根据合同号 DE-AC36-08GO28308 到 NREL, 美国能源部、能源效率和可再生能源办公室提供了财政支助。

1. 铂镍纳米线的合成
<ol><li>要开始置换过程, 在水中悬浮镍纳米线模板并将其加热到90摄氏度。<ol>
<li>在50毫升离心管中加入40毫克的商用, 镍纳米线到20毫升的去离子水。油脂实验5分钟。 注: 纳米线直径约为150-250 纳米, 长度为100-200 µm。</li>
		<li>将悬浮纳米线转移到250毫升的玻璃圆底烧瓶中, 加入60毫升的去离子水。在矿物油浴中加热烧瓶到90°c。搅拌反应混合物在 500 rpm 与聚四氟乙烯桨连接到玻璃轴和电动搅拌器。</li>
	</ol>
</li>
	<li>由自发电偶位移形成 Pt 镍纳米线。<ol>
<li>添加8.1 毫克的 tetrachloroplatinate 钾到15毫升的去离子水。将该解决方案添加到20毫升注射器上, 其端部附有大约8厘米0.318 厘米聚氨酯基油管。将注射器放在自动注射器泵中, 并将其设置为1毫升/分钟。</li>
		<li>启动注射器泵, 并允许泵添加解决方案的圆底烧瓶超过15分钟. 将烧瓶加热90摄氏度, 2 小时。</li>
		<li>离心溶液在 2500 x g 15 分钟, 并倒入上清到废物流。并用重悬 solidswith 浴超声波 (大约十年代) 使用新鲜的解答 (水或2丙醇, 指定)。再次离心溶液, 取出上清液。重复洗涤过程三次与去离子水, 然后一次与2丙醇。</li>
		<li>将铂镍纳米线在一夜间真空烘箱中干燥40摄氏度 (约16小时)。</li>
	</ol>
</li>
</ol>2. 用电感耦合等离子体质谱 (ICP-MS) 检查组合物。
注: 催化剂组成应为7.3 加仑 0.3 .% Pt。
<ol><li>在室温下一夜之间在10毫升的水中消化1毫克的样品。</li>
	<li>稀释到浓度的 200, 20 和 2 ppb, 与基质匹配的稀释到1.5% 盐酸和0.5% 硝酸。<ol>
<li>将20µL 的沼加入9.98 毫升的库存溶液 (1.5% 盐酸和0.5% 硝酸), 用于 200 ppb;2µL 的沼成10.00 毫升的库存溶液 (1.5% 盐酸和0.5% 硝酸) 为 20 ppb;和0.2 µL 的沼成10.00 毫升的股票溶液 (1.5% 盐酸和0.5% 硝酸) 2 ppb。使用0.4 µm 聚四氟乙烯过滤器过滤稀释。</li>
	</ol>
</li>
</ol>3. 铂镍纳米线的退火和酸浸后合成工艺。
<ol><li>氢退火合成的 Pt 镍纳米线。</li>
	<li>将整个纳米线样品添加到管状炉中。夜间将真空应用于管子。 注: 由于煤气流 (氢气、氧气) 在管式炉的高温下使用, 因此需要安全考虑。建立了管-气连接, 以确保该装置在操作过程中能处理真空和500乇的背压。管子出口被排出排气, 整个炉子被放到排气管道的通风柜中。<ol>
<li>用500乇的背压将低流速的氢气喂入管中。</li>
		<li>加热样品到250°c 为2小时, 使用10°c/分钟的舷梯率。</li>
		<li>允许样品自然降温到室温。</li>
	</ol>
</li>
	<li>酸浸出氢退火的 Pt 镍纳米线。<ol>
<li>添加25毫克的纳米线到20毫升的去离子水和浴缸油脂实验。将悬浮纳米线转移到100毫升圆底烧瓶。</li>
		<li>将室温稀释硝酸加入瓶中 (25 毫升0.2 米硝酸至25毫升水/纳米线悬浮液), 使烧瓶的含量为0.1 米硝酸的50毫升, 并摇动烧瓶以确保均匀浓度。立即加入硝酸。</li>
		<li>将烧瓶连接至 Schlenk 线。打开真空10分钟, 然后关闭真空。慢慢地将氮气加入生产线, 让烧瓶在室温下进行2小时的加热. 从 Schlenk 线上取出烧瓶, 然后按照步骤1.2.3 中的说明清洗产品。</li>
		<li>检查组合物与 ICP-MS, 这应该是 15.2, 0.3 .% Pt。</li>
	</ol>
</li>
	<li>氧退火酸浸出铂镍纳米线。<ol>
<li>将纳米线添加到商业上可用的管式炉中。夜间将真空应用于管子。</li>
		<li>用500乇的背压将低流速的氧气输送到管内。</li>
		<li>加热样品到175°c 为2小时, 使用10°c/分钟的舷梯率。</li>
		<li>允许样品自然降温到室温。</li>
	</ol>
</li>
</ol>4. 电化学表征旋转圆盘电极 (RDE) 半电池中的纳米线8
<ol><li>涂上玻碳工作电极。<ol>
<li>添加催化剂, 其中含有73µg Pt, 7.6 毫升的去离子水在20毫升闪烁瓶, 然后添加2.4 毫升的2丙醇。瓶子的内容随后被称为墨水。将墨水加冰5分钟, 然后添加10µL 的商业可用的离子。 注: 为合成和氢退火催化剂, 应使用1毫克 (7.3 .% Pt)。对于酸性浸出和氧退火催化剂, 应使用480µg (15.2 .% Pt)。</li>
		<li>油脂实验墨水在冰, 三十年代由垫铁跟随20分钟由巴恩和三十年代由垫铁。加入7.5 毫升的墨水到0.5 毫克的石墨碳纳米纤维。</li>
		<li>油脂实验墨水在冰, 三十年代由垫铁跟随20分钟由巴恩和三十年代由垫铁。吸管10µL 墨水到玻碳工作电极 (5 毫米外径), 与反转电极旋转 100 rpm。吹打墨水后, 将旋转增加到 700 rpm。</li>
		<li>油脂实验墨水再 (三十年代垫铁, 20 分钟巴恩, 三十年代垫铁), 而电极烘干和吸管另外的墨水 (10 µL) 到电极。继续涂装过程, 将负载增加到1.9 µg cm 电气-2, 五10µL 滴墨水。</li>
	</ol>
</li>
	<li>组装 RDE 测试站。<ol>
<li>将玻璃器皿浸泡在浓硫酸中过夜。然后, 将玻璃器皿一夜间浸泡在商业上可替代的铬酸。在去离子水中煮沸八次。组装玻璃器皿, 将工作, 计数器和参考电极连接到主测试单元。 注意: RDE 半细胞使用三电极配置。工作和计数器电极分别为玻碳和 Pt 网。该参考电极是可逆氢电极 (涌泉), 该 Pt 线包含在玻璃中, 含0.1 米高氯酸电解质。</li>
		<li>用0.1 米高氯酸填充 RDE 半细胞。将工作电极连接到商用的调制速度控制器上, 并将工作电极尖端浸没。</li>
		<li>采取电化学测量与商业可用的恒电位仪。用氮气清洗电解液7分钟。</li>
	</ol>
</li>
	<li>采取电化学表面区域。<ol>
<li>输入参数到恒电位仪制造商提供的自动循环伏安文件中。将周期数设置为 50, 扫描速率为 100 mV s-1, 较低电位为 0.025 V, 上部电位为 1.4 v. 运行循环伏安文件并丢弃电解质。用0.1 米的高氯酸再灌装, 用一氧化碳清除。</li>
		<li>将参数输入到恒电位仪制造商提供的自动潜在保存文件中。将潜在的 0.1 V 和时间设置为20分钟, 并开始在2500转每分钟旋转工作电极。运行潜在的保存文件: 为程序的前10分钟, 清除一氧化碳;对于第二个10分钟的程序, 清除氮气。在去年三十年代的举行, 关闭旋转和设置涌泉, 以覆盖电解质。</li>
		<li>输入参数到恒电位仪制造商提供的自动循环伏安文件中。将周期数设置为 3, 扫描速率为 20 mV s-1, 起始电位为 0.1 v, 电位下限为 0.025 v, 上部电位为1.2 伏, 运行循环伏安文件。</li>
	</ol>
</li>
	<li>采取氧还原极化曲线。<ol>
<li>用氧气清洗电解液至少7分钟, 工作电极旋转 2500 rpm。</li>
		<li>设置氧气清除, 以毯子电解质和减慢工作电极旋转到 1600 rpm。</li>
		<li>输入参数到恒电位仪制造商提供的自动线性扫描伏安文件中。将周期数设置为 10, 扫描速率为 20 mV s-1, 起始电位为-0.1 V, 端电位为 1.05 v, 运行线性扫描伏安文件。放弃电解质。</li>
		<li>再用0.1 米高氯酸, 用氧气清洗至少7分钟. 重新运行步骤4.4.3 中使用的线性扫描伏安文件。</li>
	</ol>
</li>
	<li>运行耐久性测试。<ol>
<li>在 2500 rpm 旋转工作电极时, 用氮气清除电解质。设置氮气清除以覆盖电解质并停止工作电极旋转。</li>
		<li>输入参数到恒电位仪制造商提供的自动循环伏安文件中。将周期数设置为 3万, 扫描速率为 500 mV s-1, 低电位为 0.6 V, 上部电位为 1.0 v, 运行循环伏安文件。</li>
		<li>耐久性后, 使用步骤4.3 和4.4 中提供的协议, 采用电化学表面区域和氧还原极化曲线。</li>
	</ol>
</li>
</ol>

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作者没有什么可透露的。

这些协议已经用于产生扩展表面催化剂与高表面区域和具体活动在氧气减少反应8。通过将 Pt 沉积在纳米结构模板上, 纳米线避免了低协调的场地, 减少了颗粒尺寸效应, 产生了比碳支持的铂纳米粒子高12倍以上的特定活动。利用电偶位移作为合成方法, 在 Ni 模板7上也产生了近似涂层。在 Pt 位移较低的情况下, 该工艺产生的电化学表面面积超过90米2 gPt-1, 这是扩展表面催化剂的重大突破。
需要进行氢退火以提高性能8。退火到高温改善了氧还原特定活动, 这是合理化的合金效应, 由 pt 晶格压缩削弱 pt O 吸附9,10。虽然氢退火步骤改善了初始活性, 但高耐久性和镍溶解损失是一个值得关注的问题。采用酸浸和氧退火的方法将损失降到最低。优化的 pt 镍纳米线产生的氧还原质量活动的十一倍大于碳支持铂纳米粒子和三倍以上的合成线。对纳米线的耐久性也做了重大改进, 损失了3% 质量活动 (合成损失 21%) 和0.3% 的催化剂质量对镍溶解 (合成损失 7%)。
铂镍纳米线已被开发和优化, 其性能在 RDE 半细胞。RDE 测试常用于催化剂筛选, 以评估催化剂的基本性能和电化学性能。然而, RDE 活动并不保证类似的燃料电池性能, 而膜电极组件包括由于大量运输而造成的活动损失, 以及电子和离子电阻。在这些协议中开发的 pt 镍纳米线, 表明了多大程度的高活性铂纳米粒子, 以及提高耐久性。虽然这些结果表明, 铂镍纳米线可以降低燃料电池电极负载, 以满足成本性能指标, 有效地将这些材料纳入膜电极组件仍然是一个重大的挑战。

质子交换膜燃料电池部分受催化剂层所需铂量和成本的限制, 燃料电池成本的一半可能是1。在燃料电池中, 纳米材料通常被开发成氧还原催化剂, 因为反应比氢氧化动力学慢。碳支持铂纳米粒子由于其高的表面面积, 常被用作氧还原催化剂;然而, 它们有特定的选择性活动, 容易产生耐久性损失。
扩展薄膜通过解决这些限制, 为纳米粒子提供了潜在的好处。延长 Pt 表面通常会产生比纳米粒子大得多的特定活动, 通过限制不太活跃的小平面和粒度效应, 并且在可能的循环2、3下显示为持久性。,4. 虽然在扩展表面催化剂中实现了高质量活动, 但主要是通过增加特定活动, 而催化剂类型仅限于 Pt, 低表面积 (10 米2 gPt-1)3,4,5。
自发电偶位移结合腐蚀和电泳的方面6。该工艺一般受两种金属的标准氧化还原电位的控制, 当金属阳离子比模板更具反应性时, 沉积通常发生。位移倾向于产生与模板形态相匹配的纳米结构。将该技术应用于扩展纳米结构, 可以形成铂基催化剂, 利用扩展薄膜的高比氧还原活性。通过部分位移, 少量 Pt 已沉积, 并已产生高表面积的材料 (> 90 米2 gPt-1)7,8。
这些协议涉及氢退火, 以混合 Pt 和镍区和改善氧还原活动。一些研究已经在理论上建立了这种机制, 并在实验中证实了铂氧还原过程中的合金化效应。将 pt OH 和铂 O 结合到氧还原活动的建模和关联表明 pt 改进可以通过格子压缩9,10进行。合金 pt 与较小的过渡金属已经证实了这一好处, 铂镍已被调查的一些形式, 包括多晶硅, 多面电极, 纳米粒子和纳米结构11,12, 13,14。
电偶位移已用于铂氧还原催化剂的开发与各种其他模板, 包括银, 铜, 钴纳米结构15,16,17。该合成技术还用于其他金属的沉积, 并为燃料电池、电解槽和醇类的电化学氧化制备了催化剂18,19,20, 21。类似的协议也可用于合成纳米材料, 具有更广泛的电化学应用。

<table border="0" cellpadding="0" cellspacing="0" style="width:681px;" width="680">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:215px;">Nickel nanowires</td>
			<td style="width:300px;">Plasmachem GmbH</td>
			<td style="width:167px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">250 mL round bottom flask</td>
			<td>Ace Glass</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Hot plate</td>
			<td>VWR International</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Mineral oil</td>
			<td>VWR International</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Potassium tetrachloroplatinate</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Syringe pump</td>
			<td>New Era Pump Systems</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Rotator</td>
			<td>Arrow Engineering</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Teflon paddle</td>
			<td>Ace Glass</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Glass shaft</td>
			<td>Ace Glass</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Split hinge tubular furnace</td>
			<td>Lindberg</td>
			<td></td>
			<td>Customized in-house</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Schlenk line</td>
			<td>Ace Glass</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Condensers</td>
			<td>VWR International</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Nitric acid</td>
			<td>Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">2-propanol</td>
			<td>Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Nafion ionomer (5 wt. %)</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Glassy carbon working electrode</td>
			<td>Pine Instrument Company</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">RDE glassware</td>
			<td>Precision Glassblowing</td>
			<td></td>
			<td>Customized in-house</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Platinum wire</td>
			<td>Alfa Aesar</td>
			<td></td>
			<td>Customized in-house</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Platinum mesh</td>
			<td>Alfa Aesar</td>
			<td></td>
			<td>Customized in-house</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">MSR Rotator</td>
			<td>Pine Instrument Company</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Potentiostat</td>
			<td>Metrohm Autolab</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

synthesis of platinum-nickel nanowires and optimization for oxygen reduction performance

以铂镍 (Pt 镍) 纳米线为燃料电池催化剂, 对氧还原反应的性能和耐久性进行了优化设计。利用自发电偶位移将 Pt 层沉积在镍纳米线基体上。合成方法生产的催化剂具有高特异活性和高 Pt 表面积。氢退火改善了 Pt 和镍的混合和特定的活性。采用酸浸法优先去除纳米线表面附近的镍, 采用氧退火法稳定近表面镍, 提高耐久性, 减少镍的溶解。这些协议详细的优化每个后合成处理步骤, 包括氢退火到250°c, 暴露到0.1 米硝酸, 氧退火到175摄氏度。通过这些步骤, 铂镍纳米线产生的活动比铂纳米粒子的数量级更高, 同时提供了显著的耐久性改进。所提出的协议是基于 Pt 镍系统在燃料电池催化剂的发展。这些技术也被用于各种金属组合, 并可用于发展多种电化学过程的催化剂。

镍纳米线的自发电偶位移与 pt, 使用指定的量, 产生了 pt 镍纳米线的 7.3 .% pt (图 1和图 2A)。为了达到最佳的 pt 负载, 可能需要对 pt 前驱体的数量进行一些修改。Pt 位移对表面 Ni 氧化物层的厚度敏感, 根据模板年龄 (空气暴露) 和上游可变性22的不同可能会有所不同。然而, 该组合物对于确保高活性和 ICP-MS 被用来确保最佳成分至关重要。RDE 测试协议已经包括在内, 因为遵循这些协议对于确认正确的合成和处理参数是至关重要的。这种成分的催化剂 (7.3 .% Pt) 产生了峰值氧还原质量活动7。铂沉积量越高, 电化学表面积越低, 由于铂的利用率较低, 铂层的形成较厚 (图 2b)。较低的 pt 导致了特定活动的降低, 这可能是由于颗粒大小的影响, 虽然活动下降比 Pt 纳米颗粒的结果更温和2。
需要氢退火来集成 pt 和镍区, 并压缩 pt 晶格8。晶格压缩改善氧还原活性和退火到250°c 产生的最佳质量活动 (图 3)。尽管在较高退火温度下, 特定活动继续增加, 但由于铂在表面上重新排列, 电化学表面积可能降低。
虽然氢气退火产生了高氧还原活性, 耐久性测试导致了巨大的性能损失和高数量的镍溶解。酸浸用于优先去除镍, 氧退火用于提高耐久性和最小化镍溶解8,22。酸性浸出到 15.2 .% Pt 和氧退火到175°c 产生最佳活动和耐久性 (表 1)。如果酸性浸出步骤中的镍去除量较大, 则达到了较高的耐久性, 但以初始性能为代价。高 Pt 成分产生的纳米线具有较低的特异活性 (dealloying 效应), 材料的 electrocatalytically 兴趣较小。如果在酸性浸出步骤中镍的去除量减少, 大量的镍仍留在表面。氧退火改善了纳米线表面附近镍的稳定性, 防止了电化学条件下铂点的进入。175°c 的氧退火温度为稳定地下镍的耐久性试验提供了平衡, 同时还允许在调节过程中使用 Pt。对于 15.2 .% Pt 的纳米线, 较高的氧退火温度产生较低的初始活性;相反, 较低的氧退火温度导致了较高的耐久性损失和更高的镍溶解程度。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56667/56667fig1.jpg"> 图 1.自发电偶位移过程示意图.自发电偶位移过程示意图, 用更高贵的金属阳离子 (红色) 取代金属模板 (蓝色)6。重印 (适应) 以允许从 s.m. 其他, 林宏盐和学士 Pivovar, 催化科学 & 技术, 4, 3589 (2014)。版权所有2014英国皇家化学学会。<a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56667/56667fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56667/56667fig2.jpg"> 图 2.合成的铂镍纳米线: 其组成和表面积。() pt 镍纳米线组成作为铂前驱体 (tetrachloroplatinate 钾) 的量的函数, 在电偶位移过程中加入了40毫克的镍纳米丝.(B) 作为合成铂镍纳米线的电化学表面区域, 作为 pt 位移水平的函数7。数据点表示平均值, 而误差条表示测量的标准偏差。转载 (改编) 获得 s.m. 的许可, 如拉森, 美国 Pylypenko, 地方检察官卡伦, d.r. Diercks, 肯塔基州 Neyerlin, Kocha 和学士 Pivovar, ACS 催化, 4, 1114 (2014)。版权所有2014美国化学学会。<a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56667/56667fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56667/56667fig3.jpg"> 图 3.氢退火铂镍纳米线的氧还原质量活性作为退火温度的函数8.数据点表示平均值, 而误差条表示测量的标准偏差。转载 (改编) 征得 s.m. 的许可, c. 非政府组织, S. 应该的, m。Ha, Dameron, j.n. Weker, 肯塔基州 Neyerlin, Kocha, s Pylypenko 和学士 Pivovar, ACS 欧米茄, 2, 1408 (2017)。版权所有2017美国化学学会。<a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56667/56667fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<table fo:keep-together.within-page="1"><tbody>
<tr>
<td>催化剂</td>
			<td>m, i0.9V [mA 毫克Pt\ u20121]</td>
			<td>im, f0.9V [mA 毫克Pt\ u20121]</td>
		</tr>
<tr>
<td>铂镍</td>
			<td>1653</td>
			<td>1339</td>
		</tr>
<tr>
<td>H2
</td>
			<td>5213</td>
			<td>3962</td>
		</tr>
<tr>
<td>酸</td>
			<td>3583</td>
			<td>3153</td>
		</tr>
<tr>
<td>O2
</td>
			<td>5414</td>
			<td>5305</td>
		</tr>
<tr>
<td>铂/HSC</td>
			<td>500</td>
			<td>375</td>
		</tr>
</tbody></table>表1。氧还原质量活动 (im、i) 和以下 (im, f) 半细胞耐久性测试.评价的催化剂包括合成 (Pt 镍), 氢退火 (H2), 酸浸出 (酸) 和氧退火 (O2) Pt 镍纳米线。碳支持铂纳米粒子 (pt/HSC) 的半电池性能也作为参考8提供。转载 (改编) 征得 s.m. 的许可, c. 非政府组织, S. 应该的, m。Ha, Dameron, j.n. Weker, 肯塔基州 Neyerlin, Kocha, s Pylypenko 和学士 Pivovar, ACS 欧米茄, 2, 1408 (2017)。版权所有2017美国化学学会。

Watch this Scientific Journal Video about Synthesis of Platinum-nickel Nanowires and Optimization for Oxygen Reduction Performance at JoVE.com

Synthesis of Platinum-nickel Nanowires and Optimization for Oxygen Reduction Performance

铂镍纳米线的合成及减氧性能优化

该协议描述了铂镍纳米线的合成和电化学测试。用镍纳米线模板的电偶位移合成了纳米丝。采用氢退火、酸浸、氧退火等合成工艺, 优化了氧还原反应中纳米线的性能和耐久性。

Platinum-nickel (Pt-Ni) nanowires were developed as fuel cell electrocatalysts, and were optimized for the performance and durability in the oxygen ...

synthesis-platinum-nickel-nanowires-optimization-for-oxygen-reduction

Nanyang Technological University

Research

JoVE Journal

Chemistry

7.7K 次观看.  National Renewable Energy Laboratory. 该协议描述了铂镍纳米线的合成和电化学测试。用镍纳米线模板的电偶位移合成了纳米丝。采用氢退火、酸浸、氧退火等合成工艺, 优化了氧还原反应中纳米线的性能和耐久性。

视频: Synthesis of Platinum-nickel Nanowires and Optimization for Oxygen Reduction Performance

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.

硒化镉/硫化镉棒和纳米四脚合成种子

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded ...

科研

化学

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability.

Here, we present a protocol with a sol-gel process to synthesize gold intercalated in the walls of mesoporous materials (GMS), which is confirmed to possess a mesoporous matrix with gold intercalated in the walls imparting great stability and recyclability.

合成和金插在介孔二氧化硅的墙壁催化性能

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties ...

Optimization of Synthetic Proteins: Identification of Interpositional Dependencies Indicating Structurally and/or Functionally Linked Residues

Protein alignments are commonly used to evaluate the similarity of protein residues, and the derived consensus sequence used for identifying functional units (e.g., domains). Traditional consensus-building models fail to account for interpositional dependencies &#8211; functionally required covariation of residues that tend to appear simultaneously throughout evolution and across the phylogentic tree. These relationships can reveal important clues about the processes of protein folding, thermostability, and the formation of functional sites, which in turn can be used to inform the engineering of synthetic proteins. Unfortunately, these relationships essentially form sub-motifs which cannot be predicted by simple &#8220;majority rule&#8221; or even HMM-based consensus models, and the result can be a biologically invalid &#8220;consensus&#8221; which is not only never seen in nature but is less viable than any extant protein. We have developed a visual analytics tool, StickWRLD, which creates an interactive 3D representation of a protein alignment and clearly displays covarying residues. The user has the ability to pan and zoom, as well as dynamically change the statistical threshold underlying the identification of covariants. StickWRLD has previously been successfully used to identify functionally-required covarying residues in proteins such as Adenylate Kinase and in DNA sequences such as endonuclease target sites.

Synthetic protein sequences based on consensus motifs typically ignore co-evolving residues, that imply interpositional dependencies (IPDs). IPDs can be essential to activity, and designs that disregard them may result in suboptimal results. This protocol uses StickWRLD to identify IPDs and help inform rational protein design, resulting in more efficient results.

优化合成蛋白质:Interpositional依赖性的鉴定指示在结构和/或功能性连接的残留

Protein alignments are commonly used to evaluate the similarity of protein residues, and the derived consensus sequence used for identifying functional ...

Curtain Flow Column: Optimization of Efficiency and Sensitivity

Active Flow Technology (AFT) is a form of column technology that increases the separation performance of a HPLC column through the use of a specially purpose built multiport end-fitting(s). Curtain Flow (CF) columns belong to the AFT suite of columns, specifically the CF column is designed so that the sample is injected into the radial central region of the bed and a curtain flow of mobile phase surrounding the injection of solute prevents the radial dispersion of the sample to the wall. The column functions as an 'infinite diameter' column. The purpose of the design is to overcome the radial heterogeneity of the column bed, and at the same time maximize the sample load into the radial central region of the column bed, which serves to increase detection sensitivity. The protocol described herein outlines the system and CF column set up and the tuning process for an optimized infinite diameter 'virtual' column.

Here, we present a protocol for the operation and optimization of Active Flow Technology (AFT) column in Curtain flow (CF) mode for enhanced separation performance.

幕式柱:效率和灵敏度的优化

Active Flow Technology (AFT) is a form of column technology that increases the separation performance of a HPLC column through the use of a specially ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

超分子胶体的合成与表征

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation.
We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers.

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

This protocol details the important steps required for the bioconjugation of a cysteine containing protein to a maleimide, including reagent purification, reaction conditions, bioconjugate purification and bioconjugate characterization.

蛋白质生物缀合物的合成<em&gt;通过</em&gt;半胱氨酸马来酰亚胺化学

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the ...

Hydroquinone Based Synthesis of Gold Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag+) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM.

This paper describes a protocol for the synthesis of gold nanorods, based on the use of hydroquinone as reducing agent, plus the different mechanisms for controlling their size and aspect ratio.

金纳米棒基于对苯二酚合成

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the ...

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 ...

Synthesis of Substrate-Bound Au Nanowires Via an Active Surface Growth Mechanism

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a challenge, as it requires asymmetric growth of symmetric crystals. Here, we report a distinctive synthesis of substrate-bound Au nanowires. This template-free synthesis employs thiolated ligands and substrate adsorption to achieve the continuous asymmetric deposition of Au in solution at ambient conditions. The thiolated ligand prevented the Au deposition on the exposed surface of the seeds, so the Au deposition only occurs at the interface between the Au seeds and the substrate. The side of the newly deposited Au nanowires is immediately covered with the thiolated ligand, while the bottom facing the substrate remains ligand-free and active for the next round of Au deposition. We further demonstrate that this Au nanowire growth can be induced on various substrates, and different thiolated ligands can be used to regulate the surface chemistry of the nanowires. The diameter of the nanowires can also be controlled with mixed ligands, in which another &#34;bad&#34; ligand could turn on the lateral growth. With the understanding of the mechanism, Au nanowire-based nanostructures can be designed and synthesized.

We report a solution-based method to synthesize substrate-bound Au nanowires. By tuning the molecular ligands used during the synthesis, the Au nanowires can be grown from various substrates with different surface properties. Au nanowire-based nanostructures can also be synthesized by adjusting the reaction parameters.

通过活性表面生长机制合成基片束缚金纳米线

Advancing synthetic capabilities is important for the development of nanoscience and nanotechnology. The synthesis of nanowires has always been a ...

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 ...