Solvent-exchange process in MOF ultrathin films and its effect on CO2 and methanol adsorption

Metal-organic framework (MOF) activation is crucial for the use of MOFs in several applications and solvent-exchange process is a necessary step in many activation methods. In this contribution, we have explored in situ MOF monolayer film formation at the air-water interface. Nanoparticles (NPs) of the Al trimesate MIL-96(Al) retain chloroform into their micropores, which considerably diminishes the CO2 adsorption capacity of MOF films. However, a solvent-exchange process between chloroform and water increases CO2 film adsorption capacity by 30%. Total Reflection X-Ray Fluorescence (TRXF) allows studying the kinetics of this process at the air-water interface, that strongly depends on the NP size. The conclusions derived from in situ studies allow optimizing the ex situ activation procedure of MIL-96(Al) films deposited onto quartz crystal microbalance (QCM) substrates in order to maximize CO2 and methanol adsorption.We acknowledge the financial support from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement number 608490, project M4CO2; and also financial support from Spanish MINECO and FEDER (projects MAT2016-78257-R and MAT2017-86826-R), from the Aragon Government (DGA) and FEDER (research group E31_17R) and from the University of Zaragoza (JIUZ-2015-CIE-02). M.A. Andrés acknowledges the support of Ministerio de Educación from the Spanish Government under a FPU grant (Formación de Profesorado Universitario, FPU14/05367).Peer reviewe