CAJ | 학술논문

金属-有机骨架材料（metal-organic frameworks, MOFs）是一类新型纳米多孔功能材料。由于其独特的结构特征，在催化方面展现出潜在的应用价值。采用分子模拟结合密度泛函理论的计算方法系统地研究了ZIF-8在负载金属Pd、Ag、Pt、Au后的催化活性。结果表明，金属与材料之间主要有3种作用方式，其中以“碳-金属-碳”(C-M-C)形式最为稳定。并且对于同一种方式，ZIF-8负载金属后的稳定性顺序为：Pd > Ag > Pt > Au。同时，利用CO作为探针分子，系统地研究了负载金属后ZIF-8的催化活性，发现这些金属原子的Lewis酸性强弱与其电子接受能力有关，其催化活性顺序为：Pd > Pt > Ag > Au。这为研究利用MOF材料负载金属用于催化提供了参考信息。carbon-metal-carbon (C-M-C), metal-carbon (M-C) and metal-bond (M-bond) modes, where the first type was the most stable one. For the same interaction type, the order of the stability of ZIF-8 with different metals was： Pd > Ag > Pt > Au. At the same time, the catalytic activity of the metal-supported materials was also investigated using CO as probe molecule. The analysis of the Mulliken population and the electrostatic potential distributions of metals indicated that metal particles were the Lewis acid sites which were related to their capabilities of accepting an electron. The order of their catalytic activities was： Pd > Pt > Ag > Au. The results obtained in this work may provide useful information for the catalytic application of MOFs loaded with metals.
금속-유궤골가재료（metal-organic frameworks, MOFs）시일류신형납미다공공능재료。유우기독특적결구특정，재최화방면전현출잠재적응용개치。채용분자모의결합밀도범함이론적계산방법계통지연구료ZIF-8재부재금속Pd、Ag、Pt、Au후적최화활성。결과표명，금속여재료지간주요유3충작용방식，기중이“탄-금속-탄”(C-M-C)형식최위은정。병차대우동일충방식，ZIF-8부재금속후적은정성순서위：Pd > Ag > Pt > Au。동시，이용CO작위탐침분자，계통지연구료부재금속후ZIF-8적최화활성，발현저사금속원자적Lewis산성강약여기전자접수능력유관，기최화활성순서위：Pd > Pt > Ag > Au。저위연구이용MOF재료부재금속용우최화제공료삼고신식。carbon-metal-carbon (C-M-C), metal-carbon (M-C) and metal-bond (M-bond) modes, where the first type was the most stable one. For the same interaction type, the order of the stability of ZIF-8 with different metals was： Pd > Ag > Pt > Au. At the same time, the catalytic activity of the metal-supported materials was also investigated using CO as probe molecule. The analysis of the Mulliken population and the electrostatic potential distributions of metals indicated that metal particles were the Lewis acid sites which were related to their capabilities of accepting an electron. The order of their catalytic activities was： Pd > Pt > Ag > Au. The results obtained in this work may provide useful information for the catalytic application of MOFs loaded with metals.
Metal-organic frameworks (MOFs) are a new family of nanoporous functional materials that have shown potential applications in catalysis, due to their unique structural features. In this work, a combination of molecular simulation and density functional theory (DFT) calculation were employed to investigate the catalytic properties of metal-supported ZIF-8 with different metals (Pd, Ag, Pt and Au). First, the radial distribution function between these metal particles and the different atoms in ZIF-8 was analyzed from Monte Carlo (MC) and molecular dynamics (MD) simulations in order to determine the possible locations of the metal particles. Then, DFT calculations were performed at the generalized gradient corrected approximation (GGA) level with PW91 functional and the double numerical plus polarization (DNP) basis set. The binding energy was calculated to evaluate the relative stability of the metal particles (Pd, Ag, Pt and Au) in each site of the framework. The results showed that there were three types of interaction modes between the metals and the framework carbon-metal-carbon (C-M-C), metal-carbon (M-C) and metal-bond (M-bond) modes, where the first type was the most stable one. For the same interaction type, the order of the stability of ZIF-8 with different metals was: Pd > Ag > Pt > Au. At the same time, the catalytic activity of the metal-supported materials was also investigated using CO as probe molecule. The analysis of the Mulliken population and the electrostatic potential distributions of metals indicated that metal particles were the Lewis acid sites which were related to their capabilities of accepting an electron. The order of their catalytic activities was: Pd > Pt > Ag > Au. The results obtained in this work may provide useful information for the catalytic application of MOFs loaded with metals.