Synthesis and hydrogen storage studies of metal−organic framework UiO-66

Metal−organic framework UiO-66 has high chemical and thermal stability. However, it is difficult to produce such Zr-based MOFs with good crystalline morphology. Here, highly pure metal−organic framework UiO-66 has been synthesized at low temperature (50 °C). The as-synthesized sample has been characterized by X-ray diffraction, thermogravimetric analysis, nitrogen adsorption, and scanning electron microscopy. Its hydrogen-storage capacity has been measured by means of an Intelligent Gravimetric Analyser. The results showed that UiO-66 was synthesized in octahedral crystals of well-defined sizes (150−200 nm) and had a high specific surface area (1358 m2/g). The as-synthesized UiO-66 showed a significant hydrogen uptake even at a moderate pressure, which increased to 3.35 wt% at 77 K and 1.8 MPa. A grand canonical Monte Carlo simulation (GCMC) has been employed to calculate the adsorption of hydrogen in UiO-66. The result of this simulation provided a theoretical foundation for the experimental results. [Display omitted] ► UiO-66 was synthesized in octahedral crystals of well-defined sizes at low temperature. ► The sample had a high specific surface area (1358 m2/g). ► UiO-66 showed a significant hydrogen uptake increased to 3.35 wt% at 77 K and 1.8 MPa. ► According to GCMC simulation, the phenyl rings of the BDC linkers were the first adsorption sites.