https://www.sciencedirect.com/science/article/pii/S0926337321000758

Highlights

• •Ultrathin Al2O3 nanosheet was synthesized by a phosphate-assisted dynamic hydrothermal method.

• •Al2O3 nanosheet presented superior thermal stability and retained θ phase at 1200 °C.

• •An intercalation-swelling-exfoliation pathway accompanied by phosphate induced dissolution-growth was proposed.

• •Pd/Al2O3 nanosheet revealed high activity of propane combustion and resistance to sintering.

• •Re-dispersion of Pd and SMSI via high-temperature treatment was observed.

Abstract

Two-dimensional γ-Al2O3 nanosheet with rich pentacoordinate Al3+ sites which can nicely stabilize noble metals via strong interactions between metal and support has been focused. However, the synthesis of ultrathin and highly thermal-stable Al2O3 is challenging. Herein, we report an effective approach to synthesize ultrathin Al2O3 nanosheets with regular leaf-like architecture as well as high thermal-stability. A novel intercalation-swelling-exfoliation pathway was proposed to elucidate the formation of ultrathin sheet-like structure and then its morphology/thickness could be further adjusted via a dissolution-growth induced by phosphate. Meanwhile, the presence of phosphate further enhanced thermal stability of Al2O3 nanosheets due to the occupation or depletion of high-reactive sites and surface hydroxy groups. Subsequently, the thermally stable γ-Al2O3 nanosheets with moderate anchoring sites was used as a support of Pd and investigated for catalytic combustion of propane. The Pd/Al2O3 nanosheet exhibited a superior catalytic activity for propane combustion and the complete conversion was below 300 °C, more importantly, the outstanding resistance to high temperature (1000 °C) was observed, which was ascribed to the re-dispersion of Pd particles and the occurrence of strong metal-support interaction (SMSI) at high temperature.

特别感谢瞻望成教授的两个学生（吴青青、颜娇榕）的贡献

本文的主要“内容”来源于多年前的一篇文章中参比样品的制备，经过后续进一步发展而成

Qiguang Dai*, Qin Zhu; Yang Lou; Xingyi Wang*, Role of Brønsted Acid Site during Catalytic Combustion of Methane over PdO/ZSM-5: Dominant or Negligible？, Journal of Catalysis, 357, 2018, 29–40.

https://www.sciencedirect.com/science/article/pii/S002195171730355X

多年前，2017，在制备ZSM-5分子筛的对照样品SiO2和Al2O3，按照分子筛的制备方法，得到SiO2样品理所当然是纯Si-ZSM-5，但是对于纯氧化铝样品发现有点特别，表现出纳米片形貌。在文章发表之后，就做了初步的实验，进一步验证了氧化铝纳米片确实能够合成且可以调控，后续申请了专利，也顺利授权。由于平时比较忙也没学生，这个工作就放下了。

后来向詹教授“借”了个学生，把氧化铝纳米片合成的工作捡了起来，经过进一步的完善、扩展（预期后续还能成文两篇小文章），成文为本文：优化制备方法、考察更多细节、探究了合成机理、以及热稳定性方面带来的好处，负载贵金属考察丙烷催化燃烧活性、进一步确认课题组前期发现的贵金属高温再分散现象等等工作

关于本文的一点感想：有很多“成果”来自于意外，实验人的细心程度、洞察力尤为重要，导师经验丰富但如果不在“一线”很多可能有意义的东西都会被无经验的学生白白放过

本人有很多材料的合成都来自意外，后续将逐渐成文（目前至少有4种材料，有时间后都要整理出来）