Heterocyclic pyrrole molecules are in situ aligned and polymerized in the -absence of an oxidant between layers of the 2D Ti3C2Tx (MXene), resulting in high volumetric and gravimetric capacitances with capacitance retention of 92% after 25,000 cycles at a 100 mV s(-1) scan rate.

Pseudocapacitive Electrodes Produced By Oxidant-Free Polymerization of Pyrrole Between the Layers of 2D Titanium Carbide (MXene)

2D MXenes: Electromagnetic property for microwave absorption and electromagnetic interference shielding

Electromagnetic Response and Energy Conversion for Functions and Devices in Low‐Dimensional Materials

Multifunctional Organic–Inorganic Hybrid Aerogel for Self‐Cleaning, Heat‐Insulating, and Highly Efficient Microwave Absorbing Material

Overview of carbon nanostructures and nanocomposites for electromagnetic wave shielding

Graphene has been long sought-after over the past few decades because of its multiple functions and broad applications in various fields, such as energy, information, medicine, military equipments, and aerospace. In particular, it has been significantly reported in electromagnetic wave absorbing and shielding fields, promoting it as the most cutting-edge topic. Herein, we systematically comb the structures and electromagnetic functions of graphene hybrids. We demonstrate the advances in the microwave response mechanism, including relaxation, charge transport, magnetic resonance, and eddy currents, as well as magnetic-dielectric synergistic effects. Furthermore, our review mainly focuses on graphene-dispersed systems, flexible graphene papers, graphene hybrids, and 3D graphene architectures.

Graphene nanohybrids: excellent electromagnetic properties for the absorbing and shielding of electromagnetic waves

Lightweight and high-efficiency microwave absorption materials with tunable electromagnetic properties is a highly sought-after goal and a great challenge for researchers. In this work, a simple strategy of confinedly implanting small NiFe2O4 clusters on reduced graphene oxide is demonstrated, wherein the magnetic clusters are tailored, and more significantly, the electromagnetic properties are highly tuned. The microwave absorption was efficiently optimized yielding a maximum reflection loss of –58 dB and ∼12 times broadening of the bandwidth (at –10 dB). Furthermore, tailoring of the implanted magnetic clusters successfully realized the selective-frequency microwave absorption, and the absorption peak could shift from 4.6 to 16 GHz covering 72% of the measured frequency range. The fascinating performances eventuate from the appropriately tailored clusters, which provide optimal synergistic effects of the dielectric and magnetic loss caused by multi-relaxation, conductance, and resonances. These findings open new avenues for designing microwave absorption materials in future, and the well-tailored NiFe2O4-rGO can be readily applied as a multi-functional microwave absorption material in various fields ranging from civil and commerce to military and aerospace.

Confinedly implanted NiFe2O4-rGO: Cluster tailoring and highly tunable electromagnetic properties for selective-frequency microwave absorption

High efficiency and lightweight are key factors for microwave absorption materials. Searching for the above necessary features is still a great challenge. Herein, we deposited small magnetic nickel ferrite nanoparticles on reduced graphene oxide nanosheets uniformly (NiFe2O4/r-GO) using a facile one-pot hydrothermal method with free of chemical agents, and investigated their permittivity, permeability and microwave absorption. Notably, we find an effective strategy for tuning microwave attenuation by the synergistic effect of dielectric and magnetic loss, which originates from inducing multiple relaxations and multiple resonances. The best impedance matching of NiFe2O4/r-GO was sought out. The minimum reflection loss (RL) can reach −42 dB with a broad bandwidth (RL ≤ −10 dB) of 5.3 GHz. Meanwhile, the multiple regions endow the absorbers with selectivity for efficient absorption. Our results demonstrate that the as-prepared NiFe2O4/r-GO is a promising candidate for application in communication devices, high speed processors, information security, electronic countermeasures and electromagnetic interference shielding.

Small magnetic nanoparticles decorating reduced graphene oxides to tune the electromagnetic attenuation capacity

Tailoring rGO-NiFe2O4 hybrids to tune transport of electrons and ions for supercapacitor electrodes

A facile in situ hydrothermal route is adopted for the synthesis of NiFe2O4–reduced graphene oxide (NiFe2O4–rGO) which is verified as a promising high-property anode material for Li-ion batteries. The formation of NiFe2O4 and the reduction of GO occur simultaneously. Ultrafine NiFe2O4 nanocrystals (below 10 nm) disperse uniformly and are immobilized by the reduced graphene oxide. The electrochemical tests show that NiFe2O4–rGO exhibits a high specific capacity of 1129 mA h g−1 at 0.2 A g−1 after ∼300 discharge–charge cycles. The excellent electrochemical properties are mainly ascribed to the introduction of the graphene matrix which offers two-dimensional conductive networks for fast electron transfer and buffers the stress from volume expansion during charge–discharge cycles. Moreover, the NiFe2O4 nanocrystals as the spacers inhibit the aggregation of rGO and form the stacking pore. More importantly, the well-designed heterostructures and the synergistic effects between NiFe2O4 and rGO can enhance the transport of Li+ and electrons and improve the structural stability of the anode, thereby enhancing the electrochemical properties. Our work not only provides an attractive strategy for the design of a hierarchical composite, but also offers a strategy for a promising anode material.

Yan-Lan Zhang

Papers

Graphene nanohybrids: excellent electromagnetic properties for the absorbing and shielding of electromagnetic waves

Confinedly implanted NiFe2O4-rGO: Cluster tailoring and highly tunable electromagnetic properties for selective-frequency microwave absorption

Small magnetic nanoparticles decorating reduced graphene oxides to tune the electromagnetic attenuation capacity

Tailoring rGO-NiFe2O4 hybrids to tune transport of electrons and ions for supercapacitor electrodes

Rational design of NiFe2O4–rGO by tuning the compositional chemistry and its enhanced performance for a Li-ion battery anode