The S-Cu-O bonds boosted efficient photocatalytic degradation of semi-coherent interface Cu2O/Cu7S4 heterojunction

The steric effect caused by the lattice mismatch between the two phases hinders the separation and transfer of photogenerated carriers, which is one of the important factors limiting the activity of heterojunction photocatalysts. In this paper, semi-coherent interface Cu2O/Cu7S4 heterojunction was successfully constructed based on the epitaxy growth method of anion exchange. The degradation of tetracycline by semi-coherent interface Cu2O/Cu7S4-30 heterojunction under simulated visible light reached 95.3 % at 60 min, which is a significant improvement compared with single-phase catalysts and ordinary heterojunction catalysts (Cu2O/Cu7S4-mix). The experimental characterization and theoretical calculations confirmed the existence of unique S-Cu-O chemical bonds in the semi-coherent interface Cu2O/Cu7S4 heterojunction. On the basis of heterojunction energy band bending and the formation of built-in electric fields, the S-Cu-O bonds can act as a specific bridge to further facilitate the separation, transfer and delivery of photoelectrons and holes, which contributes to the generation of more oxidatively active species (mainly superoxide radicals and holes). In addition, based on experimental characterization and theoretical calculations, the intermediates, degradation pathways and photodegradation mechanisms of the degradation process have also been discussed in detail.