Atomic-Scale Structure of Mesoporous Silica-Encapsulated Pt and PtSn Nanoparticles Revealed by Dynamic Nuclear Polarization-Enhanced 29 Si MAS NMR Spectroscopy
Atomic-Scale Structure of Mesoporous Silica-Encapsulated Pt and PtSn Nanoparticles Revealed by Dynamic Nuclear Polarization-Enhanced 29 Si MAS NMR Spectroscopy
复制标题
动态核极化增强 29 Si MAS NMR 光谱揭示介孔二氧化硅封装的 Pt 和 PtSn 纳米粒子的原子尺度结构
DOI：
10.1021/acs.jpcc.9b01782
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Bowers, Clifford Russell
中科院分区：
文献类型：
--
作者：
Zhao, Evan Wenbo;Maligal-Ganesh, Raghu;Mentink-Vigier, Frederic;Zhao, Tommy Yunpu;Du, Yong;Pei, Yuchen;Huang, Wenyu;Bowers, Clifford Russell
介孔二氧化硅包覆的Pt（Pt@mSiO2）和PtSn（PtSn@mSiO2）纳米颗粒（NPs）是一类具有均匀粒径、增强的催化性能和上级热稳定性的新型多相催化剂的代表。在瓶中运输合成中，PtSn@mSiO2金属间纳米颗粒衍生自Pt@mSiO2晶种，其中mSiO 2壳是通过正硅酸四乙酯围绕十四烷基三甲基溴化铵模板（用于模板化MCM-41的表面活性剂）聚合形成的。Sn到Pt@mSiO2种子中的掺入通过mSiO 2壳的化学蚀刻来调节。这种蚀刻对mSiO 2的原子尺度结构的影响以前没有被研究过，也没有MCM-41的结构相似性的程度。在这里，四元Q2，Q3，和Q4网站对应于式Si（O 1/2）2（OH）2，Si（O 1/2）3（OH）1，和Si（O 1/2）4中的MCM-41和介孔二氧化硅的Pt@mSiO2和PtSn@mSiO2纳米粒子进行了鉴定和定量的常规和动态核极化（DNP）增强29 Si魔角自旋核磁共振。通过DNP增强的二维29 Si-29 Si相关光谱揭示了−Si-O-Si-网络的连接性。
Mesoporous silica-encapsulated Pt (Pt@mSiO2) and PtSn (PtSn@mSiO2) nanoparticles (NPs) are representatives of a novel class of heterogeneous catalysts with uniform particle size, enhanced catalytic properties, and superior thermal stability. In the ship-in-a-bottle synthesis, PtSn@mSiO2intermetallic NPs are derived from Pt@mSiO2seeds where the mSiO2shell is formed by polymerization of tetraethyl orthosilicate around a tetradecyltrimethylammonium bromide template, a surfactant used to template MCM-41. Incorporation of Sn into the Pt@mSiO2seeds is accommodated by chemical etching of the mSiO2shell. The effect of this etching on the atomic-scale structure of mSiO2has not been previously examined, nor has the extent of the structural similarity to MCM-41. Here, the quaternary Q2, Q3, and Q4sites corresponding to formulas Si(O1/2)2(OH)2, Si(O1/2)3(OH)1, and Si(O1/2)4in MCM-41 and the mesoporous silica of Pt@mSiO2and PtSn@mSiO2NPs were identified and quantified by conventional and dynamic nuclear polarization (DNP)-enhanced29Si magic angle spinning nuclear magnetic resonance. The connectivity of the −Si–O–Si– network was revealed by DNP-enhanced two-dimensional29Si–29Si correlation spectroscopy.