A Facile Method to Improve the Photocatalytic and Lithium‐Ion Rechargeable Battery Performance of TiO₂ Nanocrystals

Abstract

TiO2 has been well studied as an ultraviolet (UV) photocatalyst and electrode material for lithium‐ion rechargeable batteries. Recent studies have shown that hydrogenated TiO2 displayed better photocatalytic and lithium ion battery performances. Here it is demonstrated that the photocatalytic and battery performances of TiO2 nanocrystals can be successfully improved with a facile low‐temperature vacuum process. These TiO2 nanocrystals extend their optical absorption far into the visible‐light region, display nanometer‐scale surface atomic rearrangement, possess superoxide ion characteristics at room temperature without light irradiation, show a 4‐fold improvement in photocatalytic activity, and has 30% better performance in capacity and charge/discharge rates for lithium ion battery. This facile method could provide an alternative and effective approach to improve the performance of TiO2 and other materials towards their practical applications.

Elaborately Designed Hierarchical Heterostructures Consisting of Carbon‐Coated TiO2(B) Nanosheets Decorated with Fe3O4 Nanoparticles for Remarkable Synergy in High‐Rate Lithium Storage

“…Figure 4 a displays a typical Ti 2p core-level XPS spectrum with Ti 2p 3/2 and 2p 1/2 peaks at 458.8 and 464.5 eV. [ 18 ] In the binding energy range of 700−740 eV (Figure 4 c), the two peaks at 709.6 and 722.9 eV are assigned to Fe 2p 3/2 and 2p 1/2 orbitals. [ 69 ] Note that there is no satellite peak at ≈719 eV characteristic of maghemite (Fe 2 O 3 ), and the two peaks at 709.6 and 722.9 eV are typical for magnetite (Fe 3 O 4 ).…”

“…[17][18][19][20][21] TiO 2 (B), as an unusual polymorph (bronze-phase) of TiO 2 , is found to have an open-channel structure and display a pseudo-capacitive behavior, thus enabling easier Li + diffusion and faster chargingdischarging capabilities. [ 22 ] Its theoretical capacity (335 mA h g −1 ) therefore significantly surpasses that (≈170 mA h g −1 ) of anatase or rutile TiO 2 , and is comparable to that (372 mA h g −1 ) of graphitic carbons.…”

Ultrathin Anatase TiO2 Nanosheets Embedded with TiO2‐B Nanodomains for Lithium‐Ion Storage: Capacity Enhancement by Phase Boundaries

“…Our anatase/TiO 2 -B biphase AB550 electrode displays better Li-cell performance than most TiO 2 materials, including anatase nanotubes, nanowires, nanodisks, and TiO 2 -B nanotubes. [ 2,15,18,24,39,[55][56][57][58][59][60][61] Compared with those materials, AB550 may not have the advantages of high surface area, small particle size or excellent conductivity, but the unique anatase/TiO 2 -B coherent interfaces contribute an additional lithium storage venue due to a favorable charge separation at the boundary, resulting in good lithium storage performance. Specifi cally, at the rates lower than 1500 mAh g −1 , the gravimetric capacity for AB550 is higher than the reported 6 nm anatase nanoparticles, 3 nm TiO 2 -B nanoparticles as well as mesoporous TiO 2 -B.…”

Unique Properties of 2 D Layered Titanate Nanosheets as a Building Block for the Optimization of the Photocatalytic Activity and Photostability of TiO2‐Based Nanohybrids

“…However, most of TiO 2 -based hybrid photocatalysts reported thus far are synthesized by crystal growth of narrow bandgap semiconductor on the surface of TiO 2 0D microcrystals/nanocrystals, instead of 2D nanosheets. [12][13][14][15] For the development of breakthrough technology in solar energy conversion, it is very important to investigate the effects of the 2D layered TiO 2 nanosheets as a building block for efficient TiO 2 -based hybrid photocatalysts because most of visible light active photocatalysts with high quantum efficiency can be synthesized by hybridization of titanium oxide and narrow bandgap semiconductor. [16][17][18] Several TiO 2 -based hybrid photocatalysts have been reported, [12,19,20] but to the best of our knowledge, we are aware not of comparative and systematic investigations on layered titanate 2D nanosheets as a building block for hybrid-type photocatalysts.…”