The Vickers hardness of boron suboxide single crystals was measured using a diamond indentation method. Under a loading force of 0.98 N, our test gave an average Vickers hardness of 45 GPa. The average fracture toughness was measured as 4.5 MPa m1/2. We also measured the hardness of the cubic boron nitride and sapphire single crystals for comparison. The average measured hardness for boron suboxide was found to be very close to that of cubic boron nitride under the same loading force. Our results suggest that the boron suboxide could be a new superhard material for industrial applications, surpassed in hardness only by diamond and cubic boron nitride.

We report here the high-pressure synthesis of well-sintered millimeter-sized bulks of superhard BC 2 N and BC 4 N materials in the form of a nanocrystalline composite with diamond-like amorphous carbon grain boundaries. The nanostructured superhard B-C-N material bulks were synthesized under high P-T conditions from amorphous phases of the ball-milled molar mixtures. The synthetic B-C-N samples were characterized by synchrotron x-ray diffraction, high-resolution transmission electron microscope, electron energy-loss spectra, and indentation hardness measurements. These new high-pressure phases of B-C-N compound have extreme hardnesses, second only to diamond. Comparative studies of the high P-T synthetic products of BC 2 N, BC 4 N, and segregated phases of diamond + cBN composite confirm the existence of the single B-C-N ternary phases.

The authors demonstrate a substantial enhancement in radiation-induced amorphization resistance for single-phased nanocrystalline (NC) versus large-grained polycrystalline MgGa2O4. NC and large-grained MgGa2O4 were irradiated at ∼100K with 300keV Kr++ ions to fluences ranging between 5×1019 and 4×1020Kr∕m2. Large-grained MgGa2O4 samples began to amorphize by a fluence of 5×1019Kr∕m2, while NC MgGa2O4 remained crystalline with no evidence for structural changes (other than moderate grain growth in the lowermost implanted region), to a fluence of 4×1020Kr∕m2. To our knowledge, this is the first experimental study to reveal enhanced amorphization resistance in an irradiated, single-phase, NC material.

Developing substitutes of noble metal catalysts toward oxygen reduction reaction (ORR) at the cathode is of vital importance for promoting low‐temperature polymer electrolyte membrane fuel cells. Transition metal species have been one of the hot areas of interest due to their low cost, high activity, and long‐term stability. The design of porous carbon nanostructures decorated with transition metal species plays a vital role in enhancing ORR catalytic performance. Here, the recent breakthroughs in porous carbon nanostructures decorated with transition metal species (including nanoparticles and atomically dispersed supported metal) are discussed. The porous nanostructures can provide large surface area as well as abundant pore channels, leading to sufficient exposure of active sites and efficient mass transfer. These nanostructures can be synthesized by several approaches, including the templated method, the self‐templated method, the impregnation process, and so on. Furthermore, the ORR performance and the exploration of active sites are also discussed for further enhancement of the ORR catalysts. Finally, the challenges and prospects are discussed, which would push forward the development of ORR catalysts in the near future.

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SnO2@CF was obtained by anchoring SnO2 nanoparticles on carbon foam, which exhibited superior electrochemical performance for K+ storage.

The development of aqueous Zn metal batteries (AZMBs) is impeded by severe corrosion, H2 evolution, and dendrite formation issues. In addition, the inability of AZMBs to achieve a large capacity also hinders their commercialization. Here, a multifunctional ZnSe protective layer is reported to synchronously solve the above issues. The ZnSe layer can efficiently provide anticorrosion while also suppressing hydrogen evolution. Systematic analyses of the mechanism suggest that the low Zn affinity of ZnSe and the unbalanced charge distribution at the interface can promote a uniform distribution of Zn2+ and accelerate Zn2+ migration, thus realizing dendrite‐free behavior. Therefore, the Zn@ZnSe symmetric cell exhibits notable rate performance and cycling stability (1500 h). Moreover, this symmetric cell can still stabilize with a low polarization (50 mV), even at 10 mA cm−2 with 5 mAh cm−2. The full cell paired with MnO2 achieves a long lifespan (1800 cycles) with a Coulombic efficiency near 100%. Therefore, this strategy for eliminating dendrites and side reactions at a high rate with a large capacity provides a promising solution for the development of AZMBs.

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