Single-atom catalysts(SACs) with well-defined and specific single-atom dispersion on supports offer great potential for achieving both high catalytic activity and selectivity. Covalent organic frameworks(COFs) with ta...Single-atom catalysts(SACs) with well-defined and specific single-atom dispersion on supports offer great potential for achieving both high catalytic activity and selectivity. Covalent organic frameworks(COFs) with tailormade crystalline structures and designable atomic composition is a class of promising supports for SACs. Herein, we have studied the binding sites and stability of Pd single atoms(SAs)dispersed on triazine COF(Pd1/trzn-COF) and the reaction mechanism of CO oxidation using the density functional theory(DFT). By evaluating different adsorption sites, including the nucleophilic sp2C atoms, heteroatoms and the conjugated π-electrons of aromatic ring and triazine, it is found that Pd SAs can stably combine with trzn-COF with a binding energy around-5.0 eV, and there are two co-existing dynamic Pd1/trzn-COFs due to the adjacent binding sites on trzn-COF. The reaction activities of CO oxidation on Pd1/trzn-COF can be regulated by the anion–π interaction between a +δ phenyl center and the related-δ moieties as well as the electron-withdrawing feature of imine in the specific complexes. The Pd1/trzn-COF catalyst is found to have a high catalytic activity for CO oxidation via a plausible tri-molecular Eley-Rideal(TER) reaction mechanism. This work provides insights into the d–π interaction between Pd SAs and trznCOF, and helps to better understand and design new SACs supported on COF nanomaterials.展开更多
基金supported by the National Natural Science Foundation of China (22033005,21590792 and 21763006)Guangdong Provincial Key Laboratory of Catalysis (2020B121201002)。
文摘Single-atom catalysts(SACs) with well-defined and specific single-atom dispersion on supports offer great potential for achieving both high catalytic activity and selectivity. Covalent organic frameworks(COFs) with tailormade crystalline structures and designable atomic composition is a class of promising supports for SACs. Herein, we have studied the binding sites and stability of Pd single atoms(SAs)dispersed on triazine COF(Pd1/trzn-COF) and the reaction mechanism of CO oxidation using the density functional theory(DFT). By evaluating different adsorption sites, including the nucleophilic sp2C atoms, heteroatoms and the conjugated π-electrons of aromatic ring and triazine, it is found that Pd SAs can stably combine with trzn-COF with a binding energy around-5.0 eV, and there are two co-existing dynamic Pd1/trzn-COFs due to the adjacent binding sites on trzn-COF. The reaction activities of CO oxidation on Pd1/trzn-COF can be regulated by the anion–π interaction between a +δ phenyl center and the related-δ moieties as well as the electron-withdrawing feature of imine in the specific complexes. The Pd1/trzn-COF catalyst is found to have a high catalytic activity for CO oxidation via a plausible tri-molecular Eley-Rideal(TER) reaction mechanism. This work provides insights into the d–π interaction between Pd SAs and trznCOF, and helps to better understand and design new SACs supported on COF nanomaterials.
