Design of a highly efficient Cu-based catalyst with two functional areas: The role of Cu0 and oxygen vacancies in Fenton-like system

In Fenton process, excess hydrogen peroxide (H2O2) was usually input into reaction systems to achieve high reaction efficiency, which has become one of the development bottlenecks for applications. Herein, a novel strategy for designing Cu catalyst (G-Cu) with two functional regions (zero-valent copper (Cu0) and oxygen vacancies (OVs)) was proposed to mitigate this problem. Experimental results and DFT calculation results collaboratively verified that Cu0 sites were able to produce H2O2 in situ through activating dissolved oxygen (DO), thereby reducing the input of H2O2. Meanwhile, the presence of OVs could improve the electron transfer capability of material and lengthen the O-O bond of H2O2, thus promoting the activation of H2O2 over catalyst surface. As a result, G-Cu achieved higher oxytetracycline (OTC) degradation efficiency (89.2%) than unmodified Cu catalyst (28.29%) at a small dosage of H2O2 (5 mM), in which OH, O2−, and 1O2 were involved in the degradation process. Meanwhile, this system could operate well in a broad pH range (3–11), which had a certain possibility in practical application. In a word, this work offers a valuable strategy for reducing the input of H2O2 in Fenton process.