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A bound state in the continuum (BIC) metasurface (MS) was designed to achieve an ultrahigh quality factor(Q factor) using natural hyperbolic materials, such as hexagonal boron nitride. To investigate the structure's dispersion and Q factor, a unit cell of the MS comprising semicircles and rectangles was designed. This MS structure supports symmetry-protected BICs and exhibits a Q factor of approximately 13 000 at 4.43964 × 1013 Hz. By breaking the MS symmetry, the BICs are converted into quasi-BICs, resulting in quasi-BIC resonance with a high Q factor. Further analysis of the reflection spectra and multipole theory indicates that the toroidal dipole (TD) has the most significant influence on the resonance. Thus, the symmetry-protected BIC can be transformed into the TD resonance with a Q factor by breaking symmetry. [ABSTRACT FROM AUTHOR]

Molybdenum oxide (MoO3) has become a potential anode material for lithium-ion batteries due to high theoretical capacity and environmental friendliness. Nonetheless, MoO3 suffers from serious capacity fading caused by severe pulverization and lower electronic conductivity. Herein, the carbon nanotubes (CNTs) are embedded in α-MoO3 nanoribbons via a facile one-step hydrothermal process. The synergistic effect of α-MoO3 and CNTs can effectively alleviate the volume expansion of α-MoO3 and dominated Li+ storage properties. As a result, the flexible α-MoO3/CNTs composite exhibits excellent rate capability compared with the original α-MoO3, as well as a reversible capacity of 270 mAh/g after 250 cycles. [ABSTRACT FROM AUTHOR]

Recent experimental studies have shown that the FePt nanoparticles (NPs) assembled on graphene exhibit enhanced durability and catalytic activity for oxygen reduction reaction (ORR) than Pt-only catalysts. In this work, we have performed density functional theory calculations to investigate the stability and reactivity of several FePt NPs deposited on defective graphene for ORR, where n is adopted as 0, 1, 2, and 3, respectively. The results indicate that the alloying between Fe and Pt can enhance the stability of NPs and promote their oxygen reduction activity. Moreover, the monovacancy site in the graphene can provide anchoring sites for these bimetallic NPs by forming strong metal-substrate interaction, ensuring their high stability. Importantly, the O adsorption on these composites is weakened in various ways, which is ascribed to the change in their averaged d-band center. Thus, these composites exhibit superior catalytic performance in ORR by providing a balance in the O binding strength that allows for enhanced turnover. Our results may be useful to unravel the high stability and reactivity of defective graphene-FePt NPs for ORR from a theoretical perspective. [ABSTRACT FROM AUTHOR]