Yixing Li

High-Magnetization FeCo Nanochains with Ultrathin Interfacial Gaps for Broadband Electromagnetic Wave Absorption at Gigahertz

Superparamagnetic FeCo nanochains consisting of assembled ∼25 nm nanoparticles and ∼1 nm gaps are synthesized by facial wet-chemical route and exhibit significant electromagnetic absorption at gigahertz. Both the dielectric and magnetic loss factors present dual-resonance behaviors at 2-18 GHz frequencies, originated from the asymmetric architecture of the cubic FeCo particles that assembled in a one-dimensional chain structure. Theoretical analyses uncover that the origins of the enhancement of electromagnetic losses are ascribed to the high magnetization (228 emu/g) and the ultrathin gaps (∼1 nm), which enhances the Snoek limit and induces anisotropic dielectric polarizations, consequently constructing a proper electromagnetic match.

Confined Au Nanoclusters into High-defective Graphitic Layers for Enhancing the Methanol Electro-oxidation Reaction

The development of a highly efficient catalyst possessing both high activity and remarkable stability is a major focus in fuel‐cell applications. Herein, we utilized an arc‐discharge approach with an ultrafast cooling system to synthesize a core@shell structural Au@C nanocomposite comprising 3–5 nm gold clusters confined within highly defective graphitic layers. Such a construction not only improves the conductivity to accelerate the penetration of ions and electrons during the electrocatalytic process of methanol molecules, but it also suppresses chemical/thermal coarsening of the gold clusters. More importantly, the atomic‐scale Au/C interfaces contribute to a synergistic effect and enhance the activity relative to that of other gold‐based catalysts in the electrooxidation of methanol. This work highlights the role of heterogeneous interfaces in the catalytic efficiency of precious‐metal catalysts and rationalizes optimization in catalyst engineering.

Ultralight and ultraelastic sponge/Al@Al2O3 nanocomposite with tunable electromagnetic properties

Electromagnetic absorption/shielding materials are highly desirable for high-rapidly developing microelectronic devices. However, there is still a lack of specific materials with dynamic tunable properties to solve issues in complex environments. We herein report a hybrid composite consisting of three-dimensional porous melamine sponge and core@shell Al@Al2O3 nanoparticles, possessing multiple merits of low density (12.47 mg/cm3) and high elasticity. By compressing/decompressing the hybrid, the electromagnetic performances can be reversibly tuned between 18 and 26.5 GHz, ascribed to the tunable conductivity raised from the three-dimensional continuous conductive paths. The present work provides a concept for the design of “dynamic” electromagnetic materials.