Liu Jian, Cao Changyan, Liu Xiaozhi, Zheng Lirong, Yu Xiaohu, Zhang Qinghua, Gu Lin, Qi Ruilian, Song Weiguo
Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Angew Chem Int Ed Engl. 2021 Jul 5;60(28):15248-15253. doi: 10.1002/anie.202102647. Epub 2021 Jun 4.
Direct conversion of bulk metal or nanoparticles into metal single atoms under thermal pyrolysis conditions is a highly efficient and promising strategy to fabricate single-atom catalysts (SACs). Usually, nitrogen-doped carbon is used as the anchoring substrate to capture the migrating metal ion species at high temperatures, and stable isolated SACs with nitrogen coordination are formed during the process. Herein, we report unexpected oxygen-coordinated metal single-atom catalysts (Fe-, Co-, Ni-, Mn-SACs) with high loadings (above 10 wt %) through direct transformation of metal oxide nanoparticles (Fe-, Co-, Ni-, Mn-NPs) in an inert atmosphere at 750 °C for 2 h. The atomic dispersion of metal single atoms and their coordinated structures were confirmed by aberration-corrected scanning transmission electron microscopy and X-ray absorption fine structures. In addition, the dynamic process of nanoparticles to atoms was directly observed by in situ transmission electron microscopy. The as-prepared Fe SAC exhibited high activity and superior selectivity for catalytic oxidation of benzene to phenol with hydrogen peroxide.
在热解条件下将块状金属或纳米颗粒直接转化为金属单原子是制备单原子催化剂（SACs）的一种高效且有前景的策略。通常，氮掺杂碳用作锚定基质，在高温下捕获迁移的金属离子物种，并在此过程中形成具有氮配位的稳定孤立SACs。在此，我们报告了通过在惰性气氛中于750°C下将金属氧化物纳米颗粒（Fe-、Co-、Ni-、Mn-NPs）直接转化2小时，制备出具有高负载量（高于10 wt%）的意外的氧配位金属单原子催化剂（Fe-、Co-、Ni-、Mn-SACs）。通过像差校正扫描透射电子显微镜和X射线吸收精细结构证实了金属单原子的原子分散及其配位结构。此外，通过原位透射电子显微镜直接观察到了纳米颗粒到原子的动态过程。所制备的Fe SAC对用过氧化氢将苯催化氧化为苯酚表现出高活性和优异的选择性。
