Polyethyleneimine modified nitrogen-doped titanate nanotubes for boosting carbamazepine degradation and mineralization by synergistic effect of photocatalysis and nanozyme

As an emerging class of enzyme-mimicking nanomaterials, nanozymes provide a novel strategy for eliminating water pollutants. Their catalytic efficiency can be significantly boosted by light irradiation, owing to its controllability and activation potential. However, the synergy between nanozyme and photocatalysis remains underexplored, especially for degrading pharmaceuticals and personal care products (PPCPs), and requires deeper mechanistic understanding. This study achieves a breakthrough in carbamazepine (CBZ) degradation by pioneering a hydrogen bond-bridged polyethyleneimine (PEI) modified nitrogen-doped titanate nanotubes (NTNTs) catalyst that uniquely combines photocatalytic and enzyme-mimicking functions in a single system. Nitrogen dopant incorporation into titanate nanotubes (TNTs) extends light absorption range, facilitates charge carrier separation, and elevates photocatalytic performance. Simultaneously, Ti-N interactions modify electronic configurations, conferring peroxidase-like characteristic to NTNTs. Branched PEI hydrogen-bonded to NTNTs further expands the specific surface area, multiplies active sites, extends visible-light response, and serves as an electron conduit for enhanced interfacial charge transfer. Moreover, the activated hydrogen peroxide (H 2 O 2 ) facilitates Ti(III)/Ti(VI) redox cycling, which not only amplifies hydroxyl radical production but also establishes a self-sustaining catalytic loop, thereby enhancing the photo-enzyme synergistic effect through continuous generation of reactive oxygen species. The catalyst removes 98 % CBZ in 30 min with 66.5 % TOC reduction and maintains good reusability and stability. This work advances the design of multifunctional catalytic systems by integrating photocatalysis and nanozyme for sustainable water treatment.