Influence of Crystal Facet and Phase of Titanium Dioxide on Ostwald Ripening of Supported Pt Nanoparticles from First-Principles Kinetics,The Journal of Physical Chemistry C

当前位置： X-MOL 学术 › J. Phys. Chem. C › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Influence of Crystal Facet and Phase of Titanium Dioxide on Ostwald Ripening of Supported Pt Nanoparticles from First-Principles Kinetics
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2019-04-18 , DOI: 10.1021/acs.jpcc.9b01942
Qixin Wan _{1,

2} , Sulei Hu _{3,

4} , Jiangnan Dai ₁ , Changqing Chen ₁ , Wei-Xue Li _{3,

4}

Affiliation

Metal oxide plays an important role on stability and catalytic performance of supported metal nanoparticles, but mechanistic understanding of structure sensitivity and optimization of the oxide supports remains elusive in heterogeneous catalysis. Taking Ostwald ripening of platinum nanoparticles supported on titanium dioxide (TiO₂) as an example, we reveal here a great structure sensitivity of oxide facets and crystal phases on sintering of supported metal nanoparticles through first-principles kinetic simulation. Total activation energies of the Pt ripening on various pristine TiO₂ surfaces of both anatase and rutile phases are calculated by density functional theory, and Ostwald ripening under isothermal condition and temperature programmed condition are simulated numerically. Calculated total activation energies are found inversely proportional to the corresponding oxide surface energies, and vary considerably from 1.76 to 3.56 eV. The Pt ripening rate on the pristine TiO₂ surfaces follows the order of r(001) ≈ a(001) ≫ a(100) ≈ r(101) > r(100) > a(101) ≈ r(110). For TiO₂ support exposing different facets, not only their intrinsic ripening rate but also their relative surface area determines the overall ripening kinetics and formation of transit bimodal particle size distribution. For pristine anatase TiO₂ exposing a(001) and a(101) facets, ripening starts on a(101) facets only after ripening on a(001) facets finishes due to their order of magnitude difference in ripening rate, resulting a step-wise increase of average particle size with ripening time. For pristine rutile TiO₂ exposing r(101) and r(110) facets, ripening could proceed simultaneously on both facets due to their modest difference in ripening rate, and the average particle size increases monotonically with ripening time. Compared to rutile TiO₂, anatase TiO₂ supports are less resistant to the metal nanoparticles ripening since a(001) facets with high ripening rate is likely to be exposed. The present work is compared to available experiments and the theoretical framework established could be expanded to various metal and oxide systems.

中文翻译：

晶面和二氧化钛相对第一性原理支撑的Pt纳米颗粒Ostwald熟化的影响

金属氧化物在负载型金属纳米颗粒的稳定性和催化性能上起着重要作用，但是在多相催化中，对结构敏感性的机械理解以及氧化物载体的优化仍然遥遥无期。以二氧化钛（TiO ₂）负载的铂纳米颗粒的奥斯特瓦尔德熟化为例，我们通过第一原理动力学模拟揭示了在烧结负载的金属纳米颗粒时氧化物面和晶相的结构敏感性。各种原始TiO ₂上Pt的总活化能利用密度泛函理论计算了锐钛矿相和金红石相的表面，并对等温和程序升温条件下的奥斯特瓦尔德熟化进行了数值模拟。发现计算出的总活化能与相应的氧化物表面能成反比，并且在1.76至3.56 eV之间变化很大。原始TiO ₂表面上的Pt成熟速率遵循r（001）≈a（001）≫ a（100）≈r（101）> r（100）> a（101）≈r（110）的顺序。对于暴露于不同面的TiO ₂载体，不仅其固有的熟化速率，而且其相对表面积决定了整体熟化动力学和过渡双峰粒度分布的形成。用于原始锐钛矿TiO ₂暴露a（001）和a（101）刻面后，仅在a（001）刻面完成了熟化之后，才开始在a（101）刻面上进行熟化，这是因为它们的熟化速率存在数量级差异，从而导致平均粒子的逐步增加大小与成熟时间。对于暴露于r（101）和r（110）面的原始金红石TiO _2而言，由于两个面的熟化速率差异不大，因此可以同时进行熟化，并且平均粒径随熟化时间而单调增加。与金红石型TiO ₂相比，锐钛矿型TiO ₂支撑物对金属纳米粒子的抗性较差，因为可能会暴露出具有高成熟速率的（001）小面。将目前的工作与可用的实验进行比较，并且可以将建立的理论框架扩展到各种金属和氧化物系统。

更新日期：2019-04-20

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南