Electrospinning synthesis of porous Bi₁₂TiO₂₀/Bi₄Ti₃O₁₂ composite nanofibers and their photocatalytic property under simulated sunlight

Porous composite nanofibers consisted of cubic Bi₁₂TiO_20, and orthorhombic Bi₄Ti₃O₁₂ with pore size of 5–10 nm have been successfully synthesized by combining electrospinning with calcination for photodegrading methyl orange (MO). Calcination temperature has a great effect on the ratio of Bi₁₂TiO₂₀ and Bi₄Ti₃O₁₂ and their morphology, which in turn affects the photocatalytic property of the products. MO was almost completely degraded over the as-prepared samples obtained under the optimizing calcination temperature of 500 °C after irradiating for 40 min under simulated sunlight. Besides, cycle and regeneration experiments show that the porous Bi₁₂TiO₂₀/Bi₄Ti₃O₁₂ composite nanofibers possess fine cycle stability and regeneration ability, after the regenerative photocatalyst was recycled twice, 91% of the MO was degraded. Based on the characterization results, the mechanism of the improvement in photocatalytic property of Bi₁₂TiO₂₀/Bi₄Ti₃O₁₂ composite nanofibers was also investigated, and h⁺ played a major role in the photodegradation of MO. In addition, the as-prepared Bi₁₂TiO₂₀/Bi₄Ti₃O₁₂ composite nanofibers show a certain capacity of photocatalytic hydrogen production under the simulated sunlight. This work not only provides a porous fiber with good photocatalytic activity, but also provides a reference for the preparation and performance study of other fibers.