High-throughput Computational Study Of The Influence Of Coordinatively Unsaturated Metal Sites On The Gas Separation Performance Of Mof Materials

With the vigorous development of society and economy,the energy crisis and the greenhouse effect have gradually become two major issues facing mankind.In order to reduce the dependence on traditional fossil fuels and the pressure on the environment,great efforts have been made so far to develop alternative clean energy sources and reduce the impact of the greenhouse effect.Hydrogen isotope separation is a key step to realize the controlled nuclear fusion,while CO2 capture is an effective way to reduce CO2 emissions.Although great progress has been achieved in these fields currently,the common problems existing in chemical separation processes,such as high energy consumption and low efficiency,need to be solved urgently.As a new type of member in the family of porous materials,metal-organic frameworks(MOFs)have been shown great application prospect in the field of adsorptive separation of gases because of their unique physicochemical characteristics.In particular,MOFs containing open metal sites(OMS;or called coordinatively unsaturated metal sites)have attracted wide attention of researchers.However,due to the large number of reported MOF materials and their theoretically infinite variety,it is difficult to systematically explore them solely using experimental methods.Therefore,a MOF database was firstly consructured which contains the meaterials featuring the paddle-wheel secondary inorganic structural unit,on the baisis of the Cambridge Structural Database(CSD).Then,a combination of quantum chemistry calculations and molecular simulations was adopted to systematically perform theoretical studies of the hydrogen isotope separation and CO2 capture performance of the collected MOFs with open cooper site(Cu-OMS).The main research work is outlined below:(1)The second-order M(?)ller-Plesset perturbation theory(MP2)combining with localized molecular orbital energy decomposition was used to study the interaction nature between isotopic molecules and Cu-OMS.Based on the quantum analysis results,a molecular force field was further developed to accurately describe the interactions between guest molecule and Cu-OMS,thus providing computational foundation for subsequent high-throughput materials screening.(2)Based on high-throughput molecular simulation methods,the D2/H2 quantum sieving performances of 930 Cu-MOFs in the constructed database were evaluated on a large scale.The best structural characteristics of high-perfromance materials were obtained through analysis of the property-performance relationships,together with further revealing the influences of the quantum effect and electrostatic effect on the separation behaviors of the materials.The results showed that the influence of quantum effect on the selectivity was significantly greater than that of the electrostatic interactions under cryogenic conditions,especially from the contribution of adsorbate-MOF interactions.Furthermore,some promising MOFs for hydrogen isotope separation were indentified.The obtained results could provide theoretical support for the design and synthesis of new high-performance materials toward isotope separation applications.(3)The CO2 capture performance of the MOFs in the database was also evaluated.By systematically investigating the property-activity relationships of these materials,optimal structural characteristics of ideal separation materials were proposed and some materials were also identified to potentially have promising applications for CO2 capture,which serves as a theoretical reference for the design and synthesis of high-performance materials for specific applications.