容曲线掺杂BDD电极。 </li><li>由2测量在0V从所记录的电容曲线和除法的总电流幅度，该值是 "i"。确定电容 C，使用为i的值 ，用等式1中，对于正常化到电极面积（占表面粗糙度如果合适）在μFcm -2并且报价。高品质的"金属般的"BDD的电容&lt;&lt; 10μF厘米-2。使用绘图软件介绍和分析数据的任何数据。 I = C（Vt的-1）（1当量）; 其中 ，i是电流（A）和（V 吨 -1）是电势扫描速率。 </li></ol></li><li>溶剂窗口<ol><li>清洗电极如步骤4.2.1。使用电位为0.1V秒运行0.1M的KNO 3简历-1 0 V至-2 V，那么之间-2 V和+ 2V一个次回到0 V配合BDD作为工作电极相对于一个共同的参比电极和Pt对电极。重复。分析第二个CV，CV 示于图2B的一个例子。 </li><li>将电流转换为电流密度（mA厘米-2），取表面粗糙度考虑在内，及注明溶剂窗口由±0.4毫安厘米的电流限值-2在两个方向上所限定的电势窗。7,29使用绘图软件的任何数据介绍和分析数据。 </li><li>观察NDC（SP 2碳）在溶剂窗口的证据;氧还原反应是有利的NDC，这显然是显而易见的，在还原性窗口。藻含有2基团的氧化还导致特征峰只是水的电解在阳极窗口（图2B）之前。 注:高品质的"金属"BDD电极具有溶剂窗&gt;&gt; 3 V，不支持的氧还原REAC灰（ORR）在0.1M KNO 3（或 ORR强烈动力学延迟），并显示可忽略不计的NDC氧化签名。 </li></ol></li><li>氧化还原电化学<ol><li>清洗电极如步骤4.2.1。 </li><li>使用1毫米的钌六胺恒电位仪记录的个人简历（茹（NH 3）6 3+）和0.1M的KNO 3之间 +0.2 V和-0.8 V与SCE，用于扫描速率范围为0.05 V为秒 -1 - 0.2 V 秒 -1。 注:这对夫妻显示快速的电子转移，是电在挑战p型半导体BDD的区域。藻含有2 BDD也将在该区域显示的ORR，为后者的信号更明显，因为茹（NH 3）的6 3+降低的浓度。 </li><li>测量阳极和从记录的CV还原峰电流（Δëp）和温度如所述20之间的电压隔离。对于"金属般的"欧姆接触氧终止BDD在298 K，ΔêP &lt;70毫伏30,31。较大的ΔË 的p值是根据症状的不良欧姆接触或低级硼含量，以3×10 20乙原子厘米如图 2C所示为掺杂物密度的范围为9.2×10 16的BDD电极-3。 </li><li>测量前向扫描的峰值电流，I P， 并与从兰德尔斯Sevcik方程2 3,30（在298K引述）预期关联，假设电极是盘形几何和足够大（直径1毫米），该线性扩散支配。使用绘图软件介绍和分析数据的任何数据。 I P = 2.69×10 5 N 3/2 公元 1/2 CV 1/2（EQ 2） 其中 n是转移的电子数目，A是面积（cm 2），D为扩散系数（厘米2 秒 -1），c是浓度（mol cm -3）的和v是扫描速率（V 秒 -1）。 </li></ol></li></ol> 5. pH值代:pH敏感电极和pH产生的制备<ol><li>氧化铱（pH敏感）溶液的制备<ol><li>准备20ml的0.1M的KNO 3溶液中第5.4.1节。加入5滴的使用巴氏吸管和搅拌酚酞指示液（这是足以看到由眼的响应，但对于一个更强烈的颜色，添加更多滴）。放置在溶液中的BDD工作电极和Pt对电极。 </li><li>调节溶液的pH至10.5，加入无水氯化钾盐，连续搅拌。离开覆盖并搅拌48小时，在室温，以稳定，在此阶段溶液会逐渐从黄绿色到去蓝紫色。存放在冰箱中，在3℃。 </li></ol></li><li> pH敏感氧化铱薄膜沉积<ol><li>使用恒电位0V和+ 1V与SCE之间运行中的氧化铱溶液简历确定在哪个最大电流被记录的潜力。这是沉积电势，E DEP 如图3A所示，通常介于〜+ 0.6V的卧- 0.85伏;它可以根据许多因素如温度，电极材料等 32，33变化</li><li>使用计时电流与稳压器，从0V（在软件"初始E"和"低E"），其中无电解（在软件"高E"）时发生到 E DEP步骤的潜力，为0.2的时间周期每步秒，重复100倍。 </li><li>在0 V和+ 1V 0.1 MH 2 SO 4的IrO x中沉积的电极运行的简历。人物信息研究所的CV形状示于图3B。的电流密度范围在〜0.6 mA的厘米-2 - 0.7 mA的cm -2的用于第一阳极峰（对应于为0.7 mA的厘米-2〜8纳米的平均膜厚度），表示一个稳定的pH敏感膜34， 35。 </li><li>如果电流密度小于0.6 mA的cm -2的重复步骤5.2.2 - 5.2.4直到达到该值。留在pH为7的缓冲溶液中的电极24小时以水合作为IrO x中膜的反应是水合依赖性33。 </li></ol></li><li>的IrO X片 pH值表征<ol><li>制备一系列缓冲溶液，其覆盖感兴趣的pH范围（pH值为2 - pH为12），这些都可以在房屋成为（例如卡莫迪36）或商购。 </li><li>用蒸馏水冲洗电极。放置在最低的pH的缓冲溶液中的IrO x中电极和参比电极。使用稳压器记录开路电势（OCP）在30秒内，用三个重复。从溶液，冲洗并置于下一个缓冲区中取出电极。 </li><li>为每个缓冲区重复步骤5.3.2，然后重复该系列的至少两倍。剧情pH值与OCP的校正曲线为影片的反应。一个IrO x中膜显示出与59之间的梯度的斜坡-每十年37 80毫伏。 注: 图3C显示了一个例子校准图上BDD成功IrO x中的pH传感器。 </li></ol></li><li>使用pH发生器和测量系统 注:此假设使用其中一个电极涂覆有IrO x中膜（如光盘）和第二（例如BDD环）的双电极系统将产生的 H +或OH -恒电流电解水。 <ol><li>通过添加去离子水到该盐制备20ml的0.1M的KNO 3溶液。连接IrO x中涂电极作为在两电极系统的工作电极，与第二电极稳定的参考电极如 SCE。使用稳压器，以建立初始pH值测量OCP。 </li><li>发电机电极连接到一个合适的双电极恒流系统有对电极， 例如Pt箔，并重复步骤5.4.1，但所界定的时间周期之后施加电流到发生器电极。 注:我们发现在0〜±50μA适合我们的BDD电极的电流;更大的电流造成明显的气体逸出。的电流的大小和方向取决于所期望的结果;一个正电流将导致转向更酸性的pH值，并更碱性pH的负电流时，电流越大就越大的pH变化。 </li><li>使用恒电位仪，记录OCP的变化响应恒电流下，等到反应稳定。然后把IrO x中</suB&gt;电极在PH7的缓冲液10分钟，以重新平衡的IrO x膜 。 </li><li>重复步骤5.4.2至5.4.3具有不同的施加的电流，直到所有需要的数据已经收集。积使用第5.3获得OCP转换至pH校正曲线的数据，例如一个数据集被示出在图4A中。从+2 V在0.1 MH 2 SO 4取出用氧化铝抛光或脉冲税务条例x膜为-2 V为0.2秒，×100。适用于所关注的测量系统。 </li></ol></li><li>局部pH产生视觉评估<ol><li>准备20ml的0.1M的KNO 3溶液中第5.4.1节。加入5滴的使用巴氏吸管和搅拌酚酞指示液（这是足以看到由眼的响应，但对于一个更强烈的颜色，添加更多滴）。放置在溶液中的BDD工作电极和Pt对电极。 </li><li>用施加负电流到工作电极一个恒电流如在步骤5.4.2（例如〜-0.6毫安厘米-2），使得该溶液改变从无色色为粉红色。这个现在本地产生的溶液是在pH≥10.5。 </li><li>与5滴甲基红溶液代替酚酞和搅拌重复步骤5.5.1。施加足够正电流（例如〜6.6 mA的厘米-2），使得该溶液颜色发生变化，从黄到红。这个现在本地产生的溶液是在pH 4.2≤38。 </li></ol></li></ol>

The authors declare that they have no competing financial interests.

带有O形端的表面开始提倡，因为氢终止表面是电化学不稳定的，尤其是在高的阳极电位7,40,41。改变表面终止可能影响范围内的夫妇，如电解水（这里用来改变当地溶液的pH值）的电子转移反应动力学。此外，如果包含的BDD显著NDC在晶界也有可能是在施加极端阳极的/阴极电位主张本文用于pH代，蚀刻可能发生在这些弱点。这将导致该膜腐蚀和薄膜，最终剥离，这表现在一种不稳定的PH值产?...

电极材料的选择是非常重要在进行任何电化学研究时。在最近几年，sp 3键碳（金刚石）掺杂有足够硼呈现材料"金属样"已成为广泛的电分析应用的流行的选择由于其优异的电化学（和热和机械）性能1,2- 3。这些包括极端的解决方案，温度和压力条件4超宽溶剂窗户，低背景电流下的耐腐蚀性，并降低了结垢，相较于其他常用的电极材料5-7,3。但是，增加的非金刚石碳（NDC:藻2）的含量会导致降低的窗口溶剂，增加背景电流7,8，改变在两个不同的朝向内球的氧化还原物质的结构完整性和灵敏度，例如。氧气9-12。 请注意这样我的应用程序，NDC的存在被认为是有利的13。此外，如果材料不含有足够的硼它将表现为p型半导体，并显示氧化还原物种中的还原电位窗口，其中该材料被最耗尽电荷载体7的敏感性降低。最后，掺硼金刚石的表面化学（BDD）也可以起到在所观察到的电化学应答的作用。这是内球物种是敏感的表面化学和降低掺杂金刚石，其中氢（H - ） -尤其如此终止的表面可以使半导电BDD电极出现"金属状"7。 要利用的BDD的优异性能，它往往是必要的材料被充分掺杂且包含尽可能少的NDC越好。依赖于通过中生长的BDD的方法中，属性可以变化14,15。本文首先提出了一种材料和选rochemical表征协议指导，以评估在使用前BDD电极适用性（ 即充足的硼，最小的NDC），然后描述了基于局部改变pH值电化学使用的协议验证电极一个应用程序。这个过程需要NDC - 自由的BDD朝在施加施加极端电位（或电流），用于长时间腐蚀或溶解的表面韧性的优点。特别是使用一个BDD电极，以产生稳定的质子（H +）或氢氧化物（OH - ）通量由于水在靠近第二（传感器）电解（分别氧化或还原）16,17在这里被描述。 以这种方式，可以控制传感器的pH值环境中以系统的方式，例如，用于pH滴定实验，或以固定pH值在一个值，其中该电化学过程是最敏感的。后者为特别有用应用中的传感器被放置在源， 如河流，湖泊，海洋和体系的pH不是最佳为感兴趣的电化学测量。两个最近的例子包括:（i）产生的局部低pH，在pH值为中性溶液，用于电沉积和汞17的汽提;注意BDD是金属电沉积青睐的材料，由于扩展阴极窗口9,18,19。 （二）的硫化氢，本在高pH值，所述电化学检测形式的定量通过从中立到强碱性16局部增加的pH值。

<table><tbody><tr><td>Pt Wire</td><td></td><td></td><td>Counter Electrode</td></tr><tr><td>Saturated Calomel Electrode</td><td>IJ Cambria Scientific Ltd.</td><td>2056</td><td>Reference Electrode (alternatively use Ag|AgCl)</td></tr><tr><td>BDD Electrode</td><td></td><td></td><td>Working Electrode</td></tr><tr><td>Iridium Tetrachloride</td><td>VWR International Ltd</td><td>12184.01</td><td></td></tr><tr><td>Hydrogen Peroxide</td><td>Sigma-Aldrich</td><td>H1009</td><td>(30% w/w) Corrosive</td></tr><tr><td>Oxalic Acid&amp;nbsp;</td><td>Sigma-Aldrich</td><td>241172</td><td>Harmful, Irritant</td></tr><tr><td>Anhydrous Potassium Chloride</td><td>Sigma-Aldrich</td><td>451029</td><td></td></tr><tr><td>Sulphuric Acid</td><td>VWR International Ltd</td><td>102765G</td><td>(98%) Corrosive</td></tr><tr><td>Potassium Nitrate</td><td>Sigma-Aldrich</td><td>221295</td><td></td></tr><tr><td>Hexaamine Ruthenium Chloride</td><td>Strem Chemicals Inc.</td><td>44-0620</td><td>Irritant</td></tr><tr><td>Perchloric Acid</td><td>Sigma-Aldrich</td><td>311421</td><td>Oxidising, Corrosive</td></tr><tr><td>2-Propanol</td><td>Sigma-Aldrich</td><td>24137</td><td>Flammable</td></tr><tr><td>Nitric Acid</td><td>Sigma-Aldrich</td><td>695033</td><td>Oxidising, Corrosive</td></tr><tr><td>Sputter/ Evapourator</td><td></td><td></td><td>With Ti &amp;amp; Au targets</td></tr><tr><td>Raman</td><td></td><td></td><td>514.5 nm laser</td></tr><tr><td>Annealing Oven</td><td></td><td></td><td>Capable of 400 &amp;deg;C</td></tr><tr><td>Ag paste</td><td>Sigma-Aldrich</td><td>735825</td><td>or other conductive paint</td></tr><tr><td>Potentiostat</td><td></td><td></td><td></td></tr><tr><td>pH Buffer solutions</td><td>Sigma-Aldrich</td><td>38740-38752</td><td>Fixanal buffer concentrates</td></tr><tr><td>Phenolphthalein Indicator</td><td>VWR International Ltd</td><td>210893Q</td><td></td></tr><tr><td>Methyl Red Indicator</td><td>Sigma-Aldrich</td><td>32654</td><td></td></tr></tbody></table>

assessment of boron doped diamond electrode quality and application to in situ modification of local ph by water electrolysis

硼掺杂的金刚石（BDD）的电极已经显示相当大的希望作为其中他们的许多报告性质如延长溶剂窗口，低背景电流，耐腐蚀等 ，从表面的催化惰性性质出现的电极材料。但是，如果在生长过程中，非金刚石碳（NDC）变得掺入到电极矩阵，电化学性能将随着表面变得更具有催化活性。因此，它是重要的electrochemist意识到的质量和所得到的在使用前的BDD电极的键电化学性能。本文介绍了一系列表征步骤，包括拉曼显微镜，电容，溶剂的窗口和氧化还原电化学，以确定BDD电极是否包含NDC可以忽略不计，即可以忽略不计的SP 2的碳。一个应用是强调了采取的催化惰性优势和NDC-自由表面的耐腐蚀的性质，即稳定的，可量化的地方质子和氢氧化生产，由于电解水在BDD电极。测量使用铱氧化物涂覆的BDD电极通过水电解诱导局部pH变化的方法进行详细描述的。

用于与不同的掺杂密度代表的BDD macrodisc电极获得拉曼光谱和电化学特性，并且两个显著和可以忽略的程度的NDC的，图1和2。 图1A和 B示出典型的拉曼数据为NDC-含有薄膜微晶BDD和较大的晶粒独立BDD，掺杂上述金属门​​限，分别为。 NDC的存在是可识别由之间1400 1600 -1标记的宽峰;不存在这样的峰在图1C，...

Watch this Scientific Journal Video about Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis at JoVE.com

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

甲协议在原位 pH值代实验描述了硼掺杂的金刚石（BDD）电极和随后的应用程序的关键电化学参数的表征。

掺硼金刚石电极质量和应用，以评估<em&gt;原位</em&gt;本地pH值通过水电改造

Boron doped diamond (BDD) electrodes have shown considerable promise as an electrode material where many of their reported properties such as extended ...

assessment-boron-doped-diamond-electrode-quality-application-to-situ

Research

JoVE Journal

Chemistry

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

14.7K 次观看.  University of Warwick. 甲协议在原位 pH值代实验描述了硼掺杂的金刚石（BDD）电极和随后的应用程序的关键电化学参数的表征。 

视频: Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

Electrochemically and Bioelectrochemically Induced Ammonium Recovery

Streams such as urine and manure can contain high levels of ammonium, which could be recovered for reuse in agriculture or chemistry. The extraction of ammonium from an ammonium-rich stream is demonstrated using an electrochemical and a bioelectrochemical system. Both systems are controlled by a potentiostat to either fix the current (for the electrochemical cell) or fix the potential of the working electrode (for the bioelectrochemical cell). In the bioelectrochemical cell, electroactive bacteria catalyze the anodic reaction, whereas in the electrochemical cell the potentiostat applies a higher voltage to produce a current. The current and consequent restoration of the charge balance across the cell allow the transport of cations, such as ammonium, across a cation exchange membrane from the anolyte to the catholyte. The high pH of the catholyte leads to formation of ammonia, which can be stripped from the medium and captured in an acid solution, thus enabling the recovery of a valuable nutrient. The flux of ammonium across the membrane is characterized at different anolyte ammonium concentrations and currents for both the abiotic and biotic reactor systems. Both systems are compared based on current and removal efficiencies for ammonium, as well as the energy input required to drive ammonium transfer across the cation exchange membrane. Finally, a comparative analysis considering key aspects such as reliability, electrode cost, and rate is made.
This video article and protocol provide the necessary information to conduct electrochemical and bioelectrochemical ammonia recovery experiments. The reactor setup for the two cases is explained, as well as the reactor operation. We elaborate on data analysis for both reactor types and on the advantages and disadvantages of bioelectrochemical and electrochemical systems.

We demonstrate the extraction of ammonium from an ammonium-rich stream using an electrochemical and a bioelectrochemical system. The reactor setup, operation and data analysis are discussed.

电化学和Bioelectrochemically诱导铵恢复

Streams such as urine and manure can contain high levels of ammonium, which could be recovered for reuse in agriculture or chemistry. The extraction of ...

科研

化学

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (&#181;PAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

The study demonstrates the growth of iridium oxide-reduced graphene oxide (IrO2-RGO) nanohybrid thin films on irregular and rough screen-printed carbon substrate through a green electrochemical synthesis, and their implementation as a pH sensor with a patterned paper-fluidic platform.

氧化铱还原氧化石墨烯纳米杂化薄膜修饰丝网印刷电极一次性电化学微流控纸pH传感器

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use ...

工程学

Self-standing Electrochemical Set-up to Enrich Anode-respiring Bacteria On-site

Anaerobic respiration coupled with electron transport to insoluble minerals (referred to as extracellular electron transport [EET]) is thought to be critical for microbial energy production and persistence in many subsurface environments, especially those lacking soluble terminal electron acceptors. While EET-capable microbes have been successfully isolated from various environments, the diversity of bacteria capable of EET is still poorly understood, especially in difficult-to-sample, low energy or extreme environments, such as many subsurface ecosystems. Here, we describe an on-site electrochemical system to enrich EET-capable bacteria using an anode as a respiratory terminal electron acceptor. This anode is connected&#160;to a cathode capable of&#160;catalyzing abiotic oxygen reduction. Comparing this approach with electrocultivation methods that use a potentiostat for poising the electrode potential, the two-electrode system does not require an external power source. We present an example of our on-site enrichment utilized in an alkaline pond at the Cedars, a terrestrial serpentinization site in Northern California. Prior attempts to cultivate mineral reducing bacteria were unsuccessful, which is likely due to the low-biomass nature of this site and/or the low relative abundance of metal reducing microbes. Prior to implementing our two-electrode enrichment, we measured the vertical profile of dissolved oxygen concentration. This allowed us to place the carbon felt anode and platinum-electroplated carbon felt cathode at depths that would support anaerobic and aerobic processes, respectively. Following on-site incubation, we further enriched the anodic electrode in the laboratory and confirmed&#160;a distinct microbial community compared to the surface-attached or biofilm communities normally observed at the Cedars. This enrichment subsequently led to the isolation of the first electrogenic microbe from the Cedars. This method of on-site microbial enrichment has the potential to greatly enhance the isolation of EET-capable bacteria from low biomass or difficult to sample habitats.

On-site microbial enrichment or in situ cultivation techniques can facilitate the isolation of difficult-to-culture microbial taxa, especially from low-biomass or geochemically extreme environments. Here, we describe an electrochemical set-up without using an external power source to enrich microbial strains that are capable of extracellular electron transport (EET).

自立电化学建立富集阳极 respiring 菌现场

Anaerobic respiration coupled with electron transport to insoluble minerals (referred to as extracellular electron transport [EET]) is thought to be ...

环境科学

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO2/LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope.

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

A protocol for the fabrication of electrochemically active LiPON-based solid-state lithium-ion nanobatteries using a focused ion beam is presented.

基于 LiPON 的固态锂离子 Nanobatteries 的聚焦离子束制备方法在原位测试中的研究

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of ...

In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate multiple processes responsible for long-term performance decay. Given the complexity of physical processes occurring inside the cell, it is often challenging to achieve a full understanding of the root causes of this performance degradation. This difficulty arises in part from the fact that any electrochemical measurement of a battery will return the combined contributions of all components in the cell. Incorporation of a reference electrode can solve part of the problem, as it allows the electrochemical reactions of the cathode and the anode to be individually probed. A variation in the voltage range experienced by the cathode, for example, can indicate alterations in the pool of cyclable lithium ions in the full-cell. The structural evolution of the many interphases existing in the battery can also be monitored, by measuring the contributions of each electrode to the overall cell impedance. Such wealth of information amplifies the reach of diagnostic analysis in Li-ion batteries and provides valuable input to the optimization of individual cell components. In this work, we introduce the design of a test cell able to accommodate multiple reference electrodes, and present reference electrodes that are appropriate for each specific type of measurement, detailing the assembly process in order to maximize the accuracy of the experimental results.

The incorporation of reference electrodes in a Li-ion battery provides valuable information to elucidate degradation mechanisms at high voltages. In this article, we present a cell design that accommodates multiple reference electrodes, along with the assembly steps to assure maximum accuracy of the data obtained in electrochemical measurements.

原位锂化参考电极: 四原位阻抗谱的电极设计

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate ...

Electrochemical Roughening of Thin-Film Platinum Macro and Microelectrodes

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries of the metal. Using this method, a crack free, thin-film macroelectrode surface with up to 40 times increase in active surface area was obtained. The roughening is easy to do in a standard electrochemical characterization laboratory and incudes the application of voltage pulses followed by extended application of a reductive voltage in a perchloric acid solution. The protocol includes the chemical and electrochemical preparation of both a macroscale (1.2 mm diameter) and microscale (20 &#181;m diameter) platinum disc electrode surface, roughening the electrode surface and characterizing the effects of surface roughening on electrode active surface area. This electrochemical characterization includes cyclic voltammetry and impedance spectroscopy and is demonstrated for both the macroelectrodes and the microelectrodes. Roughening increases electrode active surface area, decreases electrode impedance, increases platinum charge injection limits to those of titanium nitride electrodes of same geometry and improves substrates for adhesion of electrochemically deposited films.

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries. The electrochemical techniques of cyclic voltammetry and impedance spectroscopy are demonstrated to characterize these electrode surfaces.

薄膜铂金宏观和微电极的电化学粗加工

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries ...

Electrochemical Preparation of Poly(3,4-Ethylenedioxythiophene) Layers on Gold Microelectrodes for Uric Acid-Sensing Applications

Two different methods for the synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on gold electrodes are described, using electropolymerization of 3,4-ethylenedioxythiophene (EDOT) monomer in an aqueous and an organic solution. Cyclic voltammetry (CV) was used in the synthesis of PEDOT thin layers. Lithium perchlorate (LiClO4) was used as a dopant in both aqueous (aqueous/acetonitrile (ACN)) and organic (propylene carbonate (PC)) solvent systems. After the PEDOT layer was created in the organic system, the electrode surface was acclimatized by successive cycling in an aqueous solution for use as a sensor for aqueous samples. 
The use of an aqueous-based electropolymerization method has the potential benefit of removing the acclimatization step to have a shorter sensor preparation time. Although the aqueous method is more economical and environmentally friendly than the organic solvent method, superior PEDOT formation is obtained in the organic solution. The resulting PEDOT electrode surfaces were characterized by scanning electron microscopy (SEM), which showed the constant growth of PEDOT during electropolymerization from the organic PC solution, with rapid fractal-type growth on gold (Au) microelectrodes.

Electrochemical Preparation of Poly3,4-Ethylenedioxythiophene Layers on Gold Microelectrodes for Uric Acid-Sensing Applications

We describe aqueous and organic solvent systems for the electropolymerization of poly(3,4-ethylenedioxythiophene) to create thin layers on the surface of gold microelectrodes, which are used for sensing low molecular weight analytes.

在金微电极上电化学制备聚（3，4-乙烯二氧噻吩）层在尿酸传感应用中

Two different methods for the synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on gold electrodes are described, using electropolymerization of ...

Manufacturing of a Nafion-coated, Reduced Graphene Oxide/Polyaniline Chemiresistive Sensor to Monitor pH in Real-time During Microbial Fermentation

Here, we report the engineering of a solid-state micro pH sensor based on polyaniline-functionalized, electrochemically reduced graphene oxide (ERGO-PA). Electrochemically reduced graphene oxide acts as the conducting layer and polyaniline acts as a pH-sensitive layer. The pH-dependent conductivity of polyaniline occurs by doping of holes during protonation and by the dedoping of holes during deprotonation. We found that an ERGO-PA solid-state electrode was not functional as such in fermentation processes. The electrochemically active species that the bacteria produce during the fermentation process interfere with the electrode response. We successfully applied Nafion as a proton-conducting layer over ERGO-PA. The Nafion-coated electrodes (ERGO-PA-NA) show a good sensitivity of 1.71 &#937;/pH (pH 4 - 9) for chemiresistive sensor measurements. We tested the ERGO-PA-NA electrode in real-time in the fermentation of Lactococcus lactis. During the growth of L. lactis, the pH of the medium changed from pH 7.2 to pH 4.8 and the resistance of the ERGO-PA-NA solid-state electrode changed from 294.5 &#937; to 288.6 &#937; (5.9 &#937; per 2.4 pH unit). The pH response of the ERGO-PA-NA electrode compared with the response of a conventional glass-based pH electrode shows that reference-less solid-state microsensor arrays operate successfully in a microbiological fermentation.

Here, we report the protocol for the fabrication of a Nafion-coated, polyaniline-functionalized, electrochemically reduced graphene oxide chemiresistive micro pH sensor. This chemiresistor-based, solid-state micro pH sensor can detect pH changes in real-time during a Lactococcus lactis fermentation process.

在微生物发酵过程中制造一种纳菲安涂层、还原石墨烯 Oxide/Polyaniline 化学电阻传感器, 以实时监测 ph 值

Here, we report the engineering of a solid-state micro pH sensor based on polyaniline-functionalized, electrochemically reduced graphene oxide (ERGO-PA). ...

生物工程

<meta charset="utf8"></head><body>DHNA 对 植物乳植杆菌 EET 进行计时安培分析

Characterizing Mediated Extracellular Electron Transfer in Lactic Acid Bacteria with a Three-Electrode, Two-Chamber Bioelectrochemical System

Many bacteria perform extracellular electron transfer (EET), whereby electrons are transferred from the cell to an extracellular terminal electron acceptor. This electron acceptor can be an electrode and electrons can be delivered indirectly via a redox-active mediator molecule. Here, we present a protocol to study mediated EET in Lactiplantibacillus plantarum, a probiotic lactic acid bacterium widely used in the food industry, using a bioelectrochemical system. We detail how to assemble a three-electrode, two-chambered bioelectrochemical system and provide guidance on characterizing EET in the presence of a soluble mediator using chronoamperometry and cyclic voltammetry techniques. We use representative data from 1,4-dihydroxy-2-naphthoic acid (DHNA)-mediated EET experiments with L. plantarum to demonstrate data analysis and interpretation. The techniques described in this protocol can open new opportunities for electro-fermentation and bioelectrocatalysis. Recent applications of this electrochemical technique with L. plantarum demonstrated an acceleration of metabolic flux towards producing fermentation end-products, which are critical flavor components in food fermentation. As such, this system has the potential to be further developed to alter flavors in food production or produce valuable chemicals.

<meta charset="utf8"></head><body>用三电极、两室生物电化学系统表征乳酸菌介导的细胞外电子转移

Here we present a protocol for characterizing mediated extracellular electron transfer (EET) in lactic acid bacteria using a three-electrode, two-chamber bioelectrochemical system. We illustrate this method with Lactiplantibacillus plantarum and the redox mediator 1,4-dihydroxy-2-naphthoic acid and provide a thorough description of the electrochemical techniques used to evaluate mediated EET.

掺硼金刚石电极质量和应用，以评估

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