Engineering a Zn-NC electron bridge boosting charge transfer in ZnO/CN Z-scheme heterojunction for efficient photocatalytic disinfection.

Although photocatalytic disinfection can avoid secondary pollution and other shortcomings compared to traditional disinfection methods, its development is seriously hindered by poor charge separation and transfer efficiency. Herein, we design a Zn-NC (single Zn atoms embedded in nitrogen-doped carbon) bridged ZnO/CN Z-scheme heterojunction (ZnO/Zn-NC/CN) with robust interface contact by a multi-interfacial engineering strategy to achieve highly efficient separation and transfer of charge. Experimental and theoretical analyses demonstrate that the tightly integrated interface and excellent electrical conductivity of Zn-NC electron bridges ensure effective transfer of photogenerated charge carriers. Compared to ZnO/CN, the introduction of Zn-NC electron bridges induces charge rearrangement at the interface, generating a strong built-in electric field in the ZnO/Zn-NC/CN Z-scheme heterojunction to facilitate the separation and transfer of photogenerated charge carriers. Furthermore, Zn-NC electron bridges effectively promote the adsorption and activation of oxygen on the surface of ZnO/Zn-NC/CN, enhancing the generation of reactive oxygen species for rapid bacteria elimination in water. Consequently, the ZnO/Zn-NC/CN Z-scheme heterojunction, at a concentration of 100 ppm, achieves 99.9 % antibacterial efficiency against methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, and Escherichia coli at a bacterial concentration of ∼ 10 CFU/mL under AM 1.5G simulated sunlight irradiation for 60 min, which is approximately 1.05 times higher than that of ZnO/CN. Moreover, ZnO/Zn-NC/CN maintains a 99.9 % bactericidal efficiency for natural water treatment using a homemade microreactor, demonstrating its potential for water disinfection.