Two-Step Carbothermal Welding To Access Atomically Dispersed Pd1 on Three-Dimensional Zirconia Nanonet for Direct Indole Synthesis

Yafei Zhao; Huang Zhou; Wenxing Chen; Yujing Tong; Chao Zhao; Yue Lin; Zheng Jiang; Qingwei Zhang; Zhenggang Xue; Weng-Chon Cheong; Benjin Jin; Fangyao Zhou; Wenyu Wang; Min Chen; Xun Hong; Juncai Dong; Shiqiang Wei; Yadong Li; Yuen Wu

doi:10.1021/jacs.9b03182

Two-Step Carbothermal Welding To Access Atomically Dispersed Pd₁ on Three-Dimensional Zirconia Nanonet for Direct Indole Synthesis

J Am Chem Soc. 2019 Jul 10;141(27):10590-10594. doi: 10.1021/jacs.9b03182. Epub 2019 Jun 17.

Authors

Yafei Zhao¹, Huang Zhou¹, Wenxing Chen², Yujing Tong¹, Chao Zhao¹, Yue Lin¹, Zheng Jiang³, Qingwei Zhang¹, Zhenggang Xue¹, Weng-Chon Cheong⁴, Benjin Jin¹, Fangyao Zhou¹, Wenyu Wang¹, Min Chen¹, Xun Hong¹, Juncai Dong⁵, Shiqiang Wei⁶, Yadong Li⁴, Yuen Wu¹

Affiliations

¹ Department of Chemistry, Hefei National Laboratory for Physical Sciences at the Microscale, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials) , University of Science and Technology of China , Hefei 230026 , China.
² Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, School of Materials Science and Engineering , Beijing Institute of Technology , Beijing 100081 , P. R. China.
³ National Synchrotron Radiation Laboratory , Shanghai Institute of Applied Physics , Shanghai 201800 , P. R. China.
⁴ Department of Chemistry , Tsinghua University , Beijing 100084 , P. R. China.
⁵ Institute of Physics, Chinese Academy of Sciences , Beijing 100190 , P. R. China.
⁶ National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230026 , China.

PMID: 31188590
DOI: 10.1021/jacs.9b03182

Abstract

Herein, we report a novel carbothermal welding strategy to prepare atomically dispersed Pd sites anchored on a three-dimensional (3D) ZrO₂ nanonet (Pd₁@ZrO₂) via two-step pyrolysis, which were evolved from isolated Pd sites anchored on linker-derived nitrogen-doped carbon (Pd₁@NC/ZrO₂). First, the NH₂-H₂BDC linkers and Zr₆-based [Zr⁶(μ₃-O)₄(μ₃-OH)₄]¹²⁺ nodes of UiO-66-NH₂ were transformed into amorphous N-doped carbon skeletons (NC) and ZrO₂ nanoclusters under an argon atmosphere, respectively. The NC supports can simultaneously reduce and anchor the Pd sites, forming isolated Pd₁-N/C sites. Then, switching the argon to air, the carbonaceous skeletons are gasified and the ZrO₂ nanoclusters are welded into a rigid and porous nanonet. Moreover, the reductive carbon will result in abundant oxygen (O*) defects, which could help to capture the migratory Pd₁ species, leaving a sintering-resistant Pd₁@ZrO₂ catalyst via atom trapping. This Pd₁@ZrO₂ nanonet can act as a semi-homogeneous catalyst to boost the direct synthesis of indole through hydrogenation and intramolecular condensation processes, with an excellent turnover frequency (1109.2 h^-1) and 94% selectivity.