a.y. 获得了东京大学机械系统创新项目全球卓越中心的财政支持, 并得到了东京大学博士学位研究的东京都补助金。这项工作部分是由 jsp KAKENHI 资助的青年科学家 (B) (17K17718) 所支持的。

在使用化学品之前, 最好参考所有相关的材料安全数据表 (MSDS), 因为这些合成中的一些使用是高酸性和腐蚀性的。此外, 在这项工作中使用的一种聚合物 (聚丙烯酰胺) 可能含有致癌单体, 丙烯酰胺。使用个人防护设备 (安全眼镜, 手套, 实验室大衣, 全长长裤, 闭合脚趾鞋), 以防止伤害化学品或热。在进行交联过程后, 应将膜样品储存在黑暗条件下的水中, 以避免干燥和任何不必要的光化学反应的发生。
1. 聚甲醛/高分子复合膜的制备
注: 合成程序如下, 在文章中报告的海伦等。14, 除了 POM 的数量被改变。
<ol><li>前体聚乙烯醇 (PVA) 溶液的制备<ol>
<li>添加3克聚乙烯醇 1000 (完全水解) 和搅拌棒到50毫升瓶。</li>
		<li>给瓶子加27毫升水。</li>
		<li>在搅拌条件下, 将瓶子加热到70摄氏度, 以完全溶解所有聚乙烯醇微粒。</li>
	</ol>
</li>
	<li>前体聚丙烯酰胺 (PAM) 溶液的制备<ol>
<li>添加0.75 克聚丙烯酰胺 (见材料表) 和搅拌棒到50毫升瓶。</li>
		<li>给瓶子加29.25 毫升水。</li>
		<li>在搅拌条件下, 将瓶子加热到70摄氏度, 以完全溶解所有聚丙烯酰胺颗粒。</li>
	</ol>
</li>
	<li>聚甲醛和高分子混合物溶液的制备<ol>
<li>将2毫升 PVA 溶液和2毫升 PAM 溶液添加到50毫升瓶中。 注: 由于这些聚合物溶液具有高 viscocities, 所以准确测量其体积是必不可少的。</li>
		<li>添加一个三角形的搅拌杆和1克的 H3密码12O40到瓶子。 注意: H3密码12O40是一种高度酸性的材料, 应该储存在冰箱里。当使用它时, 用塑料材料而不是金属的。</li>
		<li>在剧烈搅拌条件下, 在水浴中加热瓶至70摄氏度, 在浸出70摄氏度后继续搅拌6小时。</li>
		<li>将玻璃衬底 (5 x 5 厘米2) 放在热板上 (约100°c), 并将溶液滴 750 ul 置于基体上。 注: 在滴入过程中应保持热解, 防止聚合物凝。</li>
		<li>要使样品干燥, 请在室温下将其保持在黑暗状态下过夜。</li>
	</ol>
</li>
	<li>膜样品交联工艺<ol>
<li>添加72毫升蒸馏水, 24 毫升丙酮, 2 毫升25% 戊二醛溶液, 和2毫升 HCl 到100毫升瓶。这种混合物称为交联试剂。</li>
		<li>把玻璃基体与样品在培养皿 (大约9.5 厘米直径) 和添加交联试剂, 直到膜完全浸入。</li>
		<li>30分钟后, 用蒸馏水代替交联溶液, 清洗一次。</li>
		<li>使用刮刀将膜从玻璃基板上剥离, 并将其贮存在冷水中。这种聚甲醛/高分子膜称为 pom/聚乙烯醇/PAM。 注: 如果膜用于下一过程 (与供方金属或 MnOx沉积反应), 则应省略剥离过程。</li>
		<li>利用聚甲醛/聚乙烯醇/PAM 的显微拉曼光谱和红外光谱测定膜13的化学结构。采用与参考相同的方法制备的聚乙烯醇/PAM (缺乏 POM) 样品的 FT 红外光谱。</li>
	</ol>
</li>
</ol>2. 聚甲醛/高分子膜与供体金属的反应 (Ce3 +和 Co2 +)
<ol><li>Ce3 +解决方案的准备工作。<ol>
<li>添加2.08 克 Ce (NO3)3 · 6H2O 和搅拌杆到50毫升瓶。</li>
		<li>将30毫升的水添加到瓶子中, 搅拌溶解所有 Ce (NO3)3。</li>
	</ol>
</li>
	<li>膜样品与 Ce3 +的反应<ol>
<li>将膜样品放入培养皿中 (大约9.5 厘米直径), 加入 Ce3 +溶液, 直到膜完全浸入。</li>
		<li>将培养皿放入预加热的烤箱中, 温度为80摄氏度, 为5小时。</li>
		<li>用蒸馏水代替 Ce3 +溶液, 清洗一次。</li>
		<li>储存在蒸馏水在黑暗的条件。</li>
	</ol>
</li>
	<li>Co2 +溶液的制备<ol>
<li>使用与 ce3 +相同的准备和反应程序, 除了使用1.14 克 CoCl2· 6H2O 而不是 ce (3)3 · 6H2o. 样品与 ce3 +和 Co2 +的反应是分别被称为 pom/聚乙烯醇/pam/Ce 和 pom/聚乙烯醇/pam/Co。</li>
		<li>研究了聚甲醛/聚乙烯醇/聚丙烯酰胺/铈和 pom/聚乙烯醇/pam/Co 的显微拉曼光谱, 以确定12O403-后的分子结构与供体金属离子13的反应。利用紫外-可见光谱研究了这些样品的光学特性。</li>
	</ol>
</li>
</ol>3. MnOx水氧化催化剂的沉积
注: 胶体 MnOx的制备和沉积程序遵循在佩雷斯-贝尼等。198915和高岛等201216, 分别。
<ol><li>胶体 MnOx溶液的制备<ol>
<li>加入39.4 毫克的 KMnO4和一个搅拌棒到30毫升烧杯。 注: 注意: KMnO4是一种高度氧化的材料;使用塑料匙, 而不是金属的。</li>
		<li>加入10毫升水的烧杯和搅拌完全溶解所有 KMnO4。</li>
		<li>添加50毫克 Na2S2O3· 5H2o 和椭圆形搅拌杆到500毫升的圆底烧瓶。</li>
		<li>加入20毫升水的烧瓶和搅拌完全溶解所有 Na2S2O3。</li>
		<li>在剧烈搅拌下加入10毫升的 KMnO4溶液到烧瓶中。 注: KMnO4溶液应缓慢添加, 以防止聚集 MnO2的形成。</li>
		<li>加入 KMnO4溶液后, 立即将470毫升蒸馏水添加到烧瓶中。</li>
		<li>保持搅拌超过2小时, 然后立即使用的解决方案为下一个过程 (喷涂)。</li>
	</ol>
</li>
	<li>在膜样品上喷涂 MnOx胶体溶液<ol>
<li>将薄膜样品放在热板上 (大约60°c), 用硅橡胶制成的口罩来确定用于沉积的区域。 注: 对于 MnOx催化剂的沉积, 应将膜样品放置在玻璃基体上。如果膜没有从基体剥离, 把它们放到热板上, 因为它们是。在沉积过程中保持膜表面湿润。该面膜还可以作为一个重量, 以防止膜起飞, 由于高气压从喷枪。</li>
		<li>添加300毫升的胶体 MnOx溶液到一个500毫升瓶连接到一个自动喷枪 (见材料表) 上方的热板和喷雾溶液到膜上。</li>
		<li>当瓶子里的体积减少时, 把剩下的胶体溶液添加到瓶子里。</li>
		<li>将样品储存在蒸馏水中, 在黑暗的条件。MnOx沉积后, 样品被称为 POM/聚乙烯醇/PAM/铈/MnOx或 POM/聚乙烯醇/PAM/Co/MnOx。</li>
		<li>利用光电测量法对聚甲醛/聚乙烯醇/PAM/Co/MnOx的可见光辐照下的电子传递特性进行了监测。为了进行光电实验, 在2O3 (ITO) 电极上制备了透明锡掺杂的膜试样。</li>
	</ol>
</li>
</ol>

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作者没有什么可透露的。

应用海伦等的交联方法是至关重要的。14开发一种独立的膜。本研究以聚醋酸乙烯为基聚合物, 对 H312O40进行聚集体, 防止自立膜的形成。然而, 当利用 Nafion 作为基聚合物制备膜时, 与 Ce3 +和 Co2 +的反应没有进展, 虽然已经实现了自立膜的制备。在本研究中, 为了保证整个膜的电子传递, 加载量被修改为 80 wt% H3密码12O40从 10 wt% hetelopolyanions 的工作中使用的海伦等。14。
显微拉曼光谱表明, 聚甲醛在聚合物基体中的分子结构在与 Ce3 +和 Co2 +的反应前后均有很高的保留, Keggin 的拉曼峰特性的保留证明了这一点。POM17的结构 (图 1a)。红外光谱分析证实 POM 成功地融入了高分子基质中。在与 POM 的反应中, 与聚合物的官能团相对应的振动峰值14被发现略有改变 (图 1b), 这表明了与聚合物形成氢键的过程。这种氢键形成也支持聚甲醛的分子分散与结晶 H3的12O40 , 没有聚合物基质时, 采用交联过程, 以避免聚集。
聚甲醛/聚乙烯醇/PAM 与 Ce3 +和 Co2 +的分步反应, 使供方金属的选择灵活, 这是一个非常重要的参数, 使理想的光化学多电子转移反应。与金属反应后, 样品的表面颜色从无色变淡黄色 (pom/pva/pam/Ce) 和粉红色 (pom/pva/pam/Co) (图 2)。紫外可见光谱显示了新的吸收在可见区域 (图 3a), 被分配到金属对金属电荷转移 (MMCT)。值得注意的是, 吸收波长取决于供体金属 (Ce3 +为420毫微米和 Co2 +为395毫微米; 吸收在530毫微米在 POM 或 PVAPAM 或 co 被分配到 Co2 +的 d d 转换), 表明吸收范围可以是通过修改捐赠金属来控制。
所构建的 MMCT 系统具有光激活 MnOx水氧化催化剂的能力。在2O3 (ITO) 电极上掺杂的光电, 通过对聚甲醛/pva/pam/铈/MnOx或 pom/聚乙烯醇/pam/Co/MnOx的测量, 证实了可见光辐照下的电子转移。光辐照增强了 pom/pva/聚丙烯酰胺/MnOx和 pom/聚乙烯醇/pam/Ce/MnOx的电流值, 而 pom/pva/pam/Co 和 pom/聚乙烯醇/pam/MnOx产生了一个微不足道的光电流 (图 3b)。可见光辐照的 POM/聚乙烯醇/PAM/co/MnOx诱导的 MMCT (coII → WVI) 和电子在12O403−站点向 ITO 电极传输之间的相互间跳跃之间的密码12O403−分子。此外, 在 Co 站点上生成的孔被转移到 MnOx。光电测量后进行的显微拉曼光谱表明, POM 结构保持不变, 不形成铈和 Co 氧化物, 表明样品稳定 (至少在本实验时间范围内)。聚甲醛/聚乙烯醇/聚丙烯酰胺/MnOx和 pom/聚乙烯醇/pam/铈/MnOx之间的光电流差别可以用 ce4 +/Ce3 +和 Co3 +/钴2 +氧化还原夫妇的氧化还原电位差来解释。由于 co3 +/co2 +夫妇拥有比 ce4 +/ce3 +夫妇更大的正氧化还原电位, 它有利于促进电子从 MnOx转移到 Co 站点。这一观察再次强调了对捐助金属进行灵活选择的重要性。此外, 在以前的一项研究中, 我们显示了受体站点的氧化还原电位可以通过使用其他类型的13的方法来控制, 从而扩大了该聚甲醛/高分子复合材料在反应场中的可用性, 以促进氧化和还原反应。
为了监测氧的演化反应, 采用了旋转环形圆盘电极电化学方法。该膜试样是在环形圆盘电极的圆盘部分制作的, 其中圆盘部分为玻碳, 环部为 Pt。在光电测量过程中, 在环部减少了 O2 , 观察到了还原电流。图 4显示了对光辐照反应的还原电流的增加。结果表明, 光照射下 MnOx表面的水氧化作用。在环部观察到的还原电流约为1μA, 相应的光电流约为2μA。由于 MnOx的水氧化是一个四电子过程, 而环部的 O2的还原是一个双电子过程, 因此光电流对水氧化的库仑效率几乎是100%。在实验条件下, 应用过电位为 460 mV。MnO2的电化学研究报告. 18在范围 0.5-0.7 V 到达当前密度 10 mA cm-2在 pH 值 = 13。虽然我们不能比较这些值, 仅仅是因为我们的膜系统中 MnOx的加载量和表面积是未知的, MnOx本身的加载方法和 OER 活动应该在今后的研究中得到改进。
本报告展示了一种在柔性高分子基质中采用交联工艺构造 polyoxometalate MMCT 单元的方法。这种 MMCT 的 photoresponsive 膜的局限性是可见光的弱吸收。由于 MMCT 单元中金属间的电子相互作用较弱, 因此, 氧桥式金属基电荷转移系统的吸收系数一般较小。然而, 与传统的半导体或有机分子光敏相比, 该系统在光的耐久性和氧化还原的调谐方面是有利的, 可以实现产品可分离的光化学系统。我们利用电极作为电子受体和 MnOx OER 催化剂作为孔受体;然而, 该膜系统也适用于其他催化系统, 其中各种氧化还原反应可以触发可见光照射。我们认为, 这一技术提供了一个新的战略, 以建立一个平台, 建设一个太阳能到化学转换系统。

利用人工光合作用或太阳能电池开发太阳能转换系统是必要的, 以便提供可替代的能源, 以改善全球气候和能源问题1、2、 3,4。光功能材料可以大致分为两组, 基于半导体的系统和基于有机分子的系统。虽然已经开发了许多不同的系统类型, 但仍需改进, 因为半导体系统缺乏精确的电荷转移控制, 而有机分子系统在光辐照。然而, 使用无机分子作为电荷转移单元的组成部分可以改善这些各自的问题。例如, 在介孔二氧化硅表面接枝的氧化桥型金属系统可以通过光辐照诱导金属-金属电荷转移 (MMCT), 并触发光化学氧化还原反应5,6,7,8,9。
我们的小组将单一原子系统扩展到一个多核系统, 利用 polyoxometalate (POM) 作为电子受体10,11,12, 并期望使用多核系统将是有利于诱导和控制多电子转移反应, 是能量转换中的一个重要概念。在本文所描述的协议中, 我们提出了用于准备基于 POM 的 MMCT 系统的详细方法, 它在聚合物矩阵中工作, 正如我们最近报告的13。膜型结构有利于阳极和阴极反应产物的分离。采用交联法, 即使具有高聚甲醛含量, 也能够形成自立膜。光电测量证明, 适当选择供体金属是触发目标的关键。POM/供体金属系统作为一种光敏剂在可见光照射下活化多电子转移催化剂。虽然这项工作利用 MnOx作为一个多电子转移催化剂的水氧化反应, 这一光功能系统也适用于其他类型的反应, 利用不同的, 捐助金属和催化剂。

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			<td height="42" style="height:42px;width:287px;">Poly(vinyl Alcohol) 1000, Completely Hydrolyzed</td>
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			<td style="width:119px;">162-16325</td>
			<td style="width:295px;"></td>
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			<td height="42" style="height:42px;width:287px;">Polyacrylamide, Mv 6,000,000</td>
			<td style="width:119px;">Polyaciences, Inc.</td>
			<td style="width:119px;">2806</td>
			<td>May contain carcinogenic monomer, acrylamide.</td>
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			<td height="21" style="height:21px;width:287px;">12 Tungsto(VI)phosphoric Acid n-Hydrate</td>
			<td style="width:119px;">Wako</td>
			<td style="width:119px;">164-02431</td>
			<td>Highly acidic</td>
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			<td style="width:119px;">Wako</td>
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			<td style="width:119px;">Wako</td>
			<td style="width:119px;">031-09732</td>
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			<td height="21" style="height:21px;width:287px;">Cobalt(II) Chloride Hexahydrate 99 + %(Ti)</td>
			<td style="width:119px;">Wako</td>
			<td style="width:119px;">036-03682</td>
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			<td height="21" style="height:21px;width:287px;">Pottasium Permanganate 99.3 + %(Ti)</td>
			<td style="width:119px;">Wako</td>
			<td style="width:119px;">167-04182</td>
			<td>Highly oxydative</td>
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			<td height="42" style="height:42px;width:287px;">Sodium Thiosulfate Pentahydrate 99 + %(Ti)</td>
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			<td height="21" style="height:21px;width:287px;">Automatic spray gun</td>
			<td style="width:119px;">Lumina</td>
			<td style="width:119px;">ST-6</td>
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preparation of polyoxometalate-based photo-responsive membranes for the photo-activation of manganese oxide catalysts

本文提出了一种用 polyoxotungstate (12O403-)、过渡金属离子 (Ce3 +或 Co2 +) 和有机聚合物制备电荷转移染色体的方法, 其目的是实现光激活。氧演化氧化锰催化剂, 是人工光合作用的重要组成部分。采用交联技术获得了高12O403含量的自立膜。采用红外光谱和显微拉曼光谱法, 对12O403-聚合物基体中的密码的加入和结构保留进行了验证, 并通过紫外-可见光谱研究了光学特性, 揭示了金属-金属电荷转移 (MMCT) 单元的成功构造。在 MnOx氧进化催化剂沉积后, 可见光照射下的光电流测量验证了顺序电荷转移、锰→ MMCT 单元→电极, 光电流强度与氧化还原反应一致。供方金属 (Ce 或 Co) 的潜力。该方法为制备具有光功能材料的催化剂和光子吸收部件的集成系统提供了一种新的策略。

通过红外光谱和显微拉曼光谱 (图 1) 证实了聚合物基体中 POM 结构的保留;观察了与 pom Keggin 结构相对应的振动峰, 发现聚合物的峰值由于与 pom 的氢键结合而转移。光谱学分析对于确定电荷转移单元的成功构造非常有用, 而且样品的表面颜色变化也证实了这一点 (图 2)。它也得到了紫外-可见光谱和光电测量 (图 3) 的证实, 因为当所有元件都完全对准时, 电荷转移就达到了。特别是光谱和光电结果证实了在光照射下定向电荷的转移, 从而支持了合成方法的有效性。利用旋转圆盘-环电极系统间接电化学法对 MnOx o2的生产进行了监测, 在光下可以观察到与 o2还原相对应的还原电流。辐照 (图 4)。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/58072/58072fig1.jpg"> 图 1: 微拉曼和红外光谱。(a)膜样品的显微拉曼光谱 (pom/pva/pam, 黑线) 和后与 Ce (NO3)3 (pom/pva/pam/Ce, 红线) 或 CoCl2 (pom/pva/pam/Co, 蓝线)。晶体 H3密码12O40的光谱也显示为参考 (暗黄色)。用20兆瓦强度的532纳米激光照射样品, 获得光谱。(b) 无甲醛样品 (黑线) 和 pom/聚乙烯醇/PAM (红线) 膜样品的 FT 红外光谱。将样品安装在装有 KBr 窗的自制透射式红外真空电池中, 通过氘 triglycine 硫酸盐检测器, 在室温下透射电模式获得了光谱。这一数字已被修改, 获得山口等201713, 版权2017美国化学协会的许可。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58072/58072fig1large.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/58072/58072fig2.jpg"> 图 2: 膜样品的图片.左: pom/聚乙烯醇/pam, 中心: pom/聚乙烯醇/pam/Ce, 和权利: pom/聚乙烯醇/pam/公司<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58072/58072fig2large.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/58072/58072fig3.jpg"> 图 3: 紫外-可见光漫反射光谱和 I t 曲线。(a)顶部: 聚甲醛/pva/聚丙烯酰胺膜样品前 (黑线) 和反应后与 Ce (NO3)3 (pom/聚乙烯醇/PAM/Ce, 红线) 的紫外可见光反射光谱。与 Ce (NO3)3反应后, 聚甲醛膜样品的频谱也显示为参考 (蓝线)。底部: 聚甲醛/pva/聚丙烯酰胺膜样品前 (黑线) 和后反应与 CoCl2 (pom/pva/pam/Co, 红线) 的紫外可见光谱。无甲醛膜样品 (PVA/PAM) 与 CoCl2无反应;因此, CoCl2的水溶液的紫外-可见光吸收光谱被用作参考 (蓝线)。插入是减法光谱 (在反应以后减去反应之前)。( b) It曲线为 (红线) POM/聚乙烯醇/PAM/Co/MnOx, (暗黄线) pom/聚乙烯醇/PAM/Ce/MnOx, (黑线) POM/聚乙烯醇/聚丙烯酰胺/Co, 和 (蓝线) POM/聚乙烯醇/PAM/MnOx样品在 ITO 电极上制备在20分钟的 Ar 冒泡后照射可见光。光源是一个 300 W 氙气灯, 装有 450 nm 截止过滤器, 以防止紫外线吸收。电解质是 0.1 M Na2如此4 (pH 值 10, 调整与 1 M 氢氧化钠) 和应用的潜力是 +1100 mV (vs 一个标准氢电极 [她])。这个数字已经从山口等201713, 版权2017美国化学学会修改。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58072/58072fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/58072/58072fig4.jpg"> 图 4: 我-t光辐照下旋转圆盘环电极环部的曲线。POM/聚乙烯醇/PAM/Co/MnOx是在磁盘部件上制造的。旋转速度为 1500 rpm, 磁盘和环电位保持在 1120 mv 和-280 mv 与她分别。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58072/58072fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Preparation of Polyoxometalate-based Photo-responsive Membranes for the Photo-activation of Manganese Oxide Catalysts at JoVE.com

Preparation of Polyoxometalate-based Photo-responsive Membranes for the Photo-activation of Manganese Oxide Catalysts

氧化锰催化剂光活化 Polyoxometalate 基光响应膜的制备

在这里, 我们提出了一个协议, 以准备电荷转移染色体基于 polyoxometalate/聚合物复合膜。

This paper presents a method to prepare charge-transfer chromophores using polyoxotungstate (PW12O403-), transition metal ions (Ce3+ or Co2+), and organic ...

preparation-polyoxometalate-based-photo-responsive-membranes-for

Nanyang Technological University

Research

JoVE Journal

Chemistry

7.6K 次观看.  The University of Tokyo. 在这里, 我们提出了一个协议, 以准备电荷转移染色体基于 polyoxometalate/聚合物复合膜。

视频: Preparation of Polyoxometalate-based Photo-responsive Membranes for the Photo-activation of Manganese Oxide Catalysts

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

原子定义模板复合氧化物薄膜的外延生长

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

科研

化学

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

对磷酸增强富集制备高度多孔配位聚合物涂层的孔聚合物石柱的

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

铱氧化物纳米颗粒对硒化镉硫化镉@纳米棒光化学氧化增长

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

Temperature-programmed Deoxygenation of Acetic Acid on Molybdenum Carbide Catalysts

Temperature programmed reaction (TPRxn) is a simple yet powerful tool for screening solid catalyst performance at a variety of conditions. A TPRxn system includes a reactor, furnace, gas and vapor sources, flow control, instrumentation to quantify reaction products (e.g., gas chromatograph), and instrumentation to monitor the reaction in real time (e.g., mass spectrometer). Here, we apply the TPRxn methodology to study molybdenum carbide catalysts for the deoxygenation of acetic acid, an important reaction among many in the upgrading/stabilization of biomass pyrolysis vapors. TPRxn is used to evaluate catalyst activity and selectivity and to test hypothetical reaction pathways (e.g., decarbonylation, ketonization, and hydrogenation). The results of the TPRxn study of acetic acid deoxygenation show that molybdenum carbide is an active catalyst for this reaction at temperatures above ca. 300 &#176;C and that the reaction favors deoxygenation (i.e., C-O bond-breaking) products at temperatures below ca. 400 &#176;C and decarbonylation (i.e., C-C bond-breaking) products at temperatures above ca. 400 &#176;C.

Presented here is a protocol for the operation of a micro-scale temperature-programmed reactor for evaluating the catalytic performance of molybdenum carbide during acetic acid deoxygenation.

对碳化钼催化合成乙酸的程序升温脱氧

Temperature programmed reaction (TPRxn) is a simple yet powerful tool for screening solid catalyst performance at a variety of conditions. A TPRxn system ...

Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are demonstrated here. The catalyst forms a substitutional solid solution structure, with a small and uniform particle size around 2 nm. This is realized by careful control over the impregnation, calcination, and reduction steps during catalyst preparation and is identified by advanced in situ synchrotron techniques. The catalyst propane dehydrogenation performance continuously improves with increasing Cu:Pt atomic ratio.

A convenient method for the synthesis of 2 nm supported bimetallic nanoparticle Pt-Cu catalysts for propane dehydrogenation is reported here. In situ synchrotron X-ray techniques allow for the determination of the catalyst structure, which is typically unobtainable using laboratory instruments.

用于丙烷脱氢的负载型Pt-Cu固溶体纳米粒子催化剂的合成与测试

A convenient method for the synthesis of bimetallic Pt-Cu catalysts and performance tests for propane dehydrogenation and characterization are ...

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, their high cost production and/or incompatibility with microfabrication technologies, due to the use of pre-deposited catalyst-seeds and/or high processing temperatures exceeding 900 &#176;C, represent a drawback for a widespread use of these methods. Here, however, we report the synthesis of ZnO rods via a non-catalyzed vapor-solid mechanism enabled by using an aerosol-assisted chemical vapor deposition (CVD) method at 400 &#176;C with zinc chloride (ZnCl2) as the precursor and ethanol as the carrier solvent. This method provides both single-step formation of ZnO rods and the possibility of their direct integration with various substrate types, including silicon, silicon-based micromachined platforms, quartz, or high heat resistant polymers. This potentially facilitates the use of this method at a large-scale, due to its compatibility with state-of-the-art microfabrication processes for device manufacture. This report also describes the properties of these structures (e.g., morphology, crystalline phase, optical band gap, chemical composition, electrical resistance) and validates its gas sensing functionality towards carbon monoxide.

Columnar zinc oxide structures in the form of rods are synthesized via aerosol-assisted chemical vapor deposition without the use of pre-deposited catalyst-seed particles. This method is scalable and compatible with various substrates based on either silicon, quartz or polymers.

金属氧化物结构的气溶胶辅助化学气相沉积: 氧化锌棒

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, ...

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of NixNb1-xO nanoparticles with different atomic compositions (x = 0.03, 0.08, 0.15, and 0.20) have been prepared by chemical precipitation. These NixNb1-xO catalysts are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The study revealed the sponge-like and fold-like appearance of Ni0.97Nb0.03O and Ni0.92Nb0.08O on the NiO surface, and the larger surface area of these NixNb1-xO catalysts, compared with the bulk NiO. Maximum surface area of 173 m2/g can be obtained for Ni0.92Nb0.08O catalysts. In addition, the catalytic hydroconversion of lignin-derived compounds using the synthesized Ni0.92Nb0.08O catalysts have been investigated.

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

A protocol for the synthesis of sponge-like and fold-like Ni1-xNbxO nanoparticles by chemical precipitation is presented.

化学沉淀法合成铌2O5改性高比表面积镍催化剂

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of ...

Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

We report the synthesis of thin, highly intergrown, polycrystalline metal-organic framework (MOF) membranes on a wide range of unmodified porous and non-porous supports (polymer, ceramic, metal, carbon, and graphene). We developed a novel crystallization technique, which is termed the ENACT approach: the electrophoretic nuclei assembly for the crystallization of highly intergrown thin films (ENACT). This approach allows for a high density of heterogeneous nucleation of MOFs on a chosen substrate via the electrophoretic deposition (EPD) directly from the precursor sol. The growth of well-packed MOF nuclei leads to a highly intergrown polycrystalline MOF film. We show that this simple approach can be used for the synthesis of thin, intergrown zeolite imidazole framework (ZIF)-7 and ZIF-8 films. The resulting 500 nm-thick ZIF-8 membranes show a considerably high H2 permeance (8.3 x 10-6 mol m-2 s-1 Pa-1) and ideal gas selectivities (7.3 for H2/CO2, 15.5 for H2/N2, 16.2 for H2/CH4, and 2655 for H2/C3H8). An attractive performance for C3H6/C3H8 separation is also achieved (a C3H6 permeance of 9.9 x 10-8 mol m-2 s-1 Pa-1 and a C3H6/C3H8 ideal selectivity of 31.6 at 25 &#176;C). Overall, the ENACT process, owing to its simplicity, can be extended to synthesize intergrown thin films of a wide range of nanoporous crystalline materials.

A simple, reproducible, and versatile approach for the synthesis of intergrown, polycrystalline metal-organic framework membranes on a wide range of unmodified porous and non-porous supports is presented.

超薄高性能金属-有机骨架膜的电泳结晶

We report the synthesis of thin, highly intergrown, polycrystalline metal-organic framework (MOF) membranes on a wide range of unmodified porous and ...

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared according to the methodology developed by surface organometallic chemistry (SOMC). In this framework, catalytic cycles can be determined by isolating crucial intermediates. All air-sensitive materials are handled under inert atmosphere (using gloveboxes or a Schlenk line) or high vacuum lines (HVLs, &#60;10-5 mbar). The preparation of SiO2-700 (silica dehydroxylated at 700 &#176;C) and subsequent applications (the grafting of complexes and catalytic runs) requires the use of HVLs and double-Schlenk techniques. Several well-known characterization methods are used, such as Fourier-transform infrared spectroscopy (FTIR), elemental microanalysis, solid-state nuclear magnetic resonance spectroscopy (SSNMR), and state-of-the-art dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP-SENS). FTIR and elemental microanalysis permit scientists to establish the grafting and its stoichiometry. 1H and 13C SSNMR allows the structural determination of the hydrocarbon ligands coordination sphere. DNP SENS is an emerging powerful technique in solid characterization for the detection of poorly sensitive nuclei (15N, in our case). SiO2-700 is treated with about one equivalent of the metal precursor compared to the amount of surface silanol (0.30 mmol&#183;g-1) in pentane at room temperature. Then, volatiles are removed, and the powder samples are dried under dynamic high vacuum to afford the desired materials [(&#8801;Si-O-)Hf(&#951;2&#960;-MeNCH2)(&#951;1-NMe2)(&#951;1-HNMe2)]. After a thermal treatment under high vacuum, the grafted complex is converted into metal imido silica complex [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)]. [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] effectively promotes the metathesis of imines, using the combination of two imine substrates, N-(4-phenylbenzylidene)benzylamine, or N-(4-fluorobenzylidene)-4-fluoroaniline, with N-benzylidenetert-butylamine as substrates. A significantly lower conversion is observed with the blank runs; thus, the presence of the imido group in [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is correlated to the catalytic performance.

A new group IV metal catalyst for imine metathesis is prepared by grafting amine metal complex onto dehydroxylated silica. Surface metal fragments are characterized using FT-IR, elemental microanalysis, and solid-state NMR spectroscopy. Further dynamic nuclear polarization surface enhanced NMR spectroscopy experiments complement the determination of the coordination sphere.

利用表面有机金属化学方法，利用硅支持的催化剂进行Imine金属分析

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared ...

Tuning the Acidity of Pt/ CNTs Catalysts for Hydrodeoxygenation of Diphenyl Ether

We herein present a method for the synthesis of HNbWO6, HNbMoO6, HTaWO6 solid acid nanosheet modified Pt/CNTs. By varying the weight of various solid acid nanosheets, a series of Pt/xHMNO6/CNTs with different solid acid compositions (x = 5, 20 wt%; M = Nb, Ta; N = Mo, W) have been prepared by carbon nanotube pretreatment, protonic exchange, solid acid exfoliation, aggregation and finally Pt particles impregnation. The Pt/xHMNO6/CNTs are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and NH3-temperature programmed desorption. The study revealed that HNbWO6 nanosheets were attached on CNTs, with some edges of the nanosheets being bent in shape. The acid strength of the supported Pt catalysts increases in the following order: Pt/CNTs &#60; Pt/5HNbWO6/CNTs &#60; Pt/20HNbMoO6/CNTs &#60; Pt/20HNbWO6/CNTs &#60; Pt/20HTaWO6/CNTs. In addition, the catalytic hydroconversion of lignin-derived model compound: diphenyl ether using the synthesized Pt/20HNbWO6 catalyst has been investigated.

A protocol for the synthesis of HNbWO6, HNbMoO6, HTaWO6 solid acid nanosheet modified Pt/CNTs is presented.

调整二苯醚氢氧化的Pt/CNT催化剂的酸度

We herein present a method for the synthesis of HNbWO6, HNbMoO6, HTaWO6 solid acid nanosheet modified Pt/CNTs. By varying the weight of various solid acid ...