We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

Graphene plasmons were predicted to possess ultra-strong field confinement and very low damping at the same time, enabling new classes of devices for deep subwavelength metamaterials, single-photon nonlinearities, extraordinarily strong light-matter interactions and nano-optoelectronic switches. While all of these great prospects require low damping, thus far strong plasmon damping was observed, with both impurity scattering and many-body effects in graphene proposed as possible explanations. With the advent of van der Waals heterostructures, new methods have been developed to integrate graphene with other atomically flat materials. In this letter we exploit near-field microscopy to image propagating plasmons in high quality graphene encapsulated between two films of hexagonal boron nitride (h-BN). We determine dispersion and particularly plasmon damping in real space. We find unprecedented low plasmon damping combined with strong field confinement, and identify the main damping channels as intrinsic thermal phonons in the graphene and dielectric losses in the h-BN. The observation and in-depth understanding of low plasmon damping is the key for the development of graphene nano-photonic and nano-optoelectronic devices.

Highly confined low-loss plasmons in graphene-boron nitride heterostructures

Lightweight absorption-dominated electromagnetic interference (EMI) shielding materials are more attractive than conventional reflection-dominated counterparts because they minimize the twice pollution of the reflected electromagnetic (EM) wave. Here, porous Ti2CT x MXene/poly(vinyl alcohol) composite foams constructed by few-layered Ti2CT x (f-Ti2CT x) MXene and poly(vinyl alcohol) (PVA) are fabricated via a facile freeze-drying method. As superior EMI shielding materials, their calculated specific shielding effectiveness reaches up to 5136 dB cm2 g-1 with an ultralow filler content of only 0.15 vol % and reflection effectiveness (SER) of less than 2 dB, representing the excellent absorption-dominated shielding performance. Contrast experiment reveals that the good impedance matching derived from the multiple porous structures, internal reflection, and polarization effect (dipole and interfacial polarization) plays a synergistic role in the improved absorption efficiency and superior EMI shielding performance. Consequently, this work provides a promising MXene-based EMI shielding candidate with lightweight and high strength features.

Lightweight Ti2CTx MXene/Poly(vinyl alcohol) Composite Foams for Electromagnetic Wave Shielding with Absorption-Dominated Feature

Active modulation of electromagnetically induced transparency analogue in terahertz hybrid metal-graphene metamaterials

Synthesis of fish skin-derived 3D carbon foams with broadened bandwidth and excellent electromagnetic wave absorption performance

Facile synthesis of hierarchical chrysanthemum-like copper cobaltate-copper oxide composites for enhanced microwave absorption performance.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1289&context=ameslab_manuscripts

Graphene Plasmonics: A Platform for 2D Optics

Goos–Hanchen (G–H) effect is of great interest in the manipulation of optical beams. However, it is still fairly challenging to attain efficient controls of the G–H shift for diverse applications. Here, a mechanism to realize tunable G–H shift in the terahertz regime with electrically controllable graphene is proposed. Taking monolayer graphene covered epsilon-near-zero metamaterial as a planar model system, it is found that the G–H shifts for the orthogonal s-polarized and p-polarized terahertz beams at oblique incidence are positive and negative, respectively. The G–H shift can be modified substantially by electrically controlling the Fermi energy of the monolayer graphene. Reversely, the Fermi energy dependent G–H effect can also be used as a strategy for measuring the doping level of graphene. In addition, the G–H shifts of the system are of strong frequency-dependence at oblique angles of incidence, therefore the proposed graphene hybrid system can potentially be used for the generation of terahertz “rainbow,” a flat analog of the dispersive prism in optics. The proposed scheme of hybrid system involving graphene for dynamic control of G–H shift will have potential applications in the manipulation of terahertz waves.

Electrically Tunable Goos–Hänchen Effect with Graphene in the Terahertz Regime

Enhanced low-frequency microwave absorbing property of SCFs@TiO2 composite

Artificially constructed metamaterials or metasurfaces with tailored resonant elements provide a revolutionary platform for controlling light at the subwavelength scale. Switchable or frequency-agile meta-devices are highly desirable in achieving more flexible functionalities and have been explored extensively by incorporating various materials, which respond to external stimuli. Graphene, a two-dimensional material showing extraordinary physical properties, has been found very promising for tunable meta-devices. However, the high intrinsic loss of graphene severely obstructs us from achieving high-quality resonance in various graphene metamaterials and metasurfaces, and the loss compensation can be considered as a straightforward strategy to take further advantages of enhanced light–graphene interactions. Here, we demonstrate that the photoexcited graphene, in which the quasi-Fermi energy of graphene changes corresponding to optical pumping, can boost the originally extremely weak magnetic resonance in a...

Quanhong Fu

Papers

Facile synthesis of hierarchical chrysanthemum-like copper cobaltate-copper oxide composites for enhanced microwave absorption performance.

Graphene Plasmonics: A Platform for 2D Optics

Electrically Tunable Goos–Hänchen Effect with Graphene in the Terahertz Regime

Enhanced low-frequency microwave absorbing property of SCFs@TiO2 composite

Photoexcited Graphene Metasurfaces: Significantly Enhanced and Tunable Magnetic Resonances