Engineering Co–O–Zn bonds in CoWO4/ZnO heterojunctions toward boosted charge separation and photothermal antibacterial activity

Abstract

Engineering electron-bridge bonds at heterojunction interfaces offers an effective strategy to enhance photocatalytic performance. This paper reports the selective construction of Co–O–Zn electron-bridge bonds in CoWO₄/ZnO heterostructured nanotubes via an electrospinning–calcination process. The preferential formation of Co–O–Zn bonds over W–O–Zn bonds at CoWO₄ (100)/ZnO (101) interfaces, accompanied by electron transfer from Zn to Co, indicates that h⁺-rich Zn and e⁻-rich Co sites serve as oxidation and reduction centers, respectively. The optimized CoWO₄/ZnO-0.5 composite exhibits dual photocatalytic functionality, achieving 95% UV-Vis tetracycline degradation within 140 min and 91% NIR degradation within 240 min, with strong cycling stability (efficiency loss of only 5.21% and 4.71% after five cycles, respectively). A fluorescence lifetime of 1.37 ns provides direct evidence of accelerated charge-transfer kinetics through Co–O–Zn electron bridges, enabling rapid separation of photogenerated electron–hole pairs. ECOSAR simulations confirm that degradation products are up to 26.2-fold less toxic than the original compound. Under 0.5 W cm⁻² laser irradiation, the material demonstrates pronounced photothermal properties, with rapid heating to 172.6 °C (solid, 100 s) and 52.9 °C (liquid, 150 s). The integration of photocatalysis and photothermal sterilization through directional bond engineering provides mechanistic insights into dual-function enhancement and establishes an atomic-level framework for designing heterojunctions for energy and sustainability applications.