Ultrafast room temperature synthesis of GrO@HKUST-1 composites with high CO2 adsorption capacity and CO2/N2 adsorption selectivity

An ultrafast synthesis method is developed for the preparation of composites of graphite oxide and HKUST-1, GrO@HKUST-1. Fast synthesis of GrO@HKUST-1 composites can be quickly achieved at room temperature within 1 min. The synthesized composites were characterized by XRD, SEM, N2 adsorption, FTIR and TGA. The isotherms of CO2 and N2 on the as-synthesized materials were measured and the isosteric heats of CO2 adsorption were estimated. The CO2/N2 adsorption selectivities were predicted by means of ideal adsorbed solution theory (IAST). Results show that the GrO@HKUST-1 composites have higher BET surface area and pore volume than the parent HKUST-1. The CO2 adsorption capacity of 2GrO@HKUST-1 (2% of GrO) is up to 9.02 mmol/g at 1 bar and 273 K, giving an increase of 32% in comparison of the parent HKUST-1. The isosteric heat of CO2 adsorption on 2GrO@HKUST-1 is slightly higher than that of HKUST-1, suggesting the stronger interaction between CO2 molecules and 2GrO@HKUST-1. The CO2/N2 adsorption selectivity of 2GrO@HKUST-1 is significantly enhanced over pristine HKUST-1. At 1 bar, the CO2/N2 adsorption selectivity of 2GrO@HKUST-1 is up to 186, while that of parent HKUST-1 is only 103. This rapid room temperature synthesis route is promising for new MOF-based composites.