Xin Pingyu, Li Jia, Xiong Yu, Wu Xi, Dong Juncai, Chen Wenxing, Wang Yu, Gu Lin, Luo Jun, Rong Hongpan, Chen Chen, Peng Qing, Wang Dingsheng, Li Yadong
Department of Chemistry, Tsinghua University, Beijing, 100084, China.
Institute of Advanced Materials, Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, China.
Angew Chem Int Ed Engl. 2018 Apr 16;57(17):4642-4646. doi: 10.1002/anie.201801103. Epub 2018 Mar 24.
The active species in supported metal catalysts are elusive to identify, and large quantities of inert species can cause significant waste. Herein, using a stoichiometrically precise synthetic method, we prepare atomically dispersed palladium-cerium oxide (Pd /CeO ) and hexapalladium cluster-cerium oxide (Pd /CeO ), as confirmed by spherical-aberration-corrected transmission electron microscopy and X-ray absorption fine structure spectroscopy. For aerobic alcohol oxidation, Pd /CeO shows extremely high catalytic activity with a TOF of 6739 h and satisfactory selectivity (almost 100 % for benzaldehyde), while Pd /CeO is inactive, indicating that the true active species are single Pd atoms. Theoretical simulations reveal that the bulkier Pd clusters hinder the interactions between hydroxy groups and the CeO surface, thus suppressing synergy of Pd-Ce perimeter.
负载型金属催化剂中的活性物种难以识别，并且大量的惰性物种会造成大量浪费。在此，我们使用化学计量精确的合成方法，制备出了原子级分散的钯 - 氧化铈（Pd/CeO₂）和六钯簇 - 氧化铈（Pd₆/CeO₂），这通过球差校正透射电子显微镜和X射线吸收精细结构光谱得到了证实。对于需氧醇氧化反应，Pd/CeO₂表现出极高的催化活性，其转化频率（TOF）为6739 h⁻¹，且选择性令人满意（对苯甲醛几乎为100%），而Pd₆/CeO₂则无活性，这表明真正的活性物种是单个钯原子。理论模拟表明，体积较大的钯簇阻碍了羟基与CeO₂表面之间的相互作用，从而抑制了Pd - Ce边界的协同作用。
