Flexible, cuttable, origami-enabling ceramic nanofiber mat for visible light-driven catalysts

Despite possessing abundant potential, the brittleness of oxide ceramic nanofibers limits their use in self-standing flexible photocatalysts with easy separation/recycling and customized shaping. Here, we have reported a novel flexible ceramic constructed using electrospinning of metal oxide nanofiber mats of two different phases (CeO₂–TiO₂ [CTO]) with controllable composition. Although pure TiO₂ and CeO₂ nanofibers are too brittle to endure bending, CTO nanofibers show enhanced mechanical properties that make them flexible, bendable, cuttable, and origami-enabled. To study mechanical resilience and nanofiber structures, we have made a series of CTO nanofiber mats with different ratios of TiO₂ and CeO₂. The results reveal that the heterogeneous TiO₂ and CeO₂ interface creates stress transfer pathways, while the amorphous TiO₂ phase absorbs stress. The CTO nanofiber mats can act as an efficient photocatalyst for the degradation of organic pollutants under visible light. The photocatalytic activity of the oxide ceramic mats is closely related to energy band positions and Ce³⁺ content. The decrease in the band gap of the CTO nanofiber mats enables the absorption of visible light, and the conduction band is positioned adequately to produce oxygen radicals via electron transfer. Consequently, the efficient degradation of organic pollutants can be achieved in the presence of the CTO nanofiber mat under visible light. Furthermore, the CTO nanofiber mats are coated with other metal oxides to form p–n junction band structures, which facilitate the separation of holes and electrons, resulting in even higher catalytic activity.