Solar-light-triggered regenerative adsorption removal of styrene by silver nanoparticles incorporated in metal–organic frameworks

Adsorption is an attractive technique for the removal of volatile organic compounds (VOCs) from polluted air; however, it is still challenging to efficiently release adsorbed VOCs. Herein, in consideration of the unprecedented VOC adsorption capability of MOFs and excellent photothermal effects of Ag nanoparticles, a novel photodynamic Ag/UiO-66 adsorbent was constructed by integrating Ag nanoparticles with UiO-66 using a colloidal deposition method. The obtained Ag/UiO-66 samples were found to possess the excellent porosity and high styrene adsorption capability of parent UiO-66. Upon exposure to simulated solar light, Ag nanoparticles could convert light energy into thermal energy, which gave rise to light-induced localized heat near Ag nanoparticles. Subsequently, this localized heat triggered the thermal desorption of the adsorbed styrene from Ag/UiO-66, thus successfully realizing efficient in situ regeneration of Ag/UiO-66 under solar light irradiation. Moreover, the desorption capacity can be effectively regulated by the Ag content. More importantly, the regenerability of Ag/UiO-66 remained intact even after five adsorption–desorption cycles; however, pure UiO-66 recovered only 51.6% of its adsorption capacity and maintained 77.0% of its desorption capacity after five cycles. Furthermore, adsorption kinetic parameters and a possible regeneration mechanism are described in detail.