Precise heating of adsorption sites induced by visible light irradiation

Adsorption is an effective technique for CO₂ capture but releasing CO₂ from adsorbents is energy-intensive because of low thermal conduction in fixed adsorption beds and massive energy loss. Here, Ag nanoparticles were targeted at active sites and used as nanoheaters by surface plasmon resonance effect to precisely heat adsorption sites. UiO-66-NH₂ was selected as the typical CO₂ adsorbent, and Ag⁺ ions were used to coordinate with the –NH₂ groups and then in-situ reduced to Ag nanoparticles. Under visible-light irradiation, Ag nanoparticles convert light energy to heat and transfer heat to the nearby active sites rapidly, resulting in the efficient temperature elevating of active sites. CO₂ can receive the energy for desorption without long-distance heat transfer. The adsorbent can be readily heated by 25 ℃ within 10 min and achieve almost 100% desorption of CO₂ upon light irradiation during the test of the isotherm at room temperature. In contrast, pristine UiO-66-NH₂ desorbed only 22.5% of CO₂. This strategy also works in the fixed bed, and may provide a new avenue for the development of advanced desorption systems.