MnO(x) Nanoparticle-Dispersed CeO2 Nanocubes: A Remarkable Heteronanostructured System with Unusual Structural Characteristics and Superior Catalytic Performance.

Understanding the interface-induced effects of heteronanostructured catalysts remains a significant challenge due to their structural complexity, but it is crucial for developing novel applied catalytic materials. This work reports a systematic characterization and catalytic evaluation of MnOx nanoparticle-dispersed CeO2 nanocubes for two important industrial applications, namely, diesel soot oxidation and continuous-flow benzylamine oxidation. The X-ray diffraction and Raman studies reveal an unusual lattice expansion in CeO2 after the addition of MnOx. This interesting observation is due to conversion of smaller sized Ce(4+) (0.097 nm) to larger sized Ce(3+) (0.114 nm) in cerium oxide led by the strong interaction between MnOx and CeO2 at their interface. Another striking observation noticed from transmission electron microscopy, high angle annular dark-field scanning transmission electron microscopy, and electron energy loss spectroscopy studies is that the MnOx species are well-dispersed along the edges of the CeO2 nanocubes. This remarkable decoration leads to an enhanced reducible nature of the cerium oxide at the MnOx/CeO2 interface. It was found that MnOx/CeO2 heteronanostructures efficiently catalyze soot oxidation at lower temperatures (50% soot conversion, T50 ∼660 K) compared with that of bare CeO2 nanocubes (T50 ∼723 K). Importantly, the MnOx/CeO2 heteronanostructures exhibit a noticeable steady performance in the oxidation of benzylamine with a high selectivity of the dibenzylimine product (∼94-98%) compared with that of CeO2 nanocubes (∼69-91%). The existence of a strong synergistic effect at the interface sites between the CeO2 and MnOx components is a key factor for outstanding catalytic efficiency of the MnOx/CeO2 heteronanostructures.

Triphenylphosphine oxide-1-naphthoic acid (1/1).

In the title compound, C18H15OP.C11H8O2, co-crystallization of triphenylphosphine oxide with 1-naphthoic acid yields a supramolecular structure held together by one O-H...O and three C-H...O hydrogen bonds. The O-H...O hydrogen bond [O...O = 2.592 (2) A] has little effect on the O=P bond distance.

Triphenylphosphine oxide-3-chlorobenzoic acid (1/1).

In the title compound, C(18)H(15)OP.C(7)H(5)ClO(2), the triphenylphosphine oxide molecule forms a single directed hydrogen bond with the 3-chlorobenzoic acid molecule, with an O.O=P distance of 2.607 (2) A. The C-Cl and C=O bonds adopt a cisoid conformation in the 3-chlorobenzoic acid molecule.