Defective titanium dioxide single crystals exposed by high-energy {001} facets for efficient oxygen reduction

Abstract

The cathodic material plays an essential role in oxygen reduction reaction for energy conversion and storage systems. Titanium dioxide, as a semiconductor material, is usually not recognized as an efficient oxygen reduction electrocatalyst owning to its low conductivity and poor reactivity. Here we demonstrate that nano-structured titanium dioxide, self-doped by oxygen vacancies and selectively exposed with the high-energy {001} facets, exhibits a surprisingly competitive oxygen reduction activity, excellent durability and superior tolerance to methanol. Combining the electrochemical tests with density-functional calculations, we elucidate the defect-centred oxygen reduction reaction mechanism for the superiority of the reductive {001}-TiO2−x nanocrystals. Our findings may provide an opportunity to develop a simple, efficient, cost-effective and promising catalyst for oxygen reduction reaction in energy conversion and storage technologies.

Breathable Carbon‐Free Electrode: Black TiO2 with Hierarchically Ordered Porous Structure for Stable Li–O2 Battery

“…In case of magnéli Ti 4 O 7 cathode, studied by Nazar and co-workers, the surface of Ti 4 O 7 was revealed to be oxygen-deficient TiO 2−x , and the substoichiometry was maintained even during the exposure to oxygenrich environment. [36,37] Therefore, studies on the air cathode with bulk TiO 2−x seem to be necessary to account for the potential applications of titanium-based materials. The Ti 3+ ions and oxygen vacancies in TiO 2−x are known to trigger various novel properties, including high electrical conductivity [33][34][35] and catalytic activity.…”

Titanium–tantalum oxide as a support for Pd nanoparticles for the oxygen reduction reaction in alkaline electrolytes

“…9. Pei et al ascribed the poorer stability of TiO 2 polycrystals to their anatase-rutile mixed crystal phase [57]. In our case, both the anatase crystallographic structure and the fact of being a semi-crystalline material could be responsible for the poor stability of the titanium-based support.…”

“…It has been proved that the catalytic activity toward the ORR of TiO 2 -based catalysts depends on both the structural properties and the fabrication procedure. For example, spray-deposited anatase and single crystal rutile type TiO 2 exhibit a 4e − pathway in alkaline electrolytes; whereas amorphous titanium oxides exhibit 2e − pathway [32,33] [57]. In our case, doping TiO 2 with Ta creates oxygen vacancies that could contribute to the enhancement of the activity towards the ORR.…”

“…The crystallographic structure of our Ti 0.8 Ta 0.2 O 2 , in the prevalent form of anatase, also contributes to the enhancement of the activity. With an engineered design of the crystallographic orientation of TaTi-oxide crystals, this activity could be further enhanced, as demonstrated by Pei et al [57] or Liu et al [58]. On the other hand, a review conducted by Trasatti et al [59] showed that the activity towards the ORR of noble metals supported on titanium-based supports is increased due to the strong metal support interaction (SMSI) effect, a fact that has been proved by other authors in more recent papers [34,41,60].…”

A one‐step way to novel carbon‐niobium nitride nanoparticles for efficient oxygen reduction

“…The oxygen reduction reaction (ORR) catalysts play an essential role in such devices and have been widely studied by scientists around the world. To accelerate the ORR process, precious Pt‐based catalysts are highly desired, but the limited reserve and increasing price of Pt have become restrictions of such systems . Thus, it makes sense to develop a high efficient Pt‐free ORR catalyst for the update of our energy systems.…”