Cr-N bridged MIL-101@tubular calcined N-doped polymer enhanced adsorption of vaporous toluene under high humidity

High capacity adsorption of volatile organic compounds (VOCs) in high humidity environment is a crux but challenge for atmospheric VOCs governance. In this work, tubular carbonized N-doped polymers (TCNP) were implanted into MIL-101 via N-Cr-O interface self-assembly, enabling high adsorption for vapor toluene in high humidity. Through mechanical ball milling and carbonization, Cr ions were preloaded on TCNP to form highly dispersed 3-5 nm Cr-N crystallite as anchors for growing MIL-101(Cr/Cu). Newly constructed smaller micropores of 6.8 angstrom with aromatic rings/N sites at the interface and doped Cu ions in MOF framework synergistically enhanced pi-pi conjugation and electrostatic interaction for C7H8 molecules. This endowed [TCNP5/MIL(Cr/Cu)](N-Cr) 2.9 times higher toluene uptake (6.34 mmol/g) at low vapor pressure (P/P-0 = 0.02) and 1.9 times diffusivity under high humidity (60% RH) than that of MIL-101(Cr) at 298 K. The adsorption breakthrough curves for vaporous toluene showed that TCNP@MIL-101(Cr/Cu) exhibited outstandingly higher adsorption equilibrium capacity (2.7 mmol/g) under 80% RH, corresponding to approximately 2-10 times than those of reported state-of-the-art adsorbents under similar conditions. This study provided a novel interface construction strategy for hydrophobic MOF composites, which supplied deeper understanding for VOCs adsorption and promoted MOFs practical application in VOCs capture under humid environment.