Recent advances in the synthesis of defective TiO2 nanofibers and their applications in energy and catalysis

TiO2 nanofibers (NFs, <1000 nm) with the merits of one-dimensional (1D) structure, adjustable surface active sites, excellent electro- and photochemical properties, nontoxicity, and low-cost have triggered a huge interest in multiple fields such as catalysis and energy storage. In addition, in comparison with the broadly used nanoparticles, continuous TiO2 NFs with better film-forming property is easy to be recycled. Nevertheless, due to inherent shortcomings like wide bandgap (3.0–3.2 eV) and chemical inertness, their electrochemical and photochemical performance are greatly limited. Compare with TiO2 NFs, black defective TiO2 NFs with surface disordered structure, Ti3+ defects and oxygen vacancy defects exhibit excellent visible light responsiveness and high conductivity making them new research hotspots. In this review, some popular synthesis methods and defect engineering strategies for the fabrication of defective or black TiO2 NFs are first systematically summarized, and then the recent progress associated with applications of defective TiO2 NFs in photocatalysis, electrocatalysis, and electrochemical energy storage and harvest is elaborated in detail. Finally, an insight into the remaining major challenges for the future development of defective TiO2 NFs is proposed. This review serves to provide guidelines for designing high performance and high strength defective TiO2 NFs with promising energy and catalysis applications.