Enhanced light-responsive CO2 adsorption by optimizing azobenzene concentration and introducing an adsorption site

CO 2 adsorption through azobenzene compound light-switching regulation has been extensively investigated. The light responsiveness is significantly influenced by azobenzene (AZO) concentration and adsorption sites, and the complex effects involved in light-responsive adsorption processes. In order to verify the effects of the steric and dipole effects, 4-(Phenylazo) benzoic acid (AZDC) was introduced into the MOF-808 framework, and L -Serine ( L -Ser) modification on the MOF as a new adsorption site. Performance was evaluated based on CO 2 adsorption capacity and changes in adsorption capacity before and after UV irradiation (light-response desorption performance). Experiments confirmed that the adsorbent’s light responsiveness was endowed and that CO 2 adsorption was increased. The light-responsive regulation of CO 2 desorption capacity of optimized AZDC-MOF-808 reaches 3.04 cm 3 ·g −1 , while optimized Ser-AZDC-MOF-808 achieves a light-responsive desorption capacity of 7.05 cm 3 ·g −1 . Light-responsive capacity was inhibited because of excessive AZO concentrations and the L -Ser. The isothermal adsorption heat (Q st ) of optimized Ser-AZDC-MOF-808 decreased from 33.87 kJ·mol⁻¹ to 22.10 kJ·mol −1 , and the electrostatic potential (ESP) decreased after AZO cis-trans isomerism, suggesting a decline in adsorption capacity of CO 2 after exposure to light. We verified the role of AZO concentration and adsorption sites on light response.