A Multivalent Copper Polypyridyl Coordination Polymer for Heterogeneous Dark-Fenton Degradation of Organic Dyes

The development of materials for organic dye degradation is a promising alternative for environmental protection and wastewater treatment. Herein, a mixed-valence copper polypyridyl coordination polymer [CuIICuI2(DNP*)Cl3(SCN)]n·2nCH3CN (1) (DNP* = 2,6-di(1,6-naphthyridin-2-yl)pyridine) has been solvothermally synthesized and demonstrates a two-dimensional (2D) structure with CuI/II centers connected by DNP* and SCN– anions. Owing to unsaturated coordination sites and valence state cycling of CuI/II centers, complex 1 exhibits excellent Fenton degradation activity with rates of 93.5% (for Methylene blue, MB), 80.0% (for Rhodamine B, RhB) and 80.1% (for Methyl Orange, MO) under dark conditions within 120 min. The Fenton catalytic degradation pathways and mechanisms were investigated by selecting MB as an example. Furthermore, the MB degradation follows the first-order reaction kinetic model, exhibiting a total organic carbon (TOC) removal rate of 24.6% and a reaction activation energy of 81.52 kJ·mol–1. This work presents an effective strategy for wastewater treatment by developing multivalent coordination polymers.