Metal oxynitrides as emerging materials with photocatalytic and electronic properties

Abstract

Oxynitrides of transition metals, alkaline earth metals and rare earth metals are intensively investigated as a group of materials to expand and tune the properties of oxides. The differences in polarizability, electronegativity and anion charge of nitrogen and oxygen induce changes in the physical and chemical properties of oxides by nitrogen introduction. The effects on properties arise from the higher covalency of the metal-nitrogen bond and the changes in the energies of electronic levels, and are important in slightly doped nitrogen metal oxides as in stoichiometric oxynitrides. More intense recent progress in oxynitride research has been made in some specific fields such as photocatalysis in water splitting and other processes as the observed small band gaps lead to activity in the visible light range. The stabilization of new perovskite oxynitrides, with the oxidation states of cations tuned by N/O stoichiometry, has led to new magnetic and dielectric materials. The lower electronegativity of nitrogen and larger crystal field splitting induced by N 3À shifts the emission wavelengths of phosphors to the red, and oxynitridosilicates have been investigated as components of white LEDs.

Metal Oxynitrides as Promising Electrode Materials for Supercapacitor Applications

“…The materials performance of these various categories of materials is relevant for current improvements to technology. For instance with introduction of nitrogen, one typically observes a rise in electronic conductivity (reduction in band gap [64,100] ), improvement in chemical inertness, [101] and enhanced wettability (hydrophilic nature [57] ). [33,38,97] Attempts have been made to reduce leakage currents by the application insulating layer as a blocking layer to an electron at electrode/electrolyte interface.…”

“…[33,38,97] Attempts have been made to reduce leakage currents by the application insulating layer as a blocking layer to an electron at electrode/electrolyte interface. [64,102] Eventually, this results in the reduction of the bandgap of formed oxynitrides, which means an upsurge in electronic conductivity. [98] In addition to these issues, MOs also suffer from cyclic stability and electronic conductivity.…”

“…[64] Such an approach would render this compositional space relevant for other applications too. [64] Such an approach would render this compositional space relevant for other applications too.…”

Preparation of LaTiO2N Using Hydrothermally Synthesized La2Ti2O7 as a Precursor and Urea as a Nitriding Agent

“…Metal oxynitrides have attracted great attention over the past two decades for their promising applications in many fields, such as visible-light-driven photocatalysts, [1][2][3][4][5][6][7][8][9] high-K dielectrics, [10][11][12][13] ferroelectrics, [14][15][16] colossal magnetoresistive materials, [17][18][19] and environmentally friendly inorganic pigments. [20][21][22][23][24] Metal oxynitrides with perovskite-type structure are of particular interest because the incorporation of nitrogen into the oxidic perovskite crystalline structure leads to multifunctional properties as a result of band gap reduction.…”

Structural and electronic structures of alkaline-earth transition metal oxynitride perovskites

“…Comparable DOS are observed overall. For brevity, we will limit our discussion to the electronic structure of the most stable orthorhombic Imma cis-MO 4 77) or LDA with onsite Coulomb interaction (LDA+U) method 78) (cf. Supporting Information) suggest magnetic properties since the spin-up and spin-down DOS and band structures slightly differ around E F .…”