Photocontrolling cavity dimension enables sustainable lithium capture and rapid release by cyclen-azobenzene network

Regulating the cavity dimension of crown compounds changes its cation uptake ratio and release efficiency, whereas light-responsive triggers may endow the adsorbent with green regeneration functions. Here, we report a cyclen-azobenzene covalent network (C-azobenzene-4,4′-dicarbonyl dichloride [C-ADC]) supported on graphene oxide (GO) as a light-regenerable lithium-selective adsorbent for sustainable lithium extraction. Under room lighting, C-ADC@GO demonstrated a high adsorption loading of up to 15.27 mmol g −1 and an adsorption rate of 36.58 mmol g −1 h −1 . Under UV light irradiation, cyclen’s cavity is expanded by the pulling of cis -azobenzene, releasing the adsorbed ions within 6 min. The relevant Li + /Mg 2+ and Li + /Na + selectivities reach 11.44 and 31.26. It could extract and purify lithium in synthetic Atacama salt-lake brine from 2.5% to 91.2%. A low energy consumption of 8.84 kWh per ton of Li 2 CO 3 is estimated. This work pioneers a new approach for designing next-generation adsorption materials for energy-efficient and sustainable ion extraction and purification.