Construction of g-C3N4/Bi4Ti3O12 hollow nanofibers with highly efficient visible-light-driven photocatalytic performance

Abstract

The exploration and development of effective and persistent visible-light-responsive photocatalysts for environmental remediation is regarded as one of the most challenging current research areas. Herein, a novel g-C3N4/Bi4Ti3O12 (CN/BTO-X; X = 6, 9 and 10.8) hollow nanofiber composite was fabricated through a convenient electrospinning/calcination technique, followed by thermal polymerisation. The SEM and TEM images showed that CN/BTO composite mainly comprised a hollow nanofiber morphology with a diameter of 110 ± 20 nm. The XPS result confirmed the interfacial interaction between BTO and CN, implying the formation of a heterojunction between these components. Photocatalytic measurements revealed that the as-synthesized CN/BTO composite exhibited excellent and stable photocatalytic behaviour of dislodging multiple pollutants (including RhB, MO, TC and Cr (VI) etc.) with visible light (λ > 420 nm). Among these prepared composites, the CN/BTO-9 sample exhibited the highest photocatalytic performance with the rate constants of 0.03064 min−1 (TC), 0.11274 min–1 (RhB), 0.04474 min–1 (MO) and 0.01938 min–1 (Cr(VI)), respectively. The outstanding catalytic performance was ascribed to the high specific surface area, improved visible-light adsorption, heterostructure of CN/BTO with strong oxidative ability and efficient separation of photoinduced charge carriers, and its unique hollow nanofiber structure. The active species-capturing experiments and ESR tests verified that h+ and O2− were responsible for RhB/TC degradation. The mechanism accounting for the observed catalytic activities was discussed according to the band gap structure, DFT calculations and free radicals capture tests.