Engineering hierarchical porous oxygen-deficient TiO2 fibers decorated with BiOCl nanosheets for efficient photocatalysis

The hierarchical porous oxygen-deficient TiO2 (TiO2-delta) fibers decorated with BiOCl nanosheets, for the first time, were synthesized through a sol-gel method combined with centrifugal spinning, and subsequent heat treatment under steam. Therein, the byproduct water-soluble NaCl crystal was recycled and used as the self-manufactured and self-sacrificial template. The dissolving out of NaCl for the in situ preparation of BiOCl on the surface of TiO2-delta generates rich mesoporous fiber structure. The flower-like BiOCl nanosheets provide large surface area for the adsorption of reactants, and more light scattering/reflection channels for enhancing light absorption. A series of characterizations confirmed that the introduction of oxygen vacancies in TiO2 broadens the light response to visible range, and the promotion of charge separation due to the formation of p-n junction between BiOCl and TiO2-delta. As a result, the BiOCl/TiO2-delta fiber exhibits enhanced broadband photocatalytic performance in the degradation of reactive brilliant red and colorless phenol. The apparent reaction rate constant achieved by the optimized BiOCl/ TiO2-delta composite (0.0636 min(-1)) far surpasses that of TiO2-delta fibers (0.0026 min(-1)) by a factor of 24 under visible light irradiation. The reactive species involved in photocatalysis were detected by scavenger experiments and electron spin resonance spectra. The possible charge transfer processes and mechanism were explored and discussed in detail. This work provides novel insight into the design and synthesis of broadband and effective heterostructure photocatalysts for practical wastewater treatment.