Creating Cu(I)-decorated defective UiO-66(Zr) framework with high CO adsorption capacity and selectivity

Developing a highly effective material for CO storage and separation is a challenge. In this study, we first used microwave-assisted continuous-flow synthesis to create defective UiO-66(Zr) frameworks with improved surface area and pore structures, which is highly efficient for large-scale production. The defect concentration of UiO-66(Zr) was rapidly and effectively controlled within a short reaction time of 10 min. Different amounts of Cu2+ were loaded onto defective UiO-66 samples, followed by reducing Cu2+ to Cu+ to obtain Cu(I)@UiO-66 adsorbents (Cu(I)@UiO). X-ray diffraction (XRD), N2-adsorption, FT-IR, SEM, TEM, thermogravimetric analysis (TGA), and XPS analyses were used to characterize the physicochemical properties of the prepared adsorbent materials. Gas adsorption experiments revealed that Cu(I)-decorated defective UiO-66 exhibited high CO adsorption capacity due to the π complexation between Cu+ and CO. The CO adsorbing amount and CO selectivity onto the Cu(I)@UiO-66 samples were improved by adjusting the defect concentration and Cu(I) load on the UiO-66 host. The breakthrough experiment confirms that this defective Cu(I)@UiO adsorbent can efficiently separate CO/N2 mixture under dynamic mixture flow conditions. Furthermore, after several cyclic adsorption–desorption experiments, the defective Cu(I)@UiO-66 is highly regenerable and has a good oxygen-resistant ability. The study describes a simple and scalable method for producing π-complexation adsorbent for CO adsorption.