Facet-dependent nonradical Fenton-like catalysis over Cu₂WS₄: Selective H₂O₂ activation and Cu(III) formation

Deciphering the structure-activity relationship of ternary transition metal chalcogenides is crucial for the development of heterogeneous Fenton-like catalysts. However, the facet-dependent mechanism of ternary metal sulfides such as Cu₂WS₄ in Fenton-like systems has not yet been elucidated. Herein, we report a facet-controlled Cu₂WS₄ catalyst synthesized through a one-pot solvothermal strategy, aiming to reveal the structure-activity relationship during H₂O₂ activation. The results demonstrate that Cu₂WS₄ dominated by the {101} facet (L-Cu₂WS₄) exhibits excellent tetracycline (TC) degradation performance, with degradation rates being 6.15- and 1.24-fold higher than those of its {001}-exposed counterpart (S-Cu₂WS₄) and the classical Fenton system (Fe²⁺/H₂O₂), respectively. Theoretical calculations combined with experimental analysis indicate that the {101} facet possesses stronger adsorption affinity and a lower H₂O₂ activation energy barrier, which promotes the formation of high-valent copper through non-radical pathways, while the {001} facet is prone to adsorb O₂, inhibiting the effective utilization of H₂O₂ and resulting in reduced catalytic activity. The Cu(III)-dominated mechanism enables the L-Cu₂WS₄/H₂O₂ system to operate over a wide pH range (4.08-9.05), exhibit exceptional stability over 5 cycles, and maintain excellent catalytic activity in complex water bodies. Additionally, toxicity tests confirm the detoxification of the treated TC solution, and continuous-flow experiments further demonstrate the application potential of this system in actual water treatment. This study deepens the understanding of the facet-dependent mechanism in Fenton-like reactions and establishes a paradigm for the precise design of copper-based catalysts for water purification.