A novel Ti-doped Sm–Mn mixed oxide (TiSmMnO x ) was first designed for the selective catalytic reduction (SCR) of NO x with NH3 at a low temperature. The TiSmMnO x catalyst exhibited a superior catalytic performance, in which NO x conversion higher than 80% and N2 selectivity above 90% could be achieved in a wide-operating temperature window (60–225 °C). Specially, the catalyst also showed high durability against the large space velocity and excellent SO2/H2O resistance. Ti incorporation can efficiently inhibit MnO x crystallization and tune the MnO x phase during calcination at a high temperature. Subsequently, a high specific surface area as well as an increased amount of acid sites on the TiSmMnO x catalysts were produced. Further, the reducibility of the Sm-doped MnO x catalyst was modulated, facilitating NO oxidation and inhibiting NH3 nonselective oxidation. Consequently, a superior SCR activity was achieved at a low temperature and the operating temperature window of the TiSmMnO x catalyst was significantly widened. These findings may provide new insights into the reasonable design and development of the new non-vanadium catalysts with a high NH3-SCR activity for industrial application.

A large number of oxides that adopt the centrosymmetric (CS) garnet-type structure (space group Ia3̅ d) have been widely studied as promising magnetic and host materials. Hitherto, no noncentrosymmetric (NCS) garnet has been reported yet, and a strategy to NCS garnet design is therefore significant for expanding the application scope. Herein, for the series A 3 A′ 3 Zn 6 Te 4 O 24 (A = Na, A′ = La, Eu, Nd, Y, and Lu), we demonstrated that the structural symmetry evolution from CS Ia3̅ d (A′ = La) to NCS I4 1 22 (A′ = Eu, Nd, Y, and Lu) could be achieved due to the A-site cationic ordering-driven inversion symmetry breaking. Na 3 A′ 3 Zn 6 Te 4 O 24 (A′ = rare earth) are the first garnets that possess NCS structures with A-site cationic ordering. Diffuse reflectance spectra and theoretic calculations demonstrated that all these NCS garnets are indirect semiconductors. Moreover, their potential applications as host materials for red phosphors and Na-ion conductors were also investigated in detail, which firmly confirmed the NCS structure and A-site cationic ordering. Our findings have paved the way to design NCS or even polar garnets that show intriguing functional properties, such as ferroelectricity, multiferroicity, and second harmonic generation.

No abstract

No abstract