Advanced Fabrication of Chemically Bonded Graphene/TiO₂ Continuous Fibers with Enhanced Broadband Photocatalytic Properties and Involved Mechanisms Exploration

In this article, a novel route for the synthesis of graphene/TiO₂ continuous fibers (GTF) using force-spinning combined with water vapor annealing method is reported for the first time. The morphology, structure and optical properties of the composite were fully characterized. With a single step of heat treatment process using steam at ambient conditions, we were able to initiate a series of chemical reactions, such as reduction of graphene oxide (GO), crystallization of TiO₂, formation of C-Ti bond, and introduction of oxygen vacancies into TiO₂. The incorporation of graphene in TiO₂ fibers facilitated bandgap narrowing and improved photo-induced charge separation in the photocatalyst. As a result of synergistic effects, TiO₂ fibers-2 wt% graphene (2%GTF) showed the highest photocatalytic activities in the degradation of X-3B under UV irradiation, superior to the benchmark photocatalyst P25. Under visible light irradiation, the same catalyst was about 4 times more efficient compared to pure TiO₂ fibers (PTF). A detailed study of involved active species (in particular, ·, h⁺ and ·OH) unraveled the mechanism regarding photocatalysis.