Name: simple methods for the preparation of non-noble metal bulk-electrodes for electrocatalytic applications
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我们感谢B. Konkena und W. Schuhmann进行有价值的科学讨论。化学工业（Liebig授予U.-PA）和Deutsche Forschungsgemeinschaft（Emmy Noether授予U-PA，AP242 / 2-1）的财务支持。

1.高温合成Fe 4.5 Ni 4.5 S 8 注意:本文所述的合成Fe 4.5 Ni 4.5 S 8的方法从文献中采用。 8,10所报告的加热斜坡的严格应用对于防止相位杂质的形成和二氧化硅安瓿的缺陷是非常重要的。 <ol><li>在研钵中充分混合铁（1.66g，29.8mmol），镍（1.75g，29.8mmol）和硫（1.70g，53.1mmol），并将混合物转移到二氧化硅安瓿（直径10mm）。 </li><li>以10 -2 mbar将安瓿蒸发过夜。 </li><li>密封安瓿并将其放入管式炉中。 </li><li>以5℃/ min将温度从室温（RT）升至700℃，然后进行等温步骤3小时。 </li><li>在30分钟内将温度升高至1100℃，k将其等温10小时。 </li><li>关闭炉子，慢慢将样品冷却至室温。破解安瓿收集固体产品。确保将Fe 4.5 Ni 4.5 S 8与石英玻璃碎片完全分离。 </li></ol>物理特征<ol><li>在样品架上安装一个10 mm x 5 mm x 3 mm的Fe 4.5 Ni 4.5 S 8岩石块，放在SEM仪器的真空室中。记录SEM图像为650X和6500X放大倍数为20kV。同时，使用相同的样品进行4.4 kV的EDX分析。 </li><li>为了收集PXRD数据，应用Fe 4.5 Ni 4.5 S 8的细磨粉末，并使用硅油将其安装在非晶硅晶片上。将晶片安装在样品架上，并使用Cu-Kα辐射（λ= 1.5418Å）以0.03°/ s的扫描速率从10-50°以连续扫描模式收集数据。 </l我&gt; <li>对于Mössbauer分析，使用细磨粉末并置于聚甲醛（POM）杯中。在25°C下使用Rh-Matrix中的57 Co辐射源记录零场Mössbauer光谱。 </li><li>对于DSC分析，将细磨粉末放置在去皮α-Al 2 O 3坩埚中。在RT至1000°C的范围内进行DSC测量，以10℃/ min的速率记录加热和冷却曲线。在高纯度氮气流下进行实验。 </li></ol> 3.制备"岩石"电极<ol><li>将铜线焊接到电线套圈上。 </li><li>将Fe 4.5 Ni 4.5 S 8块体材料切成更小的片（约5 mm x 5 mm x 5 mm）。 </li><li>将小的Fe 4.5 Ni 4.5 S 8放在套圈中， 2mm的材料从套圈中伸出。 </li><li>套管和铜线套管100毫米特氟龙管。 </li><li>用双组分环氧胶密封电极的尖端，并在环境条件下将电极干燥过夜。 </li><li>研磨尖端，直到暴露出Fe 4.5 Ni 4.5 S 8的光泽表面（金属光洁度）。用精细砂纸（20,14,3和1μm砂砾）进一步抛光以获得光滑的表面。 </li><li>用去离子水清洁表面，让其在空气中干燥。 </li></ol> 4.制备"粒状"电极注意:使用带有黄铜棒的定制特氟龙肠衣作为"丸粒"电极（直径3mm）的接触。 <ol><li>研磨50mg材料，得到Fe 4.5 Ni 4.5 S 8材料的细粉末。 </li><li>将细磨的粉末填充到压缩工具（直径3毫米）中，并以最大重量为800公斤/厘米2的压力按压材料。 </li><li>取出宝石从模具中使用距离支架。 </li><li>在聚四氟乙烯套管的空腔中的黄铜棒上涂上双组分银环氧胶。避免对特氟龙套管尖端造成任何污染。 </li><li>将颗粒放在特氟龙套管中。颗粒的平面必须伸出〜1 mm。 </li><li>用纸巾清除特氟龙套管上的任何污染物。 </li><li>用电压表验证黄铜线和Fe 4.5 Ni 4.5 S 8颗粒之间的接触，以确保电导率。 </li><li>在60℃下固化双组分胶水12小时后，将电极冷却至环境温度。 </li><li>用砂纸（20,14,3和1μm砂砾）抛光电极，以在特氟隆表壳内获得光泽齐平的平坦表面。 </li><li>用去离子水清洁表面，并使其在环境条件下干燥。 </li></ol> 5.电极电化学测试注意:实验使用Fe 4.5 Ni 4.5 S 8电极作为工作电极，Ag / AgCl（饱和KCl或3 M KCl溶液）电极作为参比电极，Pt线或Pt栅格作为对电极，用标准的三电极设置完成了。装有搅拌棒的气密电池填充有用于所有电化学实验的由0.5MH 2 SO 4组成的电解质。在电极的电化学测试期间电解质不被更换。所有电位参考E RHE （RHE =可逆氢电极），根据E RHE = E Ag / AgCl + X + 0.059 pH，X = 0.197 V（饱和KCl）或X = 0.210 V（3 M KCl），除非另有说明除此以外。 <ol><li> 初步步骤 <ol><li>用恒电位仪的电线连接所有三个电极。 </li><li>向电化学电池中加入25 mL电解质（0.5 MH 2 SO 4 ）并调整电极以确保电极完全浸入溶液中。随后，打开恒电位仪。 </li><li>开启磁力搅拌。 </li></ol></li><li> 电极表面电化学清洗 <ol><li>进行循环伏安法（CV）实验，以获得可观察到的电化学过程的快速概述。 </li><li>将电位范围设置为0.2至-0.2 V，扫描速率为100 mV / s（非催化电势区）。此外，将周期数设置为20。 </li><li>开始循环过程，并等到上一个循环完成。如果至少最后3〜4次获得的循环重合，则完成电化学电极清洗。在发散的情况下，添加更多的循环，直到获得稳定的曲线。 </li></ol></li><li> 催化性能的测量 - 线性扫描伏安法 <ol><li>在开始实验之前，确定i R补偿值f或电化学设置。 </li><li>选择用于线性扫描伏安法（LSV）实验的程序，并将电位范围设置为0.2至-0.6 V，扫描速率设置为5 mV / s，包括实验中的i R值。开始实验</li><li>重复线性扫描实验以确保重复性。如果不可重复的结果从步骤5.2开始。 </li></ol></li><li> 稳定性测量和量化 <ol><li>执行受控电位库仑实验（CPC）。 </li><li>将电位设置为-0.6 V，实验时间至少为20 h（72,000 s）。 </li><li>同时通过气密的注射器从密封细胞的顶部空间通过隔膜每隔一小时收集气体样品至少4小时的实验。将样品注入GC仪器进行定量，并使用本仪器上记录的校准曲线确定产生的氢气量。 </li></ol></li><li&gt; 电化学表面积的估计（ESCA） 注意:本实验期间不要搅拌电解质溶液。 <ol><li>确定i R补偿以测量溶液的电阻。 </li><li>在循环伏安法实验中选择0.1和0 V之间的电位范围，并将扫描速率设置为10 mV s -1 。使用i R drop校正。将实验的周期数设置为5。 </li><li>重复步骤5.4.1）至5.4.2）扫描速率为20,30,40,50和60 mV s -1 。 </li><li>从获得的CV曲线中选出第五个循环进一步解释。 </li><li>确定充电电流密度差（Δj= j a j c ）并绘制这些值作为扫描速率的函数。线性斜率等于双电层电容C dl的两倍，这与电化学表面积（ECSA）成比例。 </li></ol></li><li> 萨尔瓦多电化学阻抗谱（EIS） <ol><li>在相应的开路电位和0.3V的超电势下，在50 kHz至1 Hz的频率范围内记录电化学阻抗谱。 </li><li>从收到的数据中绘制奈奎斯特图，以确定电荷转移电阻。 </li></ol></li></ol>

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作者没有什么可以披露的。

在真空密封的安瓿中进行Fe 4.5 Ni 4.5 S 8的合成，以防止在合成过程中材料的氧化。在合成过程中，温度控制是获得纯产品的关键。第一，非常缓慢的加热步骤从而防止硫的过热，这可能由于高硫压而导致安瓿的破裂。更重要的是通过缓慢加热样品来防止相位杂质如单硫化物固溶体（mss）。在700°C的后续退火步骤确保了系统的平衡。随后，在1100℃退火，最终导致形成一个纯的，与铁硫化镍相比较的高温相。 13 当准备"岩石"电极时，重要的是，一块"岩石"从套圈中伸出大约。 2毫米能够切割足够的材料到obta在平坦的电极表面（A = 0.135cm 2 ），而不暴露套圈。环氧胶用于固定套圈中的"岩石"以及固定特氟龙管，防止电解液与电极的任何部分之间的接触除了活性物质外。否则副反应可能发生，重复性受到阻碍。环氧树脂胶的应用应该是以胶水中没有气泡的方式进行的。这些气泡可能会导致套圈或材料的不必要的暴露。环氧树脂胶应至少干燥过夜以使其完全可加工。在"颗粒"电极的情况下，Teflon套管起到与前述"岩石"电极类似的作用。该 使用的催化剂应是具有良好导电性的良好的延性材料。否则，材料不能被压制，因此必须加入导电粘合剂材料以提供稳定性和导电性。间隙尺寸外壳与颗粒之间必须可忽略不计。因此，制备比特氟龙套管略大的丸粒更好。去除过量的银环氧胶也是重要的，以避免在电化学测量期间银的反应。在60℃下固化胶合电极后，建议在进一步制备之前将电极冷却至室温，否则压缩材料可能会破裂。为了获得明确的几何表面积（A = 0.071cm 2 ），没有任何裂缝和凹痕，颗粒必须伸出至少1毫米。它必须抛光，直到与表壳齐平。由于颗粒可能非常脆弱，所以使用墙面强度至少为2mm的特氟隆外壳可能会有所帮助，因此在研磨和抛光时可提供足够的支撑。为了提供一致的质量和表面的一致性，从最粗糙的角度开始，最终得到最好的磨蚀是合理的即通常，对于本文所述的体电极，必须注意，导电催化剂材料是强制性的，以确保快速的电子转移并防止电阻率的限制。将非导电催化剂材料实施到该电极型中的方法可以通过将催化剂固定在导电基材（ 例如炭黑，石墨）上并从该复合粉末开始制备电极来实现。然而，这种方法将排除准备"岩石"电极的可能性。使用与"颗粒"电极类似的方法获得高质量，特别是更多工业相关电极的另一步骤是将材料直接压在集电器（ 例如 Ni网）上，并且在将来的工作中将被我们探索。 在测试电催化性能之前抛光电极对获得可重复的结果至关重要。电子电极的洗净使电极平衡并从电极表面除去任何吸附的杂质。记录多个LSV以确保数据的重复性。与通常报道的稳定性测试（通常以相当低的电流密度（大多为10mA / cm 2 ））的恒电流方式进行比较，我们选择在高电势下进行恒电位稳定性测试，这导致高电流密度（ &gt; 500mA / cm 2 ）。这种应力测试的优点是将材料推到其电化学和机械极限以及提供更实际的电极测试。为了量化，电化学电池和注射器的气密性对于获得一致的结果是至关重要的。此外，GC的良好校准是强制性的。在该实验期间搅拌提供了电解质的充分混合并且促进氢气泡从电极上的解吸附CE。然而，在ECSA实验期间必须关闭搅拌，因为需要电化学双层层的正确堆积。从ESCA中可以得到与ESCA成正比的物质活动依赖性及其活性位点数的结论。因此，ECSA分析是一个简单的工具，可以比较不同催化剂的性能。 总而言之，我们合成了高导电性过渡金属硫化物Fe 4.5 Ni 4.5 S 8 ，并使用这种材料制备了两种类型的体电极。使用标准电化学方法（如LSV，CPC和ECSA测定）测试电极的析氢反应。使用GC测定氢析出速率，并且是在低过电位下的非贵金属催化剂中观察到的最高值。两种类型的电极的性能与"颗粒"电极稍微相似特别是电极活化。然而，这可能来源于"岩石"电极中过高估计的表面积。值得注意的是，"颗粒"电极具有可以更容易且更准确地确定和再现表面积的优点。这种特征使"颗粒"电极对于可比较的研究更有价值，而"岩石"电极更容易制备成本更低。未来的工作将重点放在设计"鳞片"电极的大规模版本。

波动的可再生能源如太阳能和风能的储存由于化石燃料逐渐褪色和随后的替代能源需求而具有重大的社会利益。在这方面，由于清洁的燃烧过程，氢气是分子能量储存解决方案的有希望的可持续候选者。 1此外，氢气可用作燃料或用作更复杂燃料（ 如甲醇）的起始原料。使用碳中和资源轻松合成氢的首选方法是使用可持续能量进行电化学还原水。 目前，已知铂及其合金是显示低过电位，快速反应速率和高电流密度下的操作的析氢反应（HER）的最有效的电催化剂。 2然而，由于其高价格和低自然丰度，需要非金属催化剂。在大量替代的非贵重过渡金属催化剂中， 3种特别是过渡金属二硫属元素（MX 2 ; M =金属; X = S，Se）已被证明具有高的HER活性。 4，5，6，7在这方面，我们最近提出了Fe 4.5 Ni 4.5 S 8作为高度耐用和活跃的"岩石"HER电催化剂。这种天然丰富的材料在酸性条件下是稳定的，并且具有良好定义的催化活性表面的高固有电导率。 8 虽然已经报道了许多具有高HER活性的材料，但是电极制备通常伴随着多个问题， 例如重现性和令人满意的稳定性（&gt; 24小时）。 Additionally，由于本体上过渡金属基催化剂的固有导电性通常较高，所以电极制备需要纳米结构的催化剂以允许有效的电子转移。然后将这些催化剂转化成含有粘合剂如Nafion和催化剂的催化剂油墨。之后，墨水滴涂在惰性电极表面（ 如玻璃碳）上。虽然在低电流密度下相当稳定，但是在高电流密度下通常观察到催化剂在电极载体上的增加的接触电阻和平均粘附性。因此，需要更多的制备方法和电极材料是显而易见的。 该方案提出了使用散装材料的高耐用性和成本效益的电极的新型制备方法。这种电极的先决条件是低的本征材料电阻。 Fe 4.5 Ni 4.5 S 8填充此标准，可以通过密封硅胶安瓿中的简单高温合成从元件中获得。使用粉末X射线衍射（PXRD），差示扫描量热法（DSC），扫描电子显微镜（SEM）和能量色散X射线光谱（EDX），获得的材料的特征在于其结构，形态和组成。将合成的材料加工成两种类型的体电极，即"岩石"和"颗粒"电极。然后使用标准电化学测试和通过气相色谱（GC）进行的H 2定量来研究两种电极类型的性能。介绍了两种类型电极的性能与常用滴涂实验相比较。

<table><tbody><tr><td>Iron, powder</td><td>Sigma-Aldrich, http://www.sigmaaldrich.com</td><td>12310-500G-R</td><td></td></tr><tr><td>Nickel, powder</td><td>Sigma-Aldrich, http://www.sigmaaldrich.com</td><td>203904-25G</td><td>H: 351-372-317-412;&lt;br/&gt; P: 281-273-308-313-302+352</td></tr><tr><td>Sulfur, powder</td><td>Sigma-Aldrich, http://www.sigmaaldrich.com</td><td>13803-1KG-R</td><td>H: 315</td></tr><tr><td>Silver Epoxy Glue EC 151 L</td><td>Polytec PT, http://www.polytec-pt.de/de/</td><td>161010-1</td><td>-</td></tr><tr><td>Two Component Epoxy Glue Uhu Plus Endfest</td><td>Uhu, http://www.uhu.com</td><td>-</td><td>&amp;nbsp;H: 315-319-317-411;&lt;br/&gt; &amp;nbsp;P: 101-102-261-272-280-302+352-333+313-362-363-305+351+338-337+313</td></tr><tr><td>Sulfuric Acid &gt;95%</td><td>VWR, https://ru.vwr.com</td><td>231-639-5</td><td>H: 290-314;&lt;br/&gt; S: (1/2)-26-30-45</td></tr><tr><td>PTFE Tube</td><td>-</td><td>-</td><td>Prepare 8 cm long peaces</td></tr><tr><td>Iron Sleeves</td><td>-</td><td>-</td><td>Connect to the copper wire</td></tr><tr><td>Copper Wire</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Lapping Film 3&amp;micro;m, 215.9 mm x 279 mm</td><td>3M, http://3mpro.3mdeutschland.de</td><td>60-0700-0232-8</td><td>Polish with a small amount of water</td></tr><tr><td>Lapping Film 1&amp;micro;m, 215.9 mm x 279 mm</td><td>3M, http://3mpro.3mdeutschland.de</td><td>60-0700-0266-6</td><td>Polish with a small amount of water</td></tr><tr><td>Sand Paper 20 &amp;micro;m, SiC</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Sand Paper 14 &amp;micro;m, SiC</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Dremel Model 225</td><td>Dremel, https://www.dremeleurope.com</td><td>2615022565</td><td>Use grinding pulley wheel for cutting&amp;nbsp;</td></tr><tr><td>Hand Made Pellet Press</td><td>Hand Made</td><td>-</td><td>-</td></tr><tr><td>Stirring Plate</td><td>-</td><td>-</td><td>-</td></tr><tr><td>GAMRY Reference 600</td><td>GAMRY Instruments, https://www.gamry.com</td><td>-</td><td>-</td></tr><tr><td>Gero Furnace 30-3,000 &amp;deg;C</td><td>http://www.carbolite-gero.de</td><td>-</td><td>-</td></tr><tr><td>Quartz glass ampule</td><td>Hand Made</td><td>-</td><td>-</td></tr><tr><td>Vacuum pump</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Hydraulic press</td><td>-</td><td>-</td><td>-</td></tr></tbody></table>

simple methods for the preparation of non-noble metal bulk-electrodes for electrocatalytic applications

通过元素的高温合成，合成组成为Fe 4.5 Ni 4.5 S 8的岩石材料。材料的结构和组成通过粉末X射线衍射（PXRD），Mössbauer光谱（MB），扫描电子显微镜（SEM），差示扫描量热法（DSC）和能量色散X射线光谱（EDX）表征。介绍了两种制备五面体电极的方法。在第一种方法中，一片合成的五面体岩石通过电线套圈直接接触。第二种方法是使用固定在特氟龙套管中的细磨粉末压制的镍盐颗粒。两种电极在通过无添加剂方法制备时，与普通的滴涂方法相比，在电催化转化过程中显示出高的耐久性。我们在这里展示了这样的电极的惊人的性能来完成水电罗氏进化反应（HER），并提出了一种通过电化学和气相色谱法评估电催化性能的标准化方法。此外，我们在0.6V的超电势下通过恒电位法报告稳定性测试，以探索在工业相关条件下的电解期间电极的材料限制。

由于存在突出的（111），（311），（222），（331）和（511）反射，通过粉末X射线衍射实验证实具有Pentlandite结构的Fe 4.5 Ni 4.5 S 8的成功合成（ 图1a ）。然而，在反应期间适当的温度控制是获得相纯物质的关键。值得注意的是，当将混合物以较高的加热速率（例如20℃/分钟）加热到700℃时，已经观察到单硫化物固溶体（mss），这是普通的五元素材料的杂质。还示出了这种样品的示例性XRD图案（ 图1a ，红色）。相反，如果施加适当的加热速度为5℃/分钟，则如果不均匀消除，则可以显着降低mss的外观（ 图1a ，黑色）。莫斯堡Pectroscopy（ 图1b ）证实了Fe 4.5 Ni 4.5 S 8样品的pentlandite结构。该材料显示出两个不同的不同铁位，其异构位移分别为0.13（±0.02）和0.50（±0.02）mm / s，以及分别为0.12（±0.02）和0.13（±0.02）的四极耦合（ 图1b ）。这一观察结果与文献报道和显示两个不同铁位的结构性结果非常一致。 12另外，差示扫描量热法（DSC）（ 图1c ）显示了612°C和861°C两个主要相变，证明根据文献报道没有不希望的相。 13 <img alt="图1" class="xfigimg" src="/files/ftp_upload/56087/56087fig1.jpg" /> 图1:XRD和Mössbauer光谱。 （ a ）以5℃/分钟（黑色）和20℃/分钟（红色）的加热速率制备的样品的XRD图案。作为参考，显示了从单晶衍射数据模拟的Pentlandite图案（蓝色）。对应于mss的反射标有＃。 （ b ）Mössbauer光谱和（c）Fe 4.5 Ni 4.5 S 8的 DSC曲线。该图的部分内容从以前的Nat Comm出版刊物中转载。 8 <a href="http://ecsource.jove.com/files/ftp_upload/56087/56087fig1large.jpg" target="_blank">请点击此处查看此图的较大版本。</a> 抛光的Fe 4.5 Ni 4.5 S 8岩石和颗粒电极的SEM图像如图2a所示 。我们采用EDX分析来确定表面材料的元素组成。 EDX光谱如图2b所示。光谱中的碳峰产生于使用碳垫将样品安装在支架上。从EDX定量 - 如图2c所示，铁和镍之间的比例确定为1.06:1.00。假设铁和镍的总和为9，实际总和为Fe 4.64 Ni 4.36 S 8.11 。与理想公式Fe 4.5 Ni 4.5 S 8的偏差在误差范围内。该结果与在样品的XRD图中观察纯Pentlandite相一致。 <img alt="图2" class="xfigimg" src="/files/ftp_upload/56087/56087fig2.jpg" /> 图2:SEM和EDX分析。 （ a ）&#39;岩石&#39;和（ b ）&#39;颗粒&#39;电极的SEM显微照片。比例尺= 1μ米（ c ）EDX光谱和（ d ）"岩石"电极的组成分析。该图的部分内容从以前的Nat Comm出版刊物中转载。 8 <a href="http://ecsource.jove.com/files/ftp_upload/56087/56087fig2large.jpg" target="_blank">请点击此处查看此图的较大版本。</a> 对于对HER的电化学性能测试，首先使用切割的岩石和由细磨粉末压制的颗粒分别制备电极。 "岩石"和"颗粒"电极制备的关键步骤分别显示在图3a和3b中。标准测试程序首先涉及电极的抛光和电化学清洗。然后，记录线性扫描伏安图（LSV），然后进行稳定性测试，加上产品定量。最后，电化学ce区域（ESCA）。在图3c中 ，示出了两种类型的电极的LSV。从LSV来看，对于"岩石"和"颗粒"电极，在电流密度为10mA / cm 2时，对于HER的过电位估计分别为-280mV和-285mV对RHE。剥离的滴涂电极没有显示任何改善的电催化性能。因此，制备方法对性能的影响较小。忽略了滴涂过程，对于电极的长期稳定性，可以观察到类似的行为（ 图3d ），而"沉淀"显示出更快的活化行为，如我们之前报道的"Rock"Fe 4.5 Ni 4.5 S 8电极。激活完成后，两个电极都显示出可比较的电流密度。然而，如果滴涂电极暴露于对比在电化学条件下，产生的大量氢气导致催化剂从电极载体脱离，从而导致系统失活。 图3d （插图）显示根据使用"岩石"电极的电解时间产生的氢气量。可以观察到"颗粒"电极的可比氢量。从GC定量的线性拟合的斜率，确定2.14 mmol H 2 h -1 cm -2的氢气产生速率，据我们所知，只有铂（11 mmol H 2 h -1） cm -2 ）。 14为了确定ECSA，将充电电流密度差绘制为扫描速率的函数。得到的图形如图3e所示。从斜坡，只有边缘差异在ECSA，从而可以观察到e个这样的测量的误差范围内的活性位点数。因此，两种制备类型都具有类似性能的电极。在图3f中 ，示出了来自"岩石"电极的EIS数据的示例性奈奎斯特图。同样，"颗粒"电极显示相同的行为。该图显示了Fe 4.5 Ni 4.5 S 8体电极的非常低的电荷转移电阻（R ct =57.2Ω），这与材料的高固有电导率一致。 <img alt="图3" class="xfigimg" src="/files/ftp_upload/56087/56087fig3.jpg" /> 图3:电极制备和电化学分析。 "岩石"（ a ）和"颗粒"（ b ）的制备步骤为Fe 4.5 Ni 4.5 S 8型电极。凌特（ c ）在"岩石"（黑色），"颗粒"（红色）和滴涂（蓝色）电极的5mV s -1下扫描伏安图（ c ）。 （ d ）0.6瓦的"岩石"（黑色）和"颗粒"电极（红色）超过18小时。插图显示了使用"岩石"电极的电解前4小时的氢气产生。蓝线表示数据的线性拟合。 （ e ）充电电流密度差作为"岩石"（黑色）和"颗粒"电极（红色）的扫描速率的函数。线性斜率表示电化学表面积（ECSA）。 f）奈奎斯特图和"岩石"电极在HER超电势（η= 300mV）下的等效电路。该图的部分内容从以前的Nat Comm出版刊物中转载。 8 <a href="http://ecsource.jove.com/files/ftp_upload/56087/56087fig3large.jpg" target="_blank">请点击这里查看更大的版本</a>数字。

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Simple Methods for the Preparation of Non-noble Metal Bulk-electrodes for Electrocatalytic Applications

提出了使用大块材料Fe 4.5 Ni 4.5 S 8的电极的简便制备方法。该方法提供了常规电极制造的替代技术，并描述了非常规电极材料的先决条件，包括直接的电催化测试方法。

用于制备用于电催化应用的非贵金属体电极的简单方法

The rock material pentlandite with the composition Fe4.5Ni4.5S8 was synthesized via high temperature synthesis from the elements. The structure and ...

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11.4K 次观看.  Ruhr-University Bochum. 提出了使用大块材料Fe 4.5 Ni 4.5 S 8的电极的简便制备方法。该方法提供了常规电极制造的替代技术，并描述了非常规电极材料的先决条件，包括直接的电催化测试方法。 

视频: Simple Methods for the Preparation of Non-noble Metal Bulk-electrodes for Electrocatalytic Applications

On the Preparation and Testing of Fuel Cell Catalysts Using the Thin Film Rotating Disk Electrode Method

We present a step-by-step tutorial to prepare proton exchange membrane fuel cell (PEMFC) catalysts, consisting of Pt nanoparticles (NPs) supported on a high surface area carbon, and to test their performance in thin film rotating disk electrode (TF-RDE) measurements. The TF-RDE methodology is widely used for catalyst screening; nevertheless, the measured performance sometimes considerably differs among research groups. These uncertainties impede the advancement of new catalyst materials and, consequently, several authors discussed possible best practice methods and the importance of benchmarking.
The visual tutorial highlights possible pitfalls in the TF-RDE testing of Pt/C catalysts. A synthesis and testing protocol to assess standard Pt/C catalysts is introduced that can be used together with polycrystalline Pt disks as benchmark catalysts. In particular, this study highlights how the properties of the catalyst film on the glassy carbon (GC) electrode influence the measured performance in TF-RDE testing. To obtain thin, homogeneous catalyst films, not only the catalyst preparation, but also the ink deposition and drying procedures are essential. It is demonstrated that an adjustment of the ink&#39;s pH might be necessary, and how simple control measurements can be used to check film quality. Once reproducible TF-RDE measurements are obtained, determining the Pt loading on the catalyst support (expressed as Pt wt%) and the electrochemical surface area is necessary to normalize the determined reaction rates to either surface area or Pt mass. For the surface area determination, so-called CO stripping, or the determination of the hydrogen underpotential deposition (Hupd) charge, are standard. For the determination of the Pt loading, a straightforward and cheap procedure using digestion in aqua regia with subsequent conversion of Pt(IV) to Pt(II) and UV-vis measurements is introduced.

Preparing and testing Pt/C fuel cell catalysts is subject to continuous discussion in the scientific community with respect to reproducibility and best practice. With the presented work, we intend to present a step-by-step tutorial to make and test Pt/C catalysts, which can serve as benchmark for novel catalyst systems.

用薄膜旋转圆盘电极法制备和测试燃料电池催化剂的研究

We present a step-by-step tutorial to prepare proton exchange membrane fuel cell (PEMFC) catalysts, consisting of Pt nanoparticles (NPs) supported on a ...

科研

环境科学

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 ...

Synthesis and Performance Characterizations of Transition Metal Single Atom Catalyst for Electrochemical CO2 Reduction

This protocol presents both the synthesis method of the Ni single atom catalyst, and the electrochemical testing of its catalytic activity and selectivity in aqueous CO2 reduction. Different from traditional metal nanocrystals, the synthesis of metal single atoms involves a matrix material that can confine those single atoms and prevent them from aggregation. We report an electrospinning and thermal annealing method to prepare Ni single atoms dispersed and coordinated in a graphene shell, as active centers for CO2 reduction to CO. During the synthesis, N dopants play a critical role in generating graphene vacancies to trap Ni atoms. Aberration-corrected scanning transmission electron microscopy and three-dimensional atom probe tomography were employed to identify the single Ni atomic sites in graphene vacancies. Detailed setup of electrochemical CO2 reduction apparatus coupled with an on-line gas chromatography is also demonstrated. Compared to metallic Ni, Ni single atom catalyst exhibit dramatically improved CO2 reduction and suppressed H2 evolution side reaction.

Synthesis and Performance Characterizations of Transition Metal Single Atom Catalyst for Electrochemical CO2 Reduction

Here, we present a protocol for the synthesis and electrochemical testing of transition metal single atoms coordinated in graphene vacancies as active centers for selective carbon dioxide reduction to carbon monoxide in aqueous solutions.

电化学 CO2还原的过渡金属单原子催化剂的合成及性能表征

This protocol presents both the synthesis method of the Ni single atom catalyst, and the electrochemical testing of its catalytic activity and selectivity ...

化学

A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various precursor noble metal ions with reducing agents in a 1:1 (v/v) ratio results in the formation of metal gels within seconds to minutes compared to much longer synthesis times for other techniques such as sol-gel. Conducting the reduction step in a microcentrifuge tube or small volume conical tube facilitates a proposed nucleation, growth, densification, fusion, equilibration model for gel formation, with final gel geometry smaller than the initial reaction volume. This method takes advantage of the vigorous hydrogen gas evolution as a by-product of the reduction step, and as a consequence of reagent concentrations. The solvent accessible specific surface area is determined with both electrochemical impedance spectroscopy and cyclic voltammetry. After rinsing and freeze drying, the resulting aerogel structure is examined with scanning electron microscopy, X-ray diffractometry, and nitrogen gas adsorption. The synthesis method and characterization techniques result in a close correspondence of aerogel ligament sizes. This synthesis method for noble metal aerogels demonstrates that high specific surface area monoliths may be achieved with a rapid and direct reduction approach.

A rapid, direct solution-based reduction synthesis method to obtain Au, Pd, and Pt aerogels is presented.

直接溶液还原法快速合成金、钯、铂气凝胶的研究

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various ...

Three-electrode Coin Cell Preparation and Electrodeposition Analytics for Lithium-ion Batteries

As lithium-ion batteries find use in high energy and power applications, such as in electric and hybrid-electric vehicles, monitoring the degradation and subsequent safety issues becomes increasingly important. In a Li-ion cell setup, the voltage measurement across the positive and negative terminals inherently includes the effect of the cathode and anode which are coupled and sum to the total cell performance. Accordingly, the ability to monitor the degradation aspects associated with a specific electrode is extremely difficult because the electrodes are fundamentally coupled. A three-electrode setup can overcome this problem. By introducing a third (reference) electrode, the influence of each electrode can be decoupled, and the electrochemical properties can be measured independently. The reference electrode (RE) must have a stable potential that can then be calibrated against a known reference, for example, lithium metal. The three-electrode cell can be used to run electrochemical tests such as cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). Three-electrode cell EIS measurements can elucidate the contribution of individual electrode impedance to the full cell. In addition, monitoring the anode potential allows the detection of electrodeposition due to lithium plating, which can cause safety concerns. This is especially important for the fast charging of Li-ion batteries in electric vehicles. In order to monitor and characterize the safety and degradation aspects of an electrochemical cell, a three-electrode setup can prove invaluable. This paper aims to provide a guide to constructing a three-electrode coin cell setup using the 2032-coin cell architecture, which is easy to produce, reliable, and cost-effective.

Three-electrode cells are useful in studying the electrochemistry of lithium-ion batteries. Such an electrochemical setup allows the phenomena associated with the cathode and anode to be decoupled and examined independently. Here, we present a guide for construction and use of a three-electrode coin cell with emphasis on lithium plating analytics.

锂离子电池三电极硬币电池制备及电沉积分析

As lithium-ion batteries find use in high energy and power applications, such as in electric and hybrid-electric vehicles, monitoring the degradation and ...

工程学

A Continuous-flow Photocatalytic Reactor for the Precisely Controlled Deposition of Metallic Nanoparticles

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic nanoparticles is developed. Guidelines for the replication of the reactor and its operation are provided in detail. Three different composite systems (Pt/graphene, Pt/TiO2, and Au/TiO2) with monodisperse and uniformly distributed particles are produced by this reactor, and the photodeposition mechanism, as well as the synthesis optimization strategy, are discussed. The synthesis methods and their technical aspects are described comprehensively. The role of the ultraviolet (UV) dose (in each excitation pulse) on the photodeposition process is investigated and the optimum values for each composite system are provided.

For a continuous and scalable synthesis of noble-metal-based nanocomposites, a novel photocatalytic reactor is developed and its structure, operation principles, and product quality optimization strategies are described.

一种用于金属纳米粒子精确控制沉积的连续流动光催化反应器

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic ...

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 ...

A Salt-Templated Synthesis Method for Porous Platinum-based Macrobeams and Macrotubes

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed by rinsing and supercritical drying steps, often resulting in mechanically fragile materials. Here, a method to synthesize nanostructured porous platinum-based macrotubes and macrobeams with a square cross section from insoluble salt needle templates is presented. The combination of oppositely charged platinum, palladium, and copper square planar ions results in the rapid formation of insoluble salt needles. Depending on the stoichiometric ratio of metal ions present in the salt-template and the choice of chemical reducing agent, either macrotubes or macrobeams form with a porous nanostructure comprised of either fused nanoparticles or nanofibrils. Elemental composition of the macrotubes and macrobeams, determined with x-ray diffractometry and x-ray photoelectron spectroscopy, is controlled by the stoichiometric ratio of metal ions present in the salt-template. Macrotubes and macrobeams may be pressed into free standing films, and the electrochemically active surface area is determined with electrochemical impedance spectroscopy and cyclic voltammetry. This synthesis method demonstrates a simple, relatively fast approach to achieve high-surface area platinum-based macrotubes and macrobeams with tunable nanostructure and elemental composition that may be pressed into free-standing films with no required binding materials.

A synthesis method to obtain porous platinum-based macrotubes and macrobeams with a square cross section through chemical reduction of insoluble salt-needle templates is presented.

多孔铂基微波和宏管的盐模板合成方法

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed ...

Localized Bathless Metal-Composite Plating via Electrostamping

Composite plating with particles embedded into the metal matrix can enhance the properties of the metal coating to make it more or less conductive, hard, durable, lubricated or fluorescent. However, it can be more challenging than metal plating, because the composite particles are either 1) not charged so they do not have a strong electrostatic attraction to the cathode, 2) are hygroscopic and are blocked by a hydration shell, or 3) too large to remain stagnate at the cathode while stirring. Here, we describe the details of a bathless plating method that involves anode and cathode nickel plates sandwiching an aqueous concentrated electrolyte paste containing large hygroscopic phosphorescent particles and a hydrophilic membrane. After applying a potential, the nickel metal is deposited around the stagnant phosphor particles, trapping them in the film. The composite coatings are characterized by optical microscopy for film roughness, thickness and composite surface loading. In addition, fluorescence spectroscopy can be used to quantify the illumination brightness of these films to assess the effects of various current densities, coating duration and phosphor loading.

Presented here is a protocol of bathless electroplating, where a stagnant metal salt paste containing composite particles are reduced to form metal composites at high loading. This method addresses the challenges faced by other common forms of electroplating (jet, brush, bath) of embedding composites particles into the metal matrix.

通过电子压图进行本地化无浴金属复合电镀

Composite plating with particles embedded into the metal matrix can enhance the properties of the metal coating to make it more or less conductive, hard, ...

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 ...