Synergy of Ti-O-based heterojunction and hierarchical 1D nanobelt/3D microflower heteroarchitectures for enhanced photocatalytic tetracycline degradation and photoelectrochemical water splitting

Solar-driven photocatalytic pollutant degradation and photoelectrochemical (PEC) water splitting are promising approaches for green environmental remediation and solar energy conversion. In this work, novel hierarchical 1D K₂Ti₆O₁₃ nanobelt/3D TiO₂ microflower heteroarchitectures were controllably synthesized via a facile hydrothermal route. The optimal K₂Ti₆O₁₃/TiO₂ hybrids exhibited much higher photocatalytic activity than single catalysts and good stability for tetracycline (TC) degradation. The removal of TC was also evaluated at different catalyst dosage, temperature, pH and concentration of TC solutions. The contributions of radical species for TC degradation followed a sequence of [rad]OH > h⁺ > [rad]O²⁻. The intermediates and degradation pathway of TC were determined by LC-MS analysis. Furthermore, significantly enhanced PEC responses of K₂Ti₆O₁₃/TiO₂ composites were also observed compared with the single components, fully proved by open-circuit potential, LSV, transient photocurrent and EIS analysis. Such superior photoactivities were mainly attributed to the synergistic effects between the strongly coupled K₂Ti₆O₁₃/TiO₂ heterojunctions and hierarchical 1D/3D micro-nano architectures, including larger surface area, increased light adsorption and charge separation efficiency. Overall, this work offers a controllable strategy to design novel Ti-O-based heterostructures with hierarchical micro-nano architectures and outstanding performance for photocatalytic and PEC applications.