Hydrogenation Synthesis of Blue TiO₂ for High-Performance Lithium-Ion Batteries

Abstract

Blue hydrogenated rutile TiO 2 nanoparticles (blue TiO 2 ) are prepared by treating white rutile via an enhanced hydrogenation process (i.e., high pressure and temperature). The materials characterization results demonstrate that the hydrogenation process leads to the increase in the unit cell volume and decrease in the size compared with the untreated white TiO 2 . The electrochemical impedance spectra analyses and theoretical energy calculations using density functional theory (DFT) suggest that the hydrogenation process not only improves electronic conductivity due to the formation of oxygen vacancy in the hydrogenation process but also dramatically augments lithium-ion mass transport within the crystalline lattice due to the introduction of oxygen vacancy and crystalline dislocation. Because of these characteristics resulting from the hydrogenation process, the blue TiO 2 based lithium ion batteries (LIBs) possess significantly higher energy capacity and better rate performance than the white TiO 2 based LIBs. In particular, at the rate of 0.1 and 5 C (1 C = 336 mAh g −1 ), the discharge capacities of the blue rutile are maintained at ca.179.8 and 129.2 mAh g −1 , while the capacities of the white TiO 2 are just ca. 119.6 and 55.5 mAh g −1 , respectively.

Preparation of Blue TiO2 for Visible-Light-Driven Photocatalysis

“…These results show that a slight change occurred along the a and b directions, but there was significant expansion in the c direction, and as a result, the unit cell volume expanded significantly as well [10]. Recent publications showed that the morphology of TiO 2 materials resulted in differences of the enhanced photocatalytic activity for the production of hydrogen between the {101} and {001} facets of anatase tetragonal bipyramidal nanocrystals [11][12][13].…”

“…In both structures, the octahedral distortions create the basic building units [7,8]. The lengths and angles of octahedral coordinated Ti atoms, therefore, dictate stacking in both structures, as shown in Figure 1. 3.…”

“…In addition, hydrogenation processes require harsh synthetic conditions and/or a dangerous production process [4,10,19,[21][22][23][24][25]. Therefore, H 2 is introduced using different reducing agents such as NaBH 4 and TiH 2 [4,26,27] instead of an external dose of hydrogen gas.…”

Dual modification of TiO 2 nanorods for selective photoelectrochemical detection of organic compounds

“…1.5 nm. This surface lattice disorder which can be attributed to the hydrogenation treatment could yield mid-gap electronic levels that are responsible for the absorption of broader light wavelengths [27]. While the TiO2 electrode strongly absorbs light only in the UV region due to the large band gap (3.0 eV for rutile), the Au@TiO2 electrode shows another absorption band centered at 560 nm that can be attributed to the typical SPR effect of Au nanoparticles.…”

Modifying oxide nanomaterials’ properties by hydrogenation

“…[25,49,61] Meanwhile, there are a few reports mentioning possible decrease in the photocatalytic activities, if the hydrogenated TiO 2 nanomaterials are not properly prepared. [37,38] So far, hydrogenation has been conducted on TiO 2 nanoparticles, [4,21,31] nanorods, [48] nanotubes, [45] nanowires, [46] nanosheets, [35,36] with anatase or rutile phase, [4,29,33] under high-pressure, [4,21] ambient pressure, [29,30,39] or low-pressure [43] pure hydrogen environment, or hydrogen-argon, [44][45][46][47][48] hydrogen-nitrogen [52][53][54] gas flow, in the temperature range from room temperature [21] to 700°C, [27] with a hydrogenation time from a few minutes [27] to 20 days. [21] With no doubt, we can image that the so-formed TiO 2 nanomaterials will display variations in their characteristics and performances.…”