Oxygen Vacancies Evoked Blue TiO₂(B) Nanobelts with Efficiency Enhancement in Sodium Storage Behaviors

Abstract

Oxygen vacancies (OVs) dominate the physical and chemical properties of metal oxides, which play crucial roles in the various fields of applications. Density functional theory calculations show the introduction of OVs in TiO2(B) gives rise to better electrical conductivity and lower energy barrier of sodiation. Here, OVs evoked blue TiO2(B) (termed as B‐TiO2(B)) nanobelts are successfully designed upon the basis of electronically coupled conductive polymers to TiO2, which is confirmed by electron paramagnetic resonance and X‐ray photoelectron spectroscopy. The superiorities of OVs with the aid of carbon encapsulation lead to higher capacity (210.5 mAh g−1 (B‐TiO2(B)) vs 102.7 mAh g−1 (W‐TiO2(B)) at 0.5 C) and remarkable long‐term cyclability (the retention of 94.4% at a high rate of 10 C after 5000 times). In situ X‐ray diffractometer analysis spectra also confirm that an enlarged interlayer spacing stimulated by OVs is beneficial to accommodate insertion and removal of sodium ions to accelerate storage kinetics and preserve its original crystal structure. The work highlights that injecting OVs into metal oxides along with carbon coating is an effective strategy for improving capacity and cyclability performances in other metal oxide based electrochemical energy systems.

1D Nanomaterials: Design, Synthesis, and Applications in Sodium–Ion Batteries

“…d) Cycling performance and e) rate performances of W–TiO 2 (B) and B–TiO 2 (B). Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

Heterostructured TiO2 Spheres with Tunable Interiors and Shells toward Improved Packing Density and Pseudocapacitive Sodium Storage

“…[13] Particularly, the enlarged XRD curves of TiO 2 -YB and TiO 2 -HS are made comparisons with the standard peaks of monoclinic bronze-phase (TiO 2 (B), JCPDS 46-1237). [35] As shown in Figure S5b,c of the Supporting Information, some characteristic peaks at 28.6° (0 0 2), 29.7° (−4 0 1), 29.9° (1 1 1), 43.5° (0 0 3), and 44.5° (−6 0 1) are reflected as weak peaks located at the XRD curves of TiO 2 -YB and TiO 2 -HS. These facts are also consistent with the previously discussed results based on HRTEM image.…”

“…[20,24] In addition, the TiO 2 -S electrode displays typical battery-like galvanostatic profiles, indicating the limited surface-controlled charge storage. [28,[35][36][37][38][39][40] On the other side, cycling properties of the different TiO 2 anodes at constant currents are also tested in detail. As can be seen, the specific capacities of TiO 2 -HS are similar with that of TiO 2 -YB, but much larger than that of TiO 2 -S at lower current densities.…”

“…After the first several cycles, the curves illustrate apparent high voltage plateaus and become well overlapped, suggesting much safer sodium storage by avoiding the dendritic growth, as well as favorable capacity reversibility. [24][25][26][27][28][29][35][36][37][38][39][40] The irreversible loss of capacity in these anodes can in some cases be offset by prelithiation/sodiation technologies. [41,42] Figure 3d demonstrates the cycling properties of the three as-prepared TiO 2 samples at low rate of 0.2 A g −1 .…”

Engineering oxygen vacancy on rutile TiO2 for efficient electron-hole separation and high solar-driven photocatalytic hydrogen evolution

“…Because the rutile TiO 2 is extremely stable thermodynamically and has less surface defects than the anatase TiO 2 , constructing rutile TiO 2 with surface defects is promising to have enhanced photocatalytic activity. Surface oxygen vacancy (V O ), as one of the most important surface defects of TiO 2 , receives extensive attention [31][32][33][34][35]. Too low or high content of V O defects are not conducive to narrowing the bandgap and improving the separation efficiency of photogenerated electron-hole pairs.…”