The local electric field favours more than exposed nitrogen atoms on CO2 capture: a case study on the rht-type MOF platform

Two rht-type metal-organic frameworks (MOFs) based upon the tetrazolate moiety and pyrazolate moiety, respectively, have been investigated for carbon dioxide (CO2) adsorption and selective adsorption of CO2 over CH4, which shows that the rht-MOF featuring the pyrazolate moiety demonstrates superior performances compared to the rht-MOF based on the tetrazolate moiety. In spite of more exposed nitrogen atoms in the tetrazolate-based rht-MOF, the counter-intuitive observations of CO2 capture in the two rht-MOFs were interpreted by computational studies, which reveal that the local electric field favours more than the richness of exposed nitrogen atoms for the interactions with CO2 molecules.