In-Situ Construction of 2D/2D CuCo2S4/Bi2WO6 contact heterojunction as a visible-light-driven fenton-like catalyst with highly efficient charge transfer for highly efficient degradation of tetracycline hydrochloride.

The heterogeneous photo-Fenton technology by integrating the merits of photocatalysis and Fenton oxidation is verified to be a promising environmental purification technology due to its relatively mild reaction conditions, low cost and high treatment efficiency. Herein, we demonstrate the fabrication of Type-II CuCo 2 S 4 /Bi 2 WO 6 heterojunction as an effective catalyst for the removal of tetracycline hydrochloride (TC-HCl). Two photoactive components are combined to form a two-dimensional/two-dimensional (2D/2D) heterojunction by coupling 2D CuCo 2 S 4 with 2D Bi 2 WO 6 nanosheets, in which CuCo 2 S 4 cocatalyst broadens the light responsive range, facilitates the separation and transfer of photogenerated carriers. Most importantly, CuCo 2 S 4 initiates the photo-Fenton catalysis by utilization photogenerated electrons to react with Cu (II) and Co (III) in presence of hydrogen peroxide (H 2 O 2) to accelerate the circulation of the photo-Fenton reaction. Thus, the generated OH and·O 2 - are applied as potent free radical species for the catalytic degradation of pollutants. The synthesized CuCo 2 S 4 /Bi 2 WO 6 heterostructures exhibited excellent photo-Fenton catalytic activity for TC-HCl removal. The rate constant (k app /min−1) of 0.5% CuCo 2 S 4 /Bi 2 WO 6 heterojunction is about 1.8 times higher than pure Bi 2 WO 6. Recycling experiments show that the catalyst maintained its high activity after being reused for 4 cycles, reflecting its good stability. Meanwhile, hydroxyl radical (·OH) and superoxide radical (·O 2 -) were identified as oxygen active species, taking a key role in the degradation of TC-HCl. Based on the trapping experiment and energy band analysis, a reasonable photo-Fenton oxidation mechanism for Type-II CuCo 2 S 4 /Bi 2 WO 6 heterojunctions is put forward. This work will arouse researchers' enthusiasm for introducing transition metal sulfides as cocatalyst to design heterogeneous photo- Fenton catalyst. In-situ coupling two-dimensional (2D) CuCo 2 S 4 nanosheets on 2D Bi 2 WO 6 nanosheets to efficiently facilitate the separation and transfer of photogenerated charges for photo-Fenton degradation of TC-HCl. [Display omitted] • CuCo 2 S 4 /Bi 2 WO 6 heterojunctions were synthesized by in-situ hydrothermal reaction. • The unique 2D/2D heterojunction can efficiently facilitate the separation and transfer of photogenerated charges. • The synthesized CuCo 2 S 4 /Bi 2 WO 6 heterojunctions exhibited excellent photo-Fenton catalytic activity for the degradation of TC-HCl. • A reasonable photo-Fenton oxidation mechanism for Type-II CuCo 2 S 4 /Bi 2 WO 6 heterojunctions is proposed. [ABSTRACT FROM AUTHOR]