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Titanium reduced oxides TiO2–x occupy, since long time, a prominent place on the landscape of binary metal oxides because of their intriguing ability to form extended defects that affect both the formation of new superlattices and different electronic behaviours. Related to these features, a wide range of practical applications has been achieved. Moved by the conviction of the great potential of understanding the influence of the reactivity, compositional variations and size effects on their functional properties, the aim of this personal account is the optimization of a recently developed strategy for the stabilization of low n TinO2n–1 terms. In particular, we will focus on the Ti4O7 composition as well as the incorporation of transition metals, like Mn, in order to deal with new reduced Magnéli phases., Depto. de Química Inorgánica, Fac. de Ciencias Químicas, TRUE, pub

Contrary to molecular species, only very few solids are reported to host manganese (V) species. Herein, we report three new compounds with a hydroxyapatite structural backbone built on the MnVO4 3− anion: Sr5[(Mn1−xSix)O4]3(OH)1−3x (x = 0 and 0.053), Sr5(MnO4)3(OH)1−yFy (y = 0.90), and Sr5[(Mn1−xSix)- O4]3F1−3x (x = 0.058). These solids are fully characterized using powder X-ray and neutron powder diffraction, scanning transmission electron microscopy, electron energy loss spectroscopy (EELS), thermogravimetric analysis, and magnetic measurements. Especially, we report for the first time EELS Mn−L2,3 spectra of manganese with the oxidation state (V). Contrary to other Mn(V) oxides, these solids and the nominal compound Sr5(MnO4)3OH do not comprise Ba2+ cations but rely only on Sr2+ cations, showing that barium is not a required element to stabilize Mn(V) species in inorganic solids. We show that by tuning soft chemistry conditions on the one hand and post-treatment topological transformation conditions on the other hand, Mn(V) and hydroxyl groups can be substituted by Si(IV) and fluoride ions, respectively. Hence, we deliver solids with a potentially wide composition range. These compounds show significant oxygen anionic conduction, thus suggesting the emergence of new functional materials built from high-oxidation state manganese cations., Depto. de Química Inorgánica, Fac. de Ciencias Químicas, TRUE, pub

In this work we report a synthetic pathway to two-dimensional nanostructures of high oxidation state lamellar cobalt oxides with thicknesses of only few atom layers, through the combined use of precipitation in basic water at room temperature and gentle solid state topotactic transformation at 120 °C. The 2D nanomaterials are characterized by X-ray diffraction, nitrogen porosimetry, scanning electron microscopy, transmission electron microscopy and especially scanning transmission electron microscopy coupled to energy dispersive X-ray analysis and electron energy loss spectroscopy to assess the composition of the nanosheets and the oxidation state of the transition metal species. We show that the nanosheets preserve high oxidation states Co3+ and Co4+ of high interest for electrocatalysis of the oxygen evolution reaction (OER). By combining high Co oxidation state, surface-to-volume ratio and optimized nickel substitution, the 2D nanomaterials produced in a simple way exhibit high OER electrocatalytic activity and stability in alkaline aqueous electrolyte comparable to standard materials obtained in harsh thermal conditions., Depto. de Química Inorgánica, Fac. de Ciencias Químicas, TRUE, pub

New insights into the chemical and structural features of iron or titanium-doped KxMnO2 hollandites are reported. Neutron diffraction and atomically resolved transmission electron microscopy elucidate the localization of the dopant cations that could be one of the key factors governing the functional activity of these nanomaterials, Depto. de Química Inorgánica, Fac. de Ciencias Químicas, TRUE, pub