Photothermal-assisted NH3 release in a bipyridinium-functionalized metal-organic framework adsorbent

Widespread deployment of NH3-adsorbing MOF materials remains challenging due to the significant energy-penalty of regeneration. In this work, we address this limitation by integrating photothermal technologies into a bipyridinium-functionalized MOF matrix, enabling effective NH3 desorption in a more eco-friendly and sustainable manner. This MOF adsorbent exhibits selective NH3 capture via specific hydrogen bonding interactions, rendering it suitable for purifying effluent gases in industrial NH3 synthesis. The NH3 adsorption process is accompanied by an obvious color change due to the formation of bipyridinium radicals through an electron transfer reaction between NH3 molecules and bipyridinium ligands. This distinctive property endows the MOF with favorable NH3 detection capabilities. Furthermore, the colored MOF matrix functions as an exceptional photothermal medium under 808 nm laser irradiation, effectively facilitating the release of captured NH3 molecules through light-triggered localized heating. Importantly, the synthesis of this MOF material can be scaled up to gram-level with minimal complexity using a straightforward one-pot reflux method, significantly enhancing its practical applicability. An eco-friendly and sustainable NH3 desorption process has been successfully realized in a bipyridinium-bearing MOF adsorbent via free radical-dominated photothermal conversion for localized heating.