Search Results (5)

In this study, platinum (Pt) nanocatalysts were synthesized via a sol-gel method over the non-stoichiometric, Magnéli phase titanium oxides (TinO_2n−1) at varying Pt loadings (10–40 wt.%). Their structural and morphological properties were characterized, and after preliminary electrochemical screening, the catalysts were integrated into commercially available gas diffusion electrodes (GDEs) with a three-layer structure to enhance mass transport and catalyst utilization. Membrane electrode assemblies (MEAs) were fabricated using a Nafion^® 117 polymer membrane and tested in a laboratory PEM cell under controlled conditions. The electrochemical activity toward the hydrogen reduction reaction (HRR) was evaluated at room temperature and at elevated temperatures to determine the catalytic efficiency and stability. The optimal Pt loading was determined to be 30 wt.%, achieving a current density of approximately 0.12 A cm⁻² at 0.25 V, demonstrating a balance between catalyst efficiency and material utilization. The chronoamperometry tests showed minimal degradation over prolonged operation, suggesting that the catalysts were durable. These findings highlight the potential of Pt-based catalysts supported on Magnéli phase titanium oxides (TinO_2n−1) for efficient HRRs in electrochemical hydrogen pumps/compressors, offering a promising approach for improving hydrogen compression efficiency and advancing sustainable energy technologies. Full article

Magnéli phases exhibit significant potential for applications in electronic materials in energy conversion due to their high electrical conductivity and excellent thermal stability. In this study, single-phase Ti_nO_2n−1 (n = 4, 5, 6) bulk materials were successfully prepared by a combination of the carbothermal reduction of nano-sized rutile TiO₂ and hot-press sintering methods. The relationships between the phase evolution, microstructural features, and thermoelectric performance were investigated systematically. Synchrotron X-ray diffraction (SXRD) and scanning electron microscopy (SEM) analyses revealed that the Ti₄O₇ and Ti₅O₉ materials had single-phase structures with high densities (relative density > 97%) and no obvious grain boundary holes or microcracks. We tested the thermoelectric properties of the Magnéli phases in the temperature range of 300–1100 K. The Magnéli phases exhibited a significant temperature dependence, with peak zT values of 0.17, 0.18, and 0.14 for Ti₄O₇, Ti₅O₉, and Ti₆O₁₁, respectively, at 1100 K. This variation in thermoelectric performance was mainly attributed to the synergistic effect of the oxygen vacancy concentration and the shear surface density on the carrier concentration and lattice thermal conductivity. Furthermore, the Fermi energy levels and electronic thermal conductivity of the Magnéli phases were calculated using the single parabolic band (SPB) model. Full article

Magnéli phase titanium oxides, also called titanium sub-oxides (Ti_nO_2n−1, 4 < n < 9), are a series of electrically conducting ceramic materials. The synthesis and applications of these materials have recently attracted tremendous attention because of their applications in a number of existing and emerging areas. Titanium sub-oxides are generally synthesized through the reduction of titanium dioxide using hydrogen, carbon, metals or metal hydrides as reduction agents. More recently, the synthesis of nanostructured titanium sub-oxides has been making progress through optimizing thermal reduction processes or using new titanium-containing precursors. Titanium sub-oxides have attractive properties such as electrical conductivity, corrosion resistance and optical properties. Titanium sub-oxides have played important roles in a number of areas such as conducting materials, fuel cells and organic degradation. Titanium sub-oxides also show promising applications in batteries, solar energy, coatings and electronic and optoelectronic devices. Titanium sub-oxides are expected to become more important materials in the future. In this review, the recent progress in the synthesis methods and applications of titanium sub-oxides in the existing and emerging areas are reviewed. Full article

Nanostructured titanium compounds have recently been applied in the design of gas sensors. Among titanium compounds, titanium oxides (TiO₂) are the most frequently used in gas sensing devices. Therefore, in this review, we are paying significant attention to the variety of allotropic modifications of titanium oxides, which include anatase, rutile, brukite. Very recently, the applicability of non-stoichiometric titanium oxide (TiO_2−x)-based layers for the design of gas sensors was demonstrated. For this reason, in this review, we are addressing some research related to the formation of non-stoichiometric titanium oxide (TiO_2−x) and Magnéli phase (Ti_nO_2n−1)-based layers suitable for sensor design. The most promising titanium compounds and hetero- and nano-structures based on these compounds are discussed. It is also outlined that during the past decade, many new strategies for the synthesis of TiO₂ and conducting polymer-based composite materials were developed, which have found some specific application areas. Therefore, in this review, we are highlighting how specific formation methods, which can be used for the formation of TiO₂ and conducting polymer composites, can be applied to tune composite characteristics that are leading towards advanced applications in these specific technological fields. The possibility to tune the sensitivity and selectivity of titanium compound-based sensing layers is addressed. In this review, some other recent reviews related to the development of sensors based on titanium oxides are overviewed. Some designs of titanium-based nanomaterials used for the development of sensors are outlined. Full article

In this review article, attention is paid towards the formation of various nanostructured stoichiometric titanium dioxide (TiO₂), non-stoichiometric titanium oxide (TiO_2−x) and Magnéli phase (Ti_nO_2n−1)-based layers, which are suitable for the application in gas and volatile organic compound (VOC) sensors. Some aspects related to variation of sensitivity and selectivity of titanium oxide-based sensors are critically overviewed and discussed. The most promising titanium oxide-based hetero- and nano-structures are outlined. Recent research and many recently available reviews on TiO₂-based sensors and some TiO₂ synthesis methods are discussed. Some promising directions for the development of TiO₂-based sensors, especially those that are capable to operate at relatively low temperatures, are outlined. The applicability of non-stoichiometric titanium oxides in the development of gas and VOC sensors is foreseen and transitions between various titanium oxide states are discussed. The presence of non-stoichiometric titanium oxide and Magnéli phase (Ti_nO_2n−1)-based layers in ‘self-heating’ sensors is predicted, and the advantages and limitations of ‘self-heating’ gas and VOC sensors, based on TiO₂ and TiO_2−x/TiO₂ heterostructures, are discussed. Full article