Effect of Lithium Doping on the Structures and CO2 Adsorption Properties of Metal-Organic Frameworks HKUST-1

The metal-organic framework HKUST-1 was modified by lithium doping to enhance its CO2 adsorption property. An optimal CO2 adsorption capacity was achieved as a lithium nitrate solution with a moderate concentration was used as the doping agent in the modified HKUST-1. The chemical and crystalline structures of the modified HKUST-1 were characterized in detail. It was found that the crystalline structures and morphologies of HKUST-1 were well preserved after lithium doping. Also, the lithium doping did not deteriorate the thermal stability of HKUST-1. Based on the experimental results of CO2 adsorption by in-situ diffuse reflectance infrared Fourier transform spectroscopy, a possible mechanism of CO2 adsorption in the lithium doped HKUST-1 was proposed. It is believed that the incorporation of lithium has enhanced the interaction between CO2 molecules and the metal-organic frameworks. As a result, the CO2 adsorption capacity greatly increased. These findings and insights are helpful to the development of high-performance materials for CO2 adsorption in the future.