Imparting surface hydrophobicity to metal–organic frameworks using a facile solution-immersion process to enhance water stability for CO₂capture

Abstract

The water sensitivity of metal-organic frameworks (MOFs) poses a critical issue for their large-scale applications. One effective method to solve this is to provide MOFs with a hydrophobic surface. Herein, we develop a facile solution-immersion process to deposit a hydrophobic coating on the MOFs' external surface without blocking their intrinsic pores. The water contact angle of the surface hydrophobic (SH) MOFs is ∼146°. The hydrophobic coating not only greatly enhances MOFs' water stability but also provides durable protection against the attack of water molecules. When exposed to liquid water, the SH samples well retain their crystal structure, morphology, surface area and CO₂ uptake capacity. However, the as-synthesized (AS) samples nearly collapse and lose their porosity as well as CO₂ uptake capacity after the same exposure. This study opens up a new avenue for the MOFs' application of gas sorption in the presence of water.