Crystal size dependence on gate opening phenomenon of ZIF-8

Capture and sequestration of anthropogenic CO2 is a grand challenge of 21st Century. Metal-organic frameworks, in particular, Zeolitic imidazolate frameworks (ZIFs), wherein metals are bridged to organic linkers are a new class of materials showing extraordinary capability for CO2 capture. It has been shown that a dramatic increase in gas adsorption occurs at a critical pressure in ZIF-8 due to interaction of adsorbate molecule and this phenomenon is named as “gate opening”. Only limited work is available on the effect of crystal size on the properties of ZIF. Recent studies have shown that structural flexibility in ZIF-8 goes beyond gas-induced gate-opening effect to understand the adsorption behavior. The present proposal aims to study crystal dependent adsorption behavior of CO2 in ZIF-8 to elucidate adsorption mechanism using inelastic neutron scattering at TOSCA.

人为源二氧化碳的捕获与封存，是21世纪亟待攻克的重大挑战。金属有机框架（Metal-Organic Frameworks, MOFs）中，沸石咪唑酯骨架（Zeolitic Imidazolate Frameworks, ZIFs）极具研究价值，这类材料由金属节点与有机配体桥联构筑，是一类展现出优异二氧化碳捕获性能的新型功能材料。已有研究证实，ZIF-8材料在临界压力下会因吸附质分子的相互作用发生气体吸附量的陡增，该现象被称为‘门开效应（gate opening）’。目前针对晶体尺寸对ZIF材料性能影响的研究仍较为匮乏。近期研究表明，ZIF-8的结构柔性机制远超气体诱导门开效应的范畴，可为阐释其吸附行为提供更全面的理论支撑。本研究旨在探究ZIF-8材料中二氧化碳吸附行为的晶体尺寸依赖性，并借助TOSCA谱仪的非弹性中子散射（inelastic neutron scattering）技术阐明其吸附机理。