Self-sacrificial synthesis of Cu3(HHTP)2 on Cu substrate for recyclable NH3 gas adsorption with energy-efficient photothermal regeneration

Abstract

The efficient adsorption and removal of toxic gases, particularly ammonia (NH₃), remains a critical challenge in environmental management and industrial safety. Metal–organic frameworks (MOFs) have emerged as promising gas adsorbents due to their tunable structures and high surface area. However, the strong interaction between NH₃ and MOFs poses challenges for the regeneration and reusability of MOF adsorbents, often requiring energy-intensive desorption methods. This study proposes a sustainable approach for regenerating adsorption sites for recyclable gas adsorbents. We present a facile method for the direct synthesis of Cu₃(HHTP)₂ on a Cu mesh substrate (Cu₃(HHTP)₂@Cu), utilizing the Cu metal itself as a precursor to eliminate the need for external metal sources. The resulting Cu₃(HHTP)₂@Cu serves as a recyclable NH₃ adsorbent, leveraging the π-conjugated hexahydroxytriphenylene (HHTP) ligand for photothermal conversion under sunlight irradiation, where photo-generated heat facilitates NH₃ desorption. The study further explores the effect of an external voltage on the NH₃ adsorption performance and crystalline structure of Cu₃(HHTP)₂@Cu. Our findings demonstrate that Cu₃(HHTP)₂@Cu achieves efficient NH₃ desorption through a minimally invasive and energy-efficient mechanism, addressing the limitations of conventional adsorbents.