Orderly defective superstructure for enhanced pseudocapacitive storage in titanium niobium oxide

Artificial defect engineering in transition metal oxides is of important terms for numerous applications. In the present work, we proposed an in-situ gas reduction strategy to introduce ordered defects into titanium niobium oxide embedding on vapor grew carbon fibers (Ti2Nb10O29−x@VGCFs). High-resolution transmission electron microscopy (HRTEM) and fast Fourier transform (FFT) simulation indicate that the ordered oxygen defects locate at interval layers, which leads to a new superstructure in Ti2Nb10O29. The ordered defects could provide extra active sites for lithium-ion storage and modulate ionic migration, resulting an enhanced pseudocapacitive performance. In addition, the excellent structural stability of the superstructure was proved by in-situ HRTEM under a harsh electrochemical process. Our work provides a directly observation of orderly defective superstructure in transition metal oxide, and its functionality on electrochemistry was revealed.