Catalyzed activation of CO2 by a Lewis-base site in W–Cu–BTC hybrid metal organic frameworks

Abstract

A metal–organic framework (MOF)-based catalyst W–Cu–BTC is designed by hybridizing highly active W ions into Cu₃(BTC)₂(H₂O)₃ (also known as Cu–BTC or HKUST-1, BTC = 1,3,5-tricarboxylate benzene) frameworks based on density functional (DFT) calculations. We show that the hybrid W–Cu node plays a pivotal role in activating CO₂ according to frontier molecular orbital theory. In contrast to the Lewis-acid nature of open metal sites in most MOFs, the exposed W ion in W–Cu–BTC is identified as a Lewis-base site, evidenced by the substantial electron donation from W ion to CO₂. Kinetically, the linear CO₂ molecule can be readily bent by forming a CO₂–W complex after overcoming a negligible activation barrier of 0.09 eV. In addition, we present calculated infrared spectra (IR) and X-Ray spectra (XPS) for reference in future experimental studies.