Highly conductive nano-sized Magnéli phases titanium oxide (TiOx)

Abstract

Despite the strong recent revival of Magnéli phase TiOx as a promising conductive material, synthesis of Magnéli phase TiOx nanoparticles has been a challenge because of the heavy sintering nature of TiO2 at elevated temperatures. We have successfully synthesized chain-structured Magnéli phases TiOx with diameters under 30 nm using a thermal-induced plasma process. The synthesized nanoparticles consisted of a mixture of several Magnéli phases. A post-synthesis heat-treatment was performed to reduce the electrical resistivity without changing the particle morphology. The resistivity of the heat-treated particle was as low as 0.04 Ω.cm, with a specific surface area of 52.9 m2 g−1. The effects of heat-treatment on changes in the crystal structure and their correlation with the electron conductivity are discussed based on transmission electron microscopy images, X-ray diffraction spectra, and X-ray adsorption fine structure spectra. Electrochemical characterization using cyclic voltammetry and potentiodynamic scan shows a remarkable electrochemical stability in a strongly oxidizing environment.

Modified Synthesis Strategies for the Stabilization of low n TinO2n–1 Magnéli Phases

“…We could not find any work where free‐standing nanoparticles of pure metal‐doped Ti 4 O 7 ‐related Magnéli phases were directly produced. This would allow the determination, at atomic level, of how these complex structures are oriented in the nanoparticles.…”

“…Several synthetic methods have also been applied to the production of nanostructured reduced titanium oxides. While most of these techniques reduce TiO 2 to substoichiometric state like MOCVD, laser irradiation or pulsed laser deposition, there are other strategies that produce directly Magnéli phases nanoparticles like the combustion of organometallic precursors using a diffusion flame aerosol or a plasma . All these synthetic routes provide good control over particle size and shape, and are able to produce monodisperse samples besides the incorporation of other elements as dopants.…”

Electrochemical properties of TiOx/rGO composite as an electrode for supercapacitors

“…The results showed that the TiO x nanoparticle-based electrode had a good cyclability and a stable performance aer 1000 cycles during cyclic voltammetry and hence potential to be applied in supercapacitor. 26 The electrochemical conductivity of TiO x nanoparticles was reported to be depending on the composition of the Magnéli phase which constitutes the TiO x . The effect of Magnéli phase composition on the overall rGO/TiO x electrochemical properties is yet to be investigated.…”

Size Control of Ti4O7 Nanoparticles by Carbothermal Reduction Using a Multimode Microwave Furnace

“…For all these applications, it is necessary to synthesize single-phase Ti 4 O 7 nanomaterials with a high specific surface area [4]. In previous works, Magnéli phase nanoparticles were synthesized using different methods, such as calcination of titanium ethoxide and polyethylene glycol solution [17], thermal plasma treatment of H 2 TiO 3 under Ar/H 2 [18], sol-gel and calcination [19], sol-gel and vacuum-carbothermic processes [20], pulsed UV laser irradiation [21], and thermal-induced plasma processes [22]. In addition, Zhang O 7 at 1050 • C under a hydrogen atmosphere [23], but the fibers sintered and became submicron chains.…”