Z-Scheme CeO2@PDA/BiOBr heterojunction with PDA electronic transfer medium for photocatalytic elimination of methylene blue and tetracycline

Abstract

Herein, a Z-Scheme CeO₂@PDA/BiOBr heterojunction was prepared through in situ self-polymerization and hydrothermal method, where PDA layer not only facilitated the attachment between CeO₂ and BiOBr, but also acted as an electron transfer bridge in the composite. A close interfacial contact between CeO₂@PDA nano-particles and flower-like BiOBr was observed via scanning electron microscope images. Compared with CeO₂, CeO₂@PDA and BiOBr, the CeO₂@PDA/BiOBr exhibits smaller band gap energy, higher transient photocurrent and lower transfer resistance. The CeO₂@PDA/BiOBr was effective in decomposition of tetracycline (TC) and methylene blue (MB) with visible light illumination, demonstrating 100 % elimination efficiency of TC and MB. Furthermore, after five recycles, 84.66 % and 89.41 % of the original photocatalytic capability for TC and MB degradation, respectively, were preserved, revealing the cycling stability and reusability of CeO₂@PDA/BiOBr. Moreover, the CeO₂@PDA/BiOBr also maintains relatively stable removal efficiency of contaminants over the pH range of 2–9. The enhanced properties of CeO₂@PDA/BiOBr is mainly owning to the Z-scheme heterojunction between CeO₂ nanoparticles and flower-like BiOBr and PDA interfacial interaction layer, which boosted the separation and motability of photo-excited e/h⁺ pairs. The present work offers a reference for the design and construction of composite photocatalysts with efficient interfacial electron transfer medium.