MOF nano-crystals of ZIF-8 identified as ambient NO2 gas absorbent by using resonant micro-cantilever experiment

Based on resonant micro-cantilever measurements, the metal-organic framework (MOF) nano-crystal material of ZIF-8 is, for the first time, identified as an excellent absorbent to capture/fix the automobile exhaust of NO2 in real atmospheric air. By using MEMS resonant cantilever as material evaluation tool, the adsorbing properties of ZIF-8 to NO2 gas have been experimentally examined not only for qualitative judgement, but also for thermodynamic-level quantitative evaluation. Such identification can help to real the formation mechanism of NO2 associated PM2.5 particles and acid rain.

Introduction

Recently, capture and storage of gas molecules in atmospheric environment becomes an important research topic in many fields, especially in environmental protection [1]–[3]. An important goal of these researches aims to develop high-performance gas adsorbent. Featuring huge specific-surface-area, quite a lot of newly developed nano-materials, e.g., graphene and metalorganic frameworks (MOFs), are considered promising candidates for the application [4]. To comprehensively evaluate or optimize an adsorbing material, it is far from enough to simply observe its apparent parameters like surface area or porosity. Moreover, molecule adsorption in real atmospheric environment is inevitably influenced by ambient interfering factors like humidity. In case of lack of in-depth knowledge, the results of the laboratory can sometimes lead to feint information. For optimally designing an adsorption material, it would be better to look inside into the inherent nature of the material (i.e., the material ‘genome’).