Metal–(organic cocrystal) framework with a photothermal effect boosting the photocatalytic degradation of pollutants

Abstract

Owing to a molecularly-regulated energy level and charge mobility, organic cocrystals (OCs) exhibit huge potential in photonic and electrical fields. However, the lack of pore structures, few catalytic sites, and narrow bandgaps of OCs greatly suppress their development in photocatalytic fields. We designed and synthesized a novel type of metal–(organic cocrystal) framework (MOCF) in which the acridine (Ac) molecule was confined in the framework of Ca-NDI MOF. That is, the Ac@[Ca-NDI] single crystal. This MOCF maintained the redox ability, pore structure, and catalytic sites of Ca-NDI MOF. Besides, the close stacking model between Ac and H₄BINDI induced strong charge transfer interactions. Hence, the absorption range of Ac@[Ca-NDI] was extended into the near-infrared region, with excellent photothermal conversion efficiency (70.65%) under 808 nm irradiation. In the photodegradation of phenol, the photocatalytic rate of MOCF was six-times higher than that of Ca-NDI MOF, attributed to a synergistic photothermal and photocatalytic effect. In the preparation of OCs, MOCF overcame the molecular solubility and size limitations of traditional solvent methods. As a proof-of-concept, this work provides a novel approach for OCs preparation, but also integrates photothermal and photocatalytic dual-functions in a single crystal, thereby boosting the development of functional organic materials.