Engineering electron distribution of Cu2O/FeOx@CNFs p–n heterojunction nanozyme: boosting the Fenton reaction efficiency†

Nanozymes with high efficiency, stability, and cost-effectiveness hold great potential for various applications. However, their use in Fenton reactions is limited by the rate-limiting step of Fe³⁺ reduction. Herein, oxygen vacancy-rich Cu₂O/FeO_xp–n heterojunction on carbon nanofibers (Cu₂O/FeO_x@CNFs) is developed to boost Fenton reaction efficiency. The heterojunction structure harnesses a built-in electric field to facilitate charge carrier separation, with Cu⁺ serving as the electron donor for accelerating the reduction of surface-generated Fe³⁺. Meanwhile, Cu₂O/FeO_x@CNFs encourages abundant lattice defects, creating ample catalytic sites and oxygen vacancies. Theoretical insights revealed that the defect-rich property well regulated the electron distribution at the atomic level, driving the adsorption–desorption process and accelerating Fenton reaction kinetics. As such, Cu₂O/FeO_x@CNFs demonstrates an affinity for H₂O₂ up to 200 times that of natural horseradish peroxidase (HRP) and a V_max 3.40 times higher. The CNFs used as the support well confine Cu₂O/FeO_x, endowing Cu₂O/FeO_x@CNFs with high stability and biocompatibility, and fast mass transport. The strong intrinsic magnetic properties of Cu₂O/FeO_x@CNFs contribute to recyclability. Finally, Cu₂O/FeO_x@CNFs is successfully employed in efficient pollutant degradation and antibacterial applications, offering new insights into the rational design of nanozymes with desired properties.