Oxygen Vacancy-Rich CuO _<i>x</i> /BiVO ₄ Heterojunction Engineering with Optimized Charge Separation for High-Efficiency Solar-Driven Photocatalysis

Oxygen vacancies, as critical lattice defects, demonstrate remarkable advantages in photocatalysis by optimizing electron transport and electrochemical properties, promoting charge separation, and enhancing surface reactivity to improve the photocatalytic performance. Furthermore, the construction of band-aligned heterostructures serves as a vital strategy for optimizing carrier dynamics and boosting light absorption. Herein, a facile H2O2-mediated synthesis strategy was employed to fabricate oxygen vacancy-rich CuOx/BiVO4 (CuOx/BVO) heterojunction photocatalysts. CuOx nanoparticles with abundant oxygen vacancies were successfully loaded onto BVO to form a defective type-II heterojunction. Characterization results revealed that the CuOx/BVO composite exhibited enhanced visible-light absorption, improved charge separation efficiency, and accelerated surface reaction kinetics. Under simulated sunlight, photogenerated holes and electrons migrated to the CuOx and BVO interfaces, participating in oxidation and reduction reactions. The optimized CuOx-3/BVO composite achieved a 4.7-fold higher photocatalytic degradation efficiency for Rhodamine B compared to that of pristine BVO, while maintaining excellent stability over six cycles. This work provides valuable insights for designing defect-engineered heterojunctions in advanced photocatalytic applications.