Reversible oxygen scavenging at room temperature using electrochemically reduced titanium oxide nanotubes

Abstract

A material capable of rapid, reversible molecular oxygen uptake at room temperature is desirable for gas separation and sensing, for technologies that require oxygen storage and oxygen splitting such as fuel cells (solid-oxide fuel cells in particular) and for catalytic applications that require reduced oxygen species (such as removal of organic pollutants in water and oil-spill remediation). To date, however, the lowest reported temperature for a reversible oxygen uptake material is in the range of 200-300 °C, achieved in the transition metal oxides SrCoOx (ref. 1) and LuFe₂O(4+x) (ref. 2) via thermal cycling. Here, we report rapid and reversible oxygen scavenging by Ti(2-x) nanotubes at room temperature. The uptake and release of oxygen is accomplished by an electrochemical rather than a standard thermal approach. We measure an oxygen uptake rate as high as 14 mmol O₂ g(-1) min(-1), ∼2,400 times greater than commercial, irreversible oxygen scavengers. Such a fast oxygen uptake at a remarkably low temperature suggests a non-typical mechanistic pathway for the re-oxidation of Ti(2-x). Modelling the diffusion of oxygen, we show that a likely pathway involves 'exceptionally mobile' interstitial oxygen produced by the oxygen adsorption and decomposition dynamics, recently observed on the surface of anatase.

Synthesis of Antimony Nanotubes via Facile Template-Free Solvothermal Reactions

“…2a), which suggests that the formation of Sb nanotube mainly depends on its lamellar structure. The similar results have been previously reported [6–9]. Compared with the original sample, the filtered and rinsed sample exhibits relatively neat and uniform tubular structures without the clustered phenomenon in Fig.…”

Oxygen Scavengers Based on Titanium Oxide Nanotubes for Packaging Applications

“…An absorption curve can be found elsewhere. 4 The results in this study contrast previous reports on the use of nanostructured titania as an oxygen scavenger or oxygen indicator. 9,10 In 2004, Xiao-e and coworkers reported the rapid reaction (over minutes, roughly similar timescales than the reaction rates reported here) of the residual dissolved oxygen in argon purged acetonitrile.…”

“…At this point, the reduction process can be repeated making it a reversible process. 4 Anodization. Titanium dioxide nanotubes were fabricated electrochemically by anodizing 99.7% titanium foil (127 um thick.…”

Electric-field control of tri-state phase transformation with a selective dual-ion switch

“…Among all the possible anions and cations, the oxygen and hydrogen ions provide the most accessible and effective pathways for inducing the phase transformation with novel electronic and magnetic properties. Although this transformation can be achieved conventionally with thermal annealing [12][13][14][15][16][17][18] , the electric field control has unique advantages due to its excellent accessibility and tunability with extended functionalities [4][5][6][7][8] . In recent years, the electronic-field controllable ionic liquid gating (ILG) has emerged as an attractive controlling knob for manipulating material properties not only through well-established electrostatic doping [19][20][21] , but also by inducing phase transformation with ion transfer through its intrinsic electrochemical effect 22 .…”