Molecular packing modulated photocatalytic degradation using cocrystal catalysts

Abstract

Persistent organic pollutants such as benzene derivatives threaten aquatic ecosystems due to their toxicity and chemical stability, underscoring the need for efficient and tunable photocatalysts. Herein, we construct three aromatic-perfluoroaromatic (AP) cocrystals via liquid-assisted grinding by co-assembling octafluoronaphthalene (OFN) with planar π-conjugated donors phenanthrene (Phe), pyrene (Py), and coronene (Cor). These cocrystals exhibit distinct molecular packings and electronic characteristics, notably, the triclinic OFN-Py characterized by pronounced structural asymmetry, shows the highest photocatalytic activity. This is attributed to its compact stacking and favorable energy-level alignment, which enhance exciton delocalization, extend carrier lifetimes, and promote efficient hole transport, thereby revealing structure–performance relationships. Mechanistic studies reveal that phenol degradation follows a synergistic reactive oxygen species (ROS) pathway, where oxidation is initiated by holes (h⁺) and hydroxyl radicals (˙OH), synergistically coupled with superoxide radical (˙O₂⁻)-mediated benzoquinone activation, leading to aromatic ring cleavage and mineralization. Significantly, this work provides critical insights into molecular design principles for high-efficiency organic photocatalysts and offers promising strategies for sustainable water remediation.