Name: synthesis of bimetallic pt/sn-based nanoparticles in ionic liquids
Uploaded: 2018-08-23T13:30:00.000+00:00
Duration: 7 min 14 s
Description: Watch this Scientific Journal Video about Synthesis of Bimetallic Pt/Sn-based Nanoparticles in Ionic Liquids at JoVE.com

这项工作得到德国科学基金会的支持, 在优先项目 (SPP1708) "材料合成附近的室温" (项目是 2243/3-1 和 2243/3-2)。我们进一步承认赫尔曼霍斯特·科勒的实验性援助, 以及基督教 Kübel 博士和吴王的支持与电子显微学研究。

警告: 使用前请查阅所有相关的材料安全数据表。这些合成中使用的几种化学物质都具有剧毒和致癌性。与散装物相比, 纳米材料可能有额外的危害。在执行综合反应时, 请使用所有适当的安全做法, 包括使用工程控制 (油烟机、手套箱) 和个人防护设备 (安全眼镜、手套、实验室大衣、全长长裤、闭趾鞋)。以下程序涉及标准, 无空气处理 Schlenk 技术使用氩作为惰性气体或使用缺氧手套箱。用聚四氟乙烯环密封或真空润滑脂仔细组装所有玻璃到玻璃接头, 避免与空气接触。在使用前检查所有玻璃器皿是否有缺陷。Triethylborane 是一种发火液体, 与空气接触时燃烧。在无空气条件下, 请注意适当的安全操作和处理。请采用所有适当的安全措施, 使用氢气和任何设备 (高压釜, 气体滴定管) 在高压力下。
1. 还原剂的制备
<ol><li>
triethylborohydride 钾的制备 (K [注3H])
	<ol>
<li>用 Schlenk 线在氩气气氛下, 在400毫升无水 tetrahydrofurane 中悬浮34.5 克 (0.873 摩尔) 的氢化钾, 并将烧瓶加热至3摄氏度, 搅拌时用搅拌棒。</li>
		<li>用注射器, 添加100毫升 (0.71 摩尔) 的 triethylborane 滴-明智 (~ 1 下降/秒) 的搅拌悬浮氢化钾在 tetrahydrofurane。</li>
		<li>将反应混合物冷却到-40 摄氏度, 通过过滤去除任何过量的氢化钾。</li>
		<li>在 tetrahydrofurane 中获得 triethylborohydride 钾作为一种无色透明的溶液。</li>
	</ol>
</li>
	<li>
甲基三辛基 triethylborohydride 的制备 ([OMA] [注3H])
	<ol>
<li>在氩气气氛下, 将50克 (0.11 摩尔) 甲基三辛基溴在100毫升无水 tetrahydrofurane 中溶解在500毫升2颈圆底烧瓶中。</li>
		<li>在室温下, 加入100毫升 K [注3H] 溶液 (1.5 米 tetrahydrofurane), 以解决 tetrahydrofurane 中的 trioctylmethylammonium 溴化物。</li>
		<li>用搅拌棒在室温下搅拌3小时, 然后在一夜之间冷却至-40 摄氏度。</li>
		<li>通过过滤冷却溶液去除溴化钾。</li>
		<li>接收 [OMA] [下注3H] 作为一个明确的解决方案在 tetrahydrofurane。</li>
	</ol>
</li>
</ol>2. 甲基三辛基双 (trifluoromethylsulfonyl) 酰亚胺的治疗 ([OMA] [NTf2])
<ol><li>在使用之前, 干燥和加氢 [OMA] [NTf2] 在真空 (10-3毫巴) 在70°c 为 3 h 和在真空 (10-4毫巴) 在室温下为另 16 h。</li>
</ol>3. 铂/锡基纳米粒子的合成
<ol><li>
铂锡基纳米晶的合成
	<ol>
<li>在氩气气氛中, 共用两个金属盐前体的0.25 毫摩尔。将 Pt2 +和 Sn2 +前体的摩尔比率调整为1:1 和 3:1, 以实现不同成分的随机合金纳米粒子:<ol>
<li>铂/锡纳米粒子的合成 (pt 的1:1 摩尔比: sn 前驱体), 暂停33.2 毫克的 PtCl2和29.6 毫克的 Sn (ac)2 (或23.7 毫克的 SnCl2, 相应) 在4毫升 [OMA] [NTf2] 在100毫升 Schlenk 瓶和搅拌与搅拌在真空线下的2-3 小时, 在60-80 摄氏度的酒吧。</li>
			<li>铂/锡样品的合成 (pt 的3:1 摩尔比: Sn 前驱体), 暂停49.9 毫克的 PtCl2与14.8 毫克的 Sn (ac)2 (或11.9 毫克的 SnCl2, 相应) 在4毫升 [OMA] [NTf2] 在100毫升 Schlenk 瓶和搅拌与搅拌在真空线下的2-3 小时, 在60-80 摄氏度的酒吧。</li>
		</ol>
</li>
		<li>将悬浮液置于室温下的超声波浴中1-2 小时。</li>
		<li>在60-80 摄氏度, 迅速注入3毫升 [oma] [投注3H] 解决方案 (1.23 米在 tetrahydrofurane) 与3毫升注射器的金属盐前体 [OMA] [NTf2], 同时大力搅拌。快速注射产生一个尖锐的成核事件, 促进小规模和狭窄的大小分布。让反应继续, 而搅拌在60-80 °c 为2-3 小时。</li>
		<li>冷却到室温, 并在0.5 小时内清除真空中的任何挥发性化合物。</li>
		<li>获得铂/锡基粒子作为一个高度稳定的胶体溶胶在 [OMA] [NTf2]。</li>
	</ol>
</li>
	<li>
Pt/锡基纳米晶的分离
	<ol>
<li>
铂锡基纳米晶的沉淀
		<ol>
<li>加入3毫升无水乙腈或 tetrahydrofurane 溶液, 凝聚纳米晶。将悬浮液转移到手套箱中的小瓶上, 用瓶盖关闭瓶子, 离心机为15分钟 (4226 x g)。</li>
			<li>醒酒解决方案。丢弃上清液, 用无水乙腈或 tetrahydrofurane 洗涤沉淀。</li>
			<li>将微粒作为含有 Pt/Sn 纳米粒子的粘性粉末, 除了一些残留的 IL。</li>
			<li>通过 XRD 分析, 确定了铂锡基纳米晶的晶体结构和组成。对下布拉格角的反射的转移表明铂纳米粒子与锡的合金化。根据下面的公式, 用谢瑞方程对 XRD 模式的粒度进行估计 <img alt="Equation 1" src="/files/ftp_upload/58058/58058eq1v3.jpg"> Lhkl是钯/Sn 纳米晶的直径 (nm), 垂直于hkl, λ波长 (纳米) (通常铜 Kα 0.154 nm), β峰值宽度在半最大, θ的布拉格角。</li>
			<li>用电感耦合等离子体发射光谱法测定金属含量和成分。 注: 粒子的组成可以通过改变金属前驱体的性质和铂-锡前驱比来调整。以铂/锡为基纳米粒子, 合成了从白金 (ii.) 氯 (PtCl2) 和锡 (ii) 乙酸盐 (ac)2) (pt: sn 前体比3:1 或 1:1), 屈服于随机合金型 Pt/Sn 纳米粒子。详情见参考资料 [c. 席尔德, d. 王, Kübel, s Behrens, z Anorg。Allg。化学.2017, 643, 120-129]25。</li>
		</ol>
</li>
		<li>
铂锡基纳米晶的提取 注: 将纳米粒子从 il 转化为常规有机溶剂 (即正己烷), 在 il 中加入2毫升 n-oleylsarcosine (10-% 的己烷) 和2毫升乙腈到1毫升的纳米微粒溶胶。<ol>
<li>在正己烷 (10) 和1毫升无水乙腈中加入2毫升 n-oleylesarcosine, 在 n-己烷中提取纳米晶。震动后, 通过对 IL 相的脱色和正己烷相的黑色着色, 直观地监测相转移。</li>
			<li>在碳覆盖的铜网格上沉积一滴溶液, 通过透射电镜进行分析。</li>
		</ol>
</li>
	</ol>
</li>
</ol>4. 催化试验
注: 在催化测试中, 使用装有聚四氟乙烯衬垫的反应器、机械吹炼搅拌器 (聚四氟乙烯) 和挡板 (不锈钢) 的半连续釜式反应器, 以实现气体与液相之间的亲密混合, 热电偶和暖气浴。
<ol><li>
α、β-不饱和醛的选择性加氢
	<ol>
<li>加入2.2 毫克 (17 毫摩尔) 的 cinnaic 醛 (CAL) 在30毫升无水 tetrahydrofurane 在惰性气体。</li>
		<li>在缺氧手套箱中, 结合1毫升纳米微粒溶液。</li>
		<li>将反应堆放在加热浴缸中, 用氢气加压。在催化实验中, 将氢气压力常数保持在10巴, 而氢气通过500 毫升的气体滴定管连续供给反应堆。</li>
		<li>将温度提高到摄氏80摄氏度。在 80°c, 开始搅拌使用吹搅拌器 (1200 rpm)。用氢气装载反应堆开始反应。</li>
		<li>根据气体滴定管中的压降, 连续记录氢气消耗量。为了确定催化活性和选择性, 每30分钟服用整除数。</li>
		<li>用柱 (30m x 0.25mm, 0.25µm 膜厚度) 对反应产物进行气相色谱分析。</li>
		<li>根据以下公式计算转频 (飞行时)、产品选择性 (SCAOL [%]) 和肉桂醇 (CAOL) 产量 ([%]) <img alt="Equation" src="/files/ftp_upload/58058/58058eq3v3.jpg"> 
		    <img alt="Equation" src="/files/ftp_upload/58058/58058eq4v2.jpg"> 
		    <img alt="Equation" src="/files/ftp_upload/58058/58058eq5v2.jpg"> 其中t为反应时间 (h), n0, cal初始量的 cal (摩尔), n金属/催化剂的数量的金属催化剂 (摩尔), 和Xt, cal的转换的 cal 在时间 t (%)。[CAOL], [HCAOL] 和 [HCAL] 提到肉桂酒精、hydrocinnamic 酒精和 hydrocinnamic 醛的浓度 (参见反应方案图 2), 分别。 注: 有关详细信息, 请参阅参考25。</li>
	</ol>
</li>
</ol>

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我们没有什么可透露的。

金属盐前体在 [OMA] [NTf2] 中经过精心的溶解, 在夜间搅拌反应混合物, 其次是超声波。这是实现铂/锡纳米粒子的均匀组成和大小的一个重要步骤。OMA[注3H](作为 tetrahydrofurane 的解决方案) 然后用注射器快速注射, 同时大力搅拌粘性溶液。快速注入和混合两个组分是实现单分散和均质纳米粒子的先决条件, 可能会限制程序的放大。成功的纳米粒子形成可以由黄色到黑色溶液的颜色变化来监测。在此步骤中, H2是作为一个侧面产品生成的, 因此, 必须在氩流中执行还原步骤, 以避免反应容器加压。在纳米粒子合成的所有步骤中, 必须防止接触空气和湿气。Pt/Sn 纳米粒子是在 il 注入还原剂后形成的, 其中 il 阳离子和 IL 阴离子同时控制成核和生长过程25。因此, 非常小的纳米粒子在 [NTf2] 中形成一个异常稳定的胶体溶胶。这种合成方法不需要使用额外的, 强烈的协调配体, 并可进一步利用, 以实现各种单和双金属组成的小纳米粒子。
鉴于准均匀催化应用, 纳米粒子在 IL 中固定化的溶胶非常有趣。然而, 微粒的分离 (例如, 为微粒特征) 结果是相当挑战性的由于高胶体稳定性在 IL。通过 tetrahydrofurane 和连续离心的沉淀, 将颗粒分离为粘性粉末。这是一个有用的步骤, 关于纳米粒子的表征,例如, 通过 TEM 或 XRD 分析。另外, 在 n-己烷和乙腈中加入一个协调配体 (即n-oleylsarcosine) 后, 纳米粒子可以被另外功能化并提取到传统溶剂中。样品然后进一步处理象一个常规微粒溶胶。一般而言, 特定的表面特性通常需要对纳米粒子的某些生物医学或技术应用而言。由于颗粒与表面的协调性较弱, 因此可以方便地替代其它配体。因此, 可以根据应用程序的特定要求, 使用当前的合成过程来设计表面特性。基于小型、超顺磁性钴纳米粒子的磁性液体, 是用不同的脂肪族或芳香载体介质 (如煤油、AP201 或爱德华兹 L9) 在类似程序3、4 的情况下制备的..纳米粒子萃取后, 可以回收和重复使用纳米粒子合成。
通过在 tem 网格上沉积纳米粒子溶胶的薄膜, 对颗粒进行透射电镜分析。在这里, 电子光束中 IL 的分解和 TEM 样品的连续污染可能是对小纳米粒子图像的一个真正的挑战。另外, 将沉淀的纳米粒子沉积在 tem 网格上, 并通过 tem 分析研究。在这种情况下, 粒子通常形成高度聚集的结构。图 1a-d显示了纳米粒子在 IL 中的透射电镜图像, 显示了2-3 纳米直径的非常小和规则纳米粒子。对于所有样品, TEM-EDX 分析证实了锡和铂在微粒 (图 1e) 的存在。
为了显示纳米粒子的合金化特征和随机合金型结构, 对纳米微粒粉末进行了 x 射线衍射分析。XRD 模式证实了面中心立方 (fcc) 和随机合金型结构的粒子 (图 1f)。随机合金结构是双金属纳米粒子中最常见的形式之一, 其中两个元素随机 (或几乎随机) 分散在纳米粒子中。对于 Pt 锡系统, 也形成了一些金属间化合物是已知的 (即, PtSn, PtSn4, PtSn2, pt2sn3, 铂3sn)17,26。有序的金属间和无序的随机合金结构, 可以区分的存在和没有额外的衍射模式衍生的超晶格结构。fcc 铂相在40°、45°、68°和 82° (2) 对应于 (111)、(200)、(220) 和 (311) 平面上有反射。对于所有铂/锡基纳米粒子, XRD 模式显示了 fcc 铂相的四特征反射。与纯铂参考的反射位置相比, 铂/锡基纳米粒子的反射被转移到较小的布拉格角。这转移到更小的布拉格角度表明晶格参量的增量由锡原子的插入入 fcc 白金格子。在 XRD 模式中, 没有观察到金属间相 (即Pt3Sn) 中原子序的特征的反射。这意味着形成一个合金化的纳米粒子核心, 随机分布的铂和锡。PdCl2到 Sn (ac)2前体比从3:1 到1:1 的减少另外导致小 SnO2纳米粒子在接近的接触到随机合金型 Pt/Sn 纳米粒子。SnO2是由 Sn (ac)2前驱体的分解形成的。如果 Sn (ac)2的反应与 [OMA] [注3H] 在相同的反应条件下, 在铂前体的缺席, SnO 和 SnO2获得作为主要反应产品。如果 Sn (ac)2被锡 (II) 氯化物 (SnCl2) 所取代, 并在铂前驱体 (PtCl2) 的存在下与 [OMA] [下注3H] 反应, 则完全非晶态粒子形成, 没有 SnO2是检测。通过特维德分析确定晶格常数, 可以进一步分析纳米粒子核中的锡含量。根据维加德定律, 晶格参数在纯铂纳米粒子 (3.914 Å) 和 pt3Sn 相 (4.004 Å) 的晶格参数之间呈线性增加。按照这种方法, 晶纳米粒子核心中的锡被计算为 11% (即, 对于一个 PtCl2 /sn (ac)2前体比 3:1) 和增加到 18% (即PtCl2 /sn (ac)2前体比率为 1:1)。21% 和55% 的总锡含量分别由电感耦合等离子体发射光谱法测定, 从而超过了纳米粒子核中的锡量。更高的整体锡含量可以被分配到另外的形成 SnO2 (即, 大约 26%) 和某些分离的锡原子在纳米粒子表面。x 射线光电子能谱进一步证实了 Pt0/sn0 (即PtCl2到 Sn (ac)2前体比 3:1) 和 pt0/Sn0与 20% SnO2相结合的存在。(即, 对于 PtCl2到 sn (ac)2前驱体比 1:1) 在 Pt/锡基纳米粒子, 这是符合 x 射线衍射分析的结果25。由于有限的晶体尺寸, 谢瑞的扩大产生了峰值。纳米粒子的尺寸是用谢瑞方程计算的, 用铂/锡基纳米粒子的 2.4 nm (即pt: sn 1:1), 2.5 nm (即pt: sn 3:1), 并为 pt 纳米粒子参考, 分别为 2.7 nm, 这是与 TEM 分析结果一致。
α、β-不饱和醛通过选择性加氢转化为不饱和醇, 是催化化学的基础, 也是各种精细化学品25、27生产的关键步骤。虽然热力学倾向于饱和醛的形成, 但在双金属铂基催化剂上, 通过调整它们的尺寸、组成和支撑, 对不饱和醇的形成有选择性。材料。将阳性金属 (例如, 锡) 加入铂, 导致铂 d 带的电子改性, 降低了不饱和醛27的 c = c 键的结合能。电子亏缺的 Sn 原子可能进一步扮演刘易斯酸吸附点为羰基基团28。此外, 在接近 Pt 的 SnO2-x斑块中的空氧点也被证明可以促进羰基的吸附, 并通过附近的铂金点 29提供氢原子的随后加氢。总的来说, 这些例子表明, 双金属铂基催化剂的催化性能受复杂的一系列因素的制约。在本协议中, 我们用肉桂醛加氢作为模型反应, 不仅可以探讨 IL 稳定纳米粒子的整体催化性能, 而且进一步阐明了锡合金化对 Pt 活性和选择性的影响。纳米 粒子。图 2显示了 CAL 加氢过程中可能出现的通路和主要反应产物。首先, 对 Pt 参考纳米粒子的催化性能进行了试验。在这种情况下, 饱和醛 (即HCAL) 是在 3 h 反应后获得的唯一反应产物, 而 cal 转换Xcal是 5% (3 h) 和 9% (22 h), 因此。在双金属纳米粒子中用 Sn 合金化 Pt 后, 产品选择性明显地转向不饱和乙醇 (即CAOL) (图 3)。选择性SCAOL为 100% (即, 对于由摩尔 PtCl2/sn (ac)2比 1:1), 80% (即, 为摩尔合成的粒子 PtCl2 /sn (ac)2比值为 3:1) 和 83% (即, 对于由摩尔 PtCl2 /SnCl2比1:1 的粒子合成的颗粒) 经过 3 h 的反应, 从而进一步受实际纳米颗粒成分的影响。从28小时-1到 8 h-1为由摩尔 PtCl2 /Sn (ac)2比3:1 和 1:1, 分别和 7 h-1的粒子合成的微粒使用 SnCl2代替Sn (ac)2与摩尔 PtCl2/SnCl2比 1:1, 因此。cal 转换Xcal是 25% (3h) 和 84% (22h) 为铂/锡基纳米粒子 (i., 摩尔 PtCl2 /sn (ac)2比 3:1), 这导致最高的产量在 CAOL (YCAOL 20% (3 h))在本研究中研究的纳米粒子中。为了评价系统的整体催化性能, 需要考虑到催化选择性和活性两方面, 因此, 用初始摩尔 PtCl2/sn (ac) 2 制备 Pt/锡纳米粒子比3:1 明显优于所有其他铂和铂/锡基粒子研究的肉桂醇产量。因此, 在这种情况下, 良好的催化性能似乎是由于锡掺杂的 Pt 纳米粒子平衡活性和选择性的肉桂醇在系统中。必须指出的是, 使用相同反应条件, 但没有纳米粒子催化剂的空白实验没有显示任何转化的肉桂醛后22小时的反应。
通过利用 ILs 的有益物理化学性质, 我们展示了一种用于控制随机合金型结构的小、Pt/锡基纳米粒子制备的合成方法。类似的共沉淀方法已经应用到广泛的双金属纳米粒子在传统溶剂中, 我们预计, 这两种类型的随机合金和金属间纳米粒子, 可以获得的这种方法, 将继续扩大。纳米粒子在肉桂醛催化加氢中具有很有趣的催化性能, 对 Pt/锡基纳米粒子的α、β-不饱和肉桂醇的选择性显著提高。

ILs 代表室温熔融盐的大有机阳离子与非对称替代模式。它们以其不寻常的物理化学性质而闻名。il 属性可以通过不同的 il 阳离子和阴离子组合来调节, 现在, 大量的 ILs 在商业上是可用的。最近, 科学家开始使用 ILs 作为反应介质的合成纳米粒子由于其模块化和优良的溶剂性能, 低蒸气压, 高极性和宽电化学稳定窗口1,2,3,4。
在过去的十年中, 双金属纳米粒子引起了相当大的关注, 因为它们表现出多种功能和显著的催化活性, 选择性以及热和/或化学稳定性的 monometallic对应5,6,7,8,9,10。由于协同作用, 修改后的电子和/或几何表面结构, 高催化活性和选择性可以实现化学转化, 即使其中一个成分是少, 甚至不活跃11。虽然纳米粒子的可控合成近年来发展迅速, 但对于双金属纳米晶的合成, 仍然需要对成核和生长阶段进行更精确的控制。由于不同金属涉及双金属纳米晶, 原子分布不仅影响最终的纳米粒子体系结构, 而且对催化性能也有很大作用。催化性能是高度敏感的性质的原子排序 (即, 随机合金与金属间化合物), 即使组成和化学计量是完全相同的。令人惊讶的是, 到目前为止,对于双金属催化剂12、13、14、15的控制合成, ILs 的吸引力特性较少探索,16。
在本协议中, 我们将展示如何利用 ILs 的不寻常性质来合成双金属、随机合金型纳米粒子。在这里, 非常小的纳米粒子的均匀大小可以合成不添加辅助配体在中等反应温度。核和生长过程由 IL 固有的、弱阳离子/阴离子相互作用直接控制。铂锡基纳米粒子的几种方法是已知的, 然而, 这些合成协议通常涉及支持和/或稳定剂 (即, 相当强的协调表面活性剂或配体)17。吸附在纳米颗粒表面上的配体/表面活性剂可以改变甚至抑制催化性能, 并且经常需要连续地去除 (例如通过热处理) 催化应用。该协议产生了基于 IL 的纳米粒子溶胶异常高的胶体稳定性, 而不添加如此强烈的协调配体。在 ILs 中稳定的纳米粒子在广泛的催化反应中发现了一些有趣的特性, 如准均质催化剂18、19、20、21、22 ,23,24。本协议将α、β-不饱和醛 (即肉桂醛) 的选择性加氢作为一种模型反应, 用于研究 IL 稳定纳米粒子的催化性能以及锡合金化对催化活性和选择性25。
本议定书旨在阐明实验性合成程序的细节, 并帮助该领域的新从业者避免许多与在 ILs 中合成纳米粒子有关的常见缺陷。材料特性的详细资料载于前一出版物25。

<table><tbody><tr><td>Platinum(II) acetate (PtCl&lt;sub&gt;2&lt;/sub&gt;)</td><td>Acros</td><td>ACRO369670010</td><td>99%, anhydrous, toxic</td></tr><tr><td>Tin(II) acetate (Sn(ac)&lt;sub&gt;2&lt;/sub&gt;)</td><td>Strem</td><td>50-1975</td><td>99%</td></tr><tr><td>Tin(II) chloride (SnCl&lt;sub&gt;2&lt;/sub&gt;)</td><td>Sigma Aldrich</td><td>452335</td><td>98%; harmful</td></tr><tr><td>Methyltrioctylammonium&lt;br/&gt; bis(trifluoromethylsulfonyl) imide ([OMA][NTf&lt;sub&gt;2&lt;/sub&gt;])</td><td>IoLitec</td><td>IL-0017-HP</td><td>99 %; n.a.; H&lt;sub&gt;2&lt;/sub&gt;O &amp;lt; 100 ppm; halides &amp;lt; 100 ppm</td></tr><tr><td>Tetrahydrofurane</td><td>Sigma Aldrich</td><td>186562</td><td>99.9 %; anhydrous; carcinogenic</td></tr><tr><td>Acetonitrile</td><td>Sigma Aldrich</td><td>271004</td><td>99.8%; anhydrous; harmful</td></tr><tr><td>n-Hexane</td><td>Sigma Aldrich</td><td></td><td>95%, flammable, carcinogenic, toxic</td></tr><tr><td>(Trans)-cinnamaldehyde</td><td>Sigma Aldrich</td><td>14371-10-9</td><td>99%; irritant</td></tr><tr><td>Methyltrioctylammonium bromide</td><td>Sigma Aldrich</td><td>365718</td><td>97%; irritant</td></tr><tr><td>Potassium hydride (KH)</td><td>Sigma Aldrich</td><td>215813</td><td>30 wt.-% dispersion in mineral oil; corrosive</td></tr><tr><td>Triethylborane (B(Et)&lt;sub&gt;3&lt;/sub&gt;)</td><td>Witco</td><td>257192</td><td>95%; toxic, pyrophoric</td></tr><tr><td>N-oleylsarcosine (Korantin-SH)</td><td>BASF</td><td></td><td></td></tr><tr><td>H&lt;sub&gt;2&lt;/sub&gt;</td><td>Air Liquide</td><td></td><td>99.9 %, flammable</td></tr></tbody></table>

synthesis of bimetallic pt/sn-based nanoparticles in ionic liquids

本文演示了一种由 Pt 和 Sn 组成的双金属纳米粒子的合成方法。采用合成策略, 利用离子液体的特定物理化学性质控制成核和生长过程。纳米粒子形成胶体溶胶, 在 IL 的胶体稳定性非常高, 这是特别有趣的, 因为他们的用途作为准均质催化剂。介绍了在常规溶剂中纳米粒子萃取和纳米颗粒沉淀的过程。利用电感耦合等离子体原子发射光谱 (ICP)、X 射线衍射分析 (XRD) 和透射电镜 (TEM) 和能量色散法确定了合成纳米晶的大小、结构和组成。x 射线光谱学 (EDX)。由此, 我们表明, 纳米晶是随机型合金和小 (2-3 纳米) 的大小。在半连续间歇式反应器中测试了α、β-不饱和醛加氢的催化活性和选择性。在这种情况下, 双金属 Pt/锡基纳米粒子对不饱和乙醇具有较高的选择性。

为纳米粒子 (图 1) 收集了 XRD 和透射电镜 (TEM) 图像, 用于识别纳米结构的尺寸、相和形貌。利用能量色散 X 射线光谱 (EDX) 和电感耦合等离子体发射光谱法测定了纳米粒子的元素组成。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/58058/58058fig1.jpg"> 图1。具有随机合金型 Pt/Sn 纳米粒子粒径分布的典型 TEM 图像.用氯化铂 (ii) 和锡 (ii.) 乙酸前体 (a) 在摩尔 Pt 中制备纳米微粒: 在摩尔 pt 中, 3:1 和 (b, c) 的 sn 前驱比: sn 前体比1:1 和 (d) 使用铂 (ii) 氯化物和锡 (ii) 氯前体在摩尔 pt: Sn 比为1:1。(e) 具有代表性的双金属 Pt/锡基粒子的能量色散 X 射线谱, 证实了 sn 和 Pt 的存在. (铜信号来源于支撑铜网格)。(f) 铂/锡基纳米粒子的 XRD 模式与铂纳米颗粒的参考相比较。<a href="https://www.jove.com/files/ftp_upload/58058/58058fig1large.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/58058/58058fig2.jpg"> 图2。在肉桂醛 (CAL) 加氢过程中反应通路和主要反应产物 (即肉桂醇 (CAOL)、hydrocinnamic 醛 (HCAL) 和 hydrocinnamic 醇 (HCAOL)) 的示意图表示。羰基键对不饱和醇的选择性加氢是各种精细化学品合成的关键步骤。通过在 pt/锡基纳米粒子中采用 sn 合金化 pt, 可以选择性地氢化羰基键, 以产生不饱和乙醇 (即CAOL) 作为主要反应产物。<a href="https://www.jove.com/files/ftp_upload/58058/58058fig2large.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/58058/58058fig3.jpg"> 图3。用铂 (ii.) 氯化物和锡 (ii) 酯在 pt 中制备的随机合金型 Pt/Sn 纳米粒子催化加氢中肉桂醛 (CAL) 的转化和选择性的时间过程: (a) 1:1 和 (b) 3:1 (反应条件:80 °c, 10 bar H2)。虽然 CAOL 选择性较低的纳米粒子与 Pt: Sn 前体比 3:1 (b), 增强的 CAL 转化导致较高的产量在 CAOL。<a href="https://www.jove.com/files/ftp_upload/58058/58058fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Synthesis of Bimetallic Pt/Sn-based Nanoparticles in Ionic Liquids at JoVE.com

Synthesis of Bimetallic Pt/Sn-based Nanoparticles in Ionic Liquids

介绍了一种在离子液体中合成双金属纳米粒子的方法及其在不饱和醛选择性加氢中的催化试验过程。

离子液体中双金属 Pt/锡基纳米粒子的合成

We demonstrate a method for the synthesis of bimetallic nanoparticles consisting of Pt and Sn. A synthesis strategy is used in which the particular ...

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9.0K 次观看.  Karlsruhe Institute of Technology (KIT). 介绍了一种在离子液体中合成双金属纳米粒子的方法及其在不饱和醛选择性加氢中的催化试验过程。

视频: Synthesis of Bimetallic Pt/Sn-based Nanoparticles in Ionic Liquids

Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents

Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. Isonicotinic acid, or its derivatives, are coupled to variable length diaminoalkane chains under an inert atmosphere in anhydrous DMF or DMSO with the use of a weak base, triethylamine, and a coupling agent, 1-propylphosphonic anhydride. The products precipitate from solution upon formation or can be precipitated by the addition of water. If desired, the ligands can be further purified by recrystallization from hot water. Dinuclear platinum complex synthesis using the bispyridine ligands is done in hot water using transplatin. The most informative of the chemical characterization techniques to determine the structure and gross purity of both the bispyridine ligands and the final platinum complexes is 1H NMR with particular analysis of the aromatic region of the spectra (7-9 ppm). The platinum complexes have potential application as anticancer agents and the synthesis method can be modified to produce trinuclear and other multinuclear complexes with different hydrogen bonding functionality in the bridging ligand.

This protocol describes the use of amide coupling reactions of isonicotinic acid and diaminoalkanes to form bridging ligands suitable for use in the synthesis of multinuclear platinum complexes, which combine aspects of the anticancer drugs BBR3464 and picoplatin.

酰胺偶联反应为双吡啶基配体及其络合合成，以白金为双核抗癌药物

Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. ...

科研

化学

Reverse Microemulsion-mediated Synthesis of Monometallic and Bimetallic Early Transition Metal Carbide and Nitride Nanoparticles

A reverse microemulsion is used to encapsulate monometallic or bimetallic early transition metal oxide nanoparticles in microporous silica shells. The silica-encapsulated metal oxide nanoparticles are then carburized in a methane/hydrogen atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal carbide nanoparticles. During the carburization process, the silica shells prevent the sintering of adjacent carbide nanoparticles while also preventing the deposition of excess surface carbon. Alternatively, the silica-encapsulated metal oxide nanoparticles can be nitridized in an ammonia atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal nitride nanoparticles. By adjusting the reverse microemulsion parameters, the thickness of the silica shells, and the carburization/nitridation conditions, the transition metal carbide or nitride nanoparticles can be tuned to various sizes, compositions, and crystal phases. After carburization or nitridation, the silica shells are then removed using either a room-temperature aqueous ammonium bifluoride solution or a 0.1 to 0.5 M NaOH solution at 40-60 &#176;C. While the silica shells are dissolving, a high surface area support, such as carbon black, can be added to these solutions to obtain supported early transition metal carbide or nitride nanoparticles. If no high surface area support is added, then the nanoparticles can be stored as a nanodispersion or centrifuged to obtain a nanopowder.

A &#8220;removable ceramic coating method&#8221; is presented in visual format for the synthesis of non-sintered and metal-terminated monometallic and bimetallic early transition metal carbide and nitride nanoparticles with tunable sizes and crystal structures.

单金属和双金属前过渡金属碳化物和氮化物纳米粒子的反相微乳液介导的合成

A reverse microemulsion is used to encapsulate monometallic or bimetallic early transition metal oxide nanoparticles in microporous silica shells. The ...

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

合成，表征和混合金/硫化镉和Au / ZnS核/壳纳米颗粒功能化

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

Generation of Zerovalent Metal Core Nanoparticles Using n-(2-aminoethyl)-3-aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of n-(2-aminoethyl)-3-aminosilanetriol is presented. This compound can be used to effectively reduce and complex metal salts into metal core nanoparticles coated with the compound. By controlling the concentrations of salt and silane one is able to control reaction rates, particle size, and nanoparticle coating. The effects of these changes were characterized through transmission electron microscopy (TEM), UV-Vis spectrometry (UV-Vis), Nuclear Magnetic Resonance spectroscopy (NMR) and Fourier Transform Infrared spectroscopy (FTIR). A unique aspect to this reaction is that usually silanes hydrolyze and cross-link in water; however, in this system the silane is water-soluble and stable. It is known that silicon and amino moieties can form complexes with metal salts. The silicon is known to extend its coordination sphere to form penta- or hexa-coordinated species. Furthermore, the silanol group can undergo hydrolysis to form a Si-O-Si silica network, thereby transforming the metal nanoparticles into a functionalized nanocomposites.

Generation of Zerovalent Metal Core Nanoparticles Using n-2-aminoethyl-3-aminosilanetriol

A novel method for metal core nanoparticle synthesis using a water stable silanol is described.

使用N-零价金属芯纳米粒子的生成（2-氨基乙基）-3- aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of ...

The Synthesis of [Sn10(Si(SiMe3)3)4]2- Using a Metastable Sn(I) Halide Solution Synthesized via a Co-condensation Technique

The number of well-characterized metalloid tin clusters, synthesized by applying the disproportionation of a metastable Sn(I) halide in the presence of a sterically demanding ligand, has increased in recent years. The metastable Sn(I) halide is synthesized at&#160;&#34;outer space conditions&#34; via the preparative co-condensation technique. Thereby, the subhalide is synthesized in an oven at high temperatures, around 1,300 &#176;C, and at reduced pressure by the reaction of elemental tin with hydrogen halide gas (e.g., HCl). The subhalide (e.g., SnCl) is trapped within a matrix of an inert solvent, like toluene at -196 &#176;C. Heating the solid matrix to -78 &#176;C gives a metastable solution of the subhalide. The metastable subhalide solution is highly reactive but can be stored at -78 &#176;C for several weeks. On heating the solution to room temperature, a disproportionation reaction occurs, leading to elemental tin and the corresponding dihalide. By applying bulky ligands like Si(SiMe3)3, the intermediate metalloid cluster compounds can be trapped before complete disproportionation to elemental tin. Hence, the reaction of a metastable Sn(I)Cl solution with Li-Si(SiMe3)3 gives [Sn10(Si(SiMe3)3)4]2- 1 as black crystals in high yield. 1 is formed via a complex reaction sequence including salt metathesis, disproportionation, and degradation of larger clusters. Further, 1 can be analyzed by various methods like NMR or single crystal X-ray structure analysis.

The Synthesis of [Sn10SiSiMe334]2- Using a Metastable SnI Halide Solution Synthesized via a Co-condensation Technique

The disproportionation reaction of a metastable Sn(I) chloride solution, obtained via the preparative co-condensation technique, is used for the synthesis of a metalloid tin cluster compound.

的合成[锡<sub&gt; 10</sub&gt;（SI（SIME<sub&gt; 3</sub&gt;）<sub&gt; 3</sub&gt;）<sub&gt; 4</sub&gt;]<sup&gt; 2</sup<sup&gt; -</sup&gt;使用亚稳锡（I）卤溶液通过共缩聚合成技术

The number of well-characterized metalloid tin clusters, synthesized by applying the disproportionation of a metastable Sn(I) halide in the presence of a ...

In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Combinations of metal oxide semiconductors and gold nanoparticles (AuNPs) have been investigated as new types of materials. The in situ synthesis of AuNPs within the interlayer space of semiconducting layered titania nanosheet (TNS) films was investigated here. Two types of intermediate films (i.e., TNS films containing methyl viologen (TNS/MV2+) and 2-ammoniumethanethiol (TNS/2-AET+)) were prepared. The two intermediate films were soaked in an aqueous tetrachloroauric(III) acid (HAuCl4) solution, whereby considerable amounts of Au(III) species were accommodated within the interlayer spaces of the TNS films. The two types of obtained films were then soaked in an aqueous sodium tetrahydroborate (NaBH4) solution, whereupon the color of the films immediately changed from colorless to purple, suggesting the formation of AuNPs within the TNS interlayer. When only TNS/MV2+ was used as the intermediate film, the color of the film gradually changed from metallic purple to dusty purple within 30 min, suggesting that aggregation of AuNPs had occurred. In contrast, this color change was suppressed by using the TNS/2-AET+ intermediate film, and the AuNPs were stabilized for over 4 months, as evidenced by the characteristic extinction (absorption and scattering) band from the AuNPs.

In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Here, we present a protocol for the in situ synthesis of gold nanoparticles (AuNPs) within the interlayer space of layered titanate films without the aggregation of AuNPs. No spectral change was observed even after 4 months. The synthesized material has expected applications in catalysis, photo-catalysis, and the development of cost-effective plasmonic devices.

在没有聚集的层状钛酸盐薄膜透明的层间金纳米粒子的原位合成

Combinations of metal oxide semiconductors and gold nanoparticles (AuNPs) have been investigated as new types of materials. The in situ synthesis of AuNPs ...

工程学

Liquid-cell Transmission Electron Microscopy for Tracking Self-assembly of Nanoparticles

Drying a nanoparticle dispersion is a versatile way to create self-assembled structures of nanoparticles, but the mechanism of this process is not fully understood. We have traced the trajectories of individual nanoparticles using liquid-cell transmission electron microscopy (TEM) to investigate the mechanism of the assembly process. Herein, we present the protocols used for liquid-cell TEM studies of the self-assembly mechanism. First, we introduce the detailed synthetic protocols used to produce uniformly sized platinum and lead selenide nanoparticles. Next, we present the microfabrication processes used to produce liquid cells with silicon nitride or silicon windows and then describe the loading and imaging procedures of the liquid-cell TEM technique. Several notes are included to provide helpful tips for the entire process, including how to manage the fragile cell windows. The individual motions of nanoparticles tracked by liquid-cell TEM revealed that changes in the solvent boundaries caused by evaporation affected the self-assembly process of nanoparticles. The solvent boundaries drove nanoparticles to primarily form amorphous aggregates, followed by flattening of the aggregates to produce a 2-dimensional (2D) self-assembled structure. These behaviors are also observed for different nanoparticle types and different liquid-cell compositions.

Here we introduce experimental protocols for the real-time observation of a self-assembly process using liquid-cell transmission electron microscopy.

用于跟踪纳米粒子自组装的液体细胞透射电子显微镜

Drying a nanoparticle dispersion is a versatile way to create self-assembled structures of nanoparticles, but the mechanism of this process is not fully ...

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

Platinum-nickel (Pt-Ni) nanowires were developed as fuel cell electrocatalysts, and were optimized for the performance and durability in the oxygen reduction reaction. Spontaneous galvanic displacement was used to deposit Pt layers onto Ni nanowire substrates. The synthesis approach produced catalysts with high specific activities and high Pt surface areas. Hydrogen annealing improved Pt and Ni mixing and specific activity. Acid leaching was used to preferentially remove Ni near the nanowire surface, and oxygen annealing was used to stabilize near-surface Ni, improving durability and minimizing Ni dissolution. These protocols detail the optimization of each post-synthesis processing step, including hydrogen annealing to 250 &#176;C, exposure to 0.1 M nitric acid, and oxygen annealing to 175 &#176;C. Through these steps, Pt-Ni nanowires produced increased activities more than an order of magnitude than Pt nanoparticles, while offering significant durability improvements. The presented protocols are based on Pt-Ni systems in the development of fuel cell catalysts. These techniques have also been used for a variety of metal combinations, and can be applied to develop catalysts for a number of electrochemical processes.

&#160; The protocol describes the synthesis and electrochemical testing of platinum-nickel nanowires. Nanowires were synthesized by the galvanic displacement of a nickel nanowire template. Post-synthesis processing, including hydrogen annealing, acid leaching, and oxygen annealing were used to optimize nanowire performance and durability in the oxygen reduction reaction.

铂镍纳米线的合成及减氧性能优化

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

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 ...

Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes

Ligands like amines are used in the colloidal synthesis approach to protect platinum nanoparticles (Pt NP&#39;s) from agglomeration. Normally, ligands like amines are removed by diverse pre-treatment procedures before use in heterogeneous catalysis as amines are considered as a catalyst poison. However, a possible beneficial influence of these surface modifiers on hydrogenation reactions, which is known from spectator species on metal surfaces, is often neglected.
Therefore, amine-stabilized Pt nanoparticles supported by titania (P25) were used without any pre-treatment in order to elucidate a possible influence of the ligand in liquid phase hydrogenation reactions. The catalytic activity of amine-stabilized Pt nanoparticles of two different sizes was investigated in a double-walled stirring tank reactor at 69 &#176;C to 130 &#176;C and 1 atm hydrogen pressure. The conversion of cyclohexene to cyclohexane was determined by gas chromatography (GC) and was compared to ligand-free Pt particles. All catalysts were checked before and after reaction by transmission electron spectroscopy (TEM) and X-ray photoelectron spectroscopy (XPS) for possible changes in size, shape, and ligand shell. The hydrogenation of cyclohexene in liquid phase revealed a higher conversion for amine-stabilized Pt nanoparticles on titania than the ligand-free particles. The hydrogenation of 5-methylfurfural (5-MF) was chosen for a further test reaction, since the hydrogenation of &#945;, &#946;-unsaturated aldehydes is more complex and exhibits various reaction paths. However, XPS and infrared spectroscopy (IR) proved that 5-MF acts as catalyst poison at the given reaction conditions.

This protocol shows a convenient method for comparing the catalytic properties of supported platinum catalysts, synthesized by deposition of nanosized colloids or by impregnation. The hydrogenation of cyclohexene serves as a model reaction to determine the catalytic activity of the catalysts.

烯烃和醛加氢过程中负载在二氧化钛上的胺稳定和无配体铂纳米颗粒的催化反应

Ligands like amines are used in the colloidal synthesis approach to protect platinum nanoparticles (Pt NP&#39;s) from agglomeration. Normally, ligands ...