A novel design of Cu(I) active site on the metal-organic framework for exploring the structural transformation of Fenton-like catalysts through in situ "capturing" OH.

The mutual transformation of reactive oxygen species may affect the structural transformation of catalysts during the Fenton-like processes. Its in-depth understanding is essential to achieve high catalytic activity and stability. In this study, a novel design of Cu(I) active sites based on the metal-organic framework (MOF) is proposed to "capture" OH produced via Fenton-like processes and re-coordinate the oxidized Cu sites. The Cu(I)-MOF presents an excellent removal efficiency for sulfamethoxazole (SMX), with a high removal kinetic constant of 7.146 min. Combing DFT calculations with experimental observations, we have revealed that the Cu of Cu(I)-MOF exhibits a lower d-band center, enabling efficient activation of HO and spontaneous "capturing" of OH to form Cu-MOF, which can be reorganized into the Cu(I)-MOF through molecular regulation for recycle. This research demonstrates a promising Fenton-like approach for solving the trade-off between catalytic activity and stability and provides new insights into the design and synthesis of efficient MOF-based catalysts for water treatment.