The Role of Water in Carbon Dioxide Adsorption in Porphyrinic Metal‐Organic Frameworks
Bettina Baumgartner, P. Tim Prins, Jaap N. Louwen, Matteo Monai, Bert M. Weckhuysen
Abstract
Abstract Capturing and converting CO 2 through artificial photosynthesis using photoactive, porous materials is a promising approach for addressing increasing CO 2 concentrations. Porphyrinic Zr‐based metal‐organic frameworks (MOFs) are of particular interest as they incorporate a photosensitizer in the porous structure. Herein, the initial step of the artificial photosynthesis is studied: CO 2 sorption and activation in the presence of water. A combined vibrational and visible spectroscopic approach was used to monitor the adsorption of CO 2 into PCN‐222 and PCN‐223 MOFs, and the photophysical changes of the porphyrinic linker as a function of water concentration. A shift in CO 2 sorption site and bending of the porphyrin macrocycle in response to humidity was observed, and CO 2 /H 2 O competition experiments revealed that the exchange of CO 2 with H 2 O is pore‐size dependent. Therefore, humidity and pore‐size can be used to tune CO 2 sorption, CO 2 capacity, and light harvesting in porphyrinic MOFs, which are key factors for CO 2 photoreduction.