Ceria nanocrystallites with different morphologies and crystal planes were hydrothermally prepared, and the effects of ceria supports on the physicochemical and catalytic properties of Pd/CeO 2 for the CO and propane oxidation were examined. The results showed that the structure and chemical state of Pd on ceria were affected by ceria crystal planes. The Pd species on CeO 2 -R (rods) and CeO 2 -C (cubes) mainly formed Pd x Ce 1−x O 2−σ solid solution with −Pd 2+ −O 2− −Ce 4+ − linkage. In addition, the PdO x nanoparticles were dominated on the surface of Pd/CeO 2 -O (octahedrons). For the CO oxidation, the Pd/CeO 2 -R catalyst showed the highest catalytic activity among three catalysts, its reaction rate reached 2.07 × 10 −4 mol g Pd −1 s −1 at 50 °C, in which CeO 2 -R mainly exposed the ( 110) and (100) facets with low oxygen vacancy formation energy, strong reducibility, and high surface oxygen mobility. TOF of Pd/CeO 2 -R (3.78 × 10 −2 s −1 ) was much higher than that of Pd/CeO 2 -C (6.40 × 10 −3 s −1 ) and Pd/CeO 2 -O (1.24 × 10 −3 s −1 ) at 50 °C, and its activation energy (E a ) was 40.4 kJ/mol. For propane oxidation, the highest reaction rate (8.08 × 10 −5 mol g Pd −1 s −1 at 300 °C) was obtained over the Pd/CeO 2 -O catalyst, in which CeO 2 -O mainly exposed the (111) facet. There are strong surface Ce−O bonds on the ceria (111) facet, which favors the existence of PdO particles and propane activation. The turnover frequency (TOF) of the Pd/CeO 2 -O catalyst was highest (3.52 × 10 −2 s −1 ) at 300 °C and its E a value was 49.1 kJ/mol. These results demonstrate the inverse facet sensitivity of ceria for the CO and propane oxidation over Pd/ ceria.

The theoretically proposed graphene/single-walled carbon nanotube (G/SWCNT) hybrids by placing SWCNTs among graphene planes through covalent C-C bonding are expected to have extraordinary physical properties and promising engineering applications. However, the G/CNT hybrids that have been fabricated differ greatly from the proposed G/SWCNT hybrids because either the covalent C-C bonding is not well constructed or only multiwalled CNTs/carbon nanofibers rather than SWCNTs are available in the hybrids. Herein, a novel G/SWCNT hybrid was successfully fabricated by a facile catalytic growth on layered double hydroxide (LDH) at a high temperature over 950 °C. The thermally stable Fe nanoparticles and the uniform structure of the calcined LDH flakes are essential for the simultaneously catalytic deposition of SWCNTs and graphene. The SWCNTs and the CVD-grown graphene, as well as the robust connection between the SWCNTs and graphene, facilitated the construction of a high electrical conductive pathway. The internal spaces between the two stacked graphene layers and among SWCNTs offer room for sulfur storage. Therefore, the as obtained G/SWCNT-S cathode exhibited excellent performance in Li-S batteries with a capacity as high as 650 mAh g(-1) after 100 cycles even at a high current rate of 5 C. Such a novel G/SWCNT hybrid can serve not only as a prototype to shed light on the chemical principle of G/CNT synthesis but also as a platform for their further applications in the area of nanocomposites, heterogeneous catalysis, drug delivery, electrochemical energy storage, and so on.

Crystalline high-entropy ceramics (CHC), a new class of solids that contain five or more elemental species, have attracted increasing interest because of their unique structure and potential applications. Up to now, only a couple of CHCs (e.g., high-entropy metal oxides and diborides) have been successfully synthesized. Here, a new strategy for preparing high-entropy metal nitride (HEMN-1) is proposed via a soft urea method assisted by mechanochemical synthesis. The as-prepared HEMN-1 possesses five highly dispersed metal components, including V, Cr, Nb, Mo, Zr, and simultaneously exhibits an interesting cubic crystal structure of metal nitrides. By taking advantage of these unique features, HEMN-1 can function as a promising candidate for supercapacitor applications. A specific capacitance of 78 F g is achieved at a scan rate of 100 mV s in 1 m KOH. In addition, such a facile synthetic strategy can be further extended to the fabrication of other types of HEMNs, paving the way for the synthesis of HEMNs with attractive properties for task-specific applications.