Tunable High-Performance Microwave Absorption and Shielding by Three Constituent Phases Between rGO and Fe3O4@SiO2 Nanochains.

With the aim of achieving high microwave absorption and electromagnetic shielding performance, reduced graphene oxide (rGO) and Fe3O4@SiO2 nanochains are successfully combined at various mass ratios. By selecting the right mass ratio, an rGO/Fe3O4@SiO2 composite with excellent microwave absorption properties is obtained, and, due to the addition of highly conductive rGO, the desired shielding effectiveness is also achieved. The reflection loss (RL) value of the composite can reach -48.34 dB with a mass ratio of 1:1, and the effective bandwidth (<-10 dB) can cover 4.88 GHz at a thickness of 2.0 mm. Moreover, the composite with a mass ratio of 4:1 exhibits outstanding electromagnetic shielding performance, which also broadens its fields of application. This outstanding microwave absorption and electromagnetic shielding performance indicate that the composite can potentially be employed as a multi-functional material.

Ultrafast Carbon Dioxide Sorption Kinetics Using Morphology-Controllable Lithium Zirconate.

It was reported that the main obstacle of Li2ZrO3 as high-temperature CO2 absorbents is the very slow CO2 sorption kinetics, which are ascribed to the gradual formation of compact zirconia and carbonate shells along with inner unreacted lithium zirconate cores; accordingly, the "sticky" Li+ and O2- ions have to travel a long distance through the solid shells by diffusion. We report here that three-dimensional interconnected nanoporous Li2ZrO3 exhibiting ultrafast kinetics is promising for CO2 sorption. Specifically, nanoporous Li2ZrO3 (LZ-NP) exhibited a rapid sorption rate of 10.28 wt %/min with an uptake of 27 wt % of CO2. Typically, the k1 values of LZ-NP (kinetic parameters extracted from sorption kinetics) were nearly 1 order of magnitude higher than the previously reported conventional Li2ZrO3 reaction systems. Its sorption capacity of 25 wt % within ∼4 min is 2 orders of magnitude faster than those obtained using spherical Li2ZrO3 powders. Furthermore, nanoporous Li2ZrO3 exhibited good stability over 60 absorption-desorption cycles, showing its potential for practical CO2 capture applications. CO2 adsorption isotherms for Li2ZrO3 absorbents were successfully modeled using a double-exponential equation at various CO2 partial pressures.

Excellent microwave absorption properties based on a composite of one dimensional Mo2C@C nanorods and a PVDF matrix.

MoO3 nanowires were synthesized by a wet chemical process and then coated by glucose, and finally successfully turned into Mo2C@C nanorods by carbonation reaction. An excellent absorption strength of -39.0 dB and absorption bandwidth of 12.2 GHz in the thickness range of 2.0-5.0 mm were achieved by the Mo2C@C/PVDF with 10% filler content, derived from effective Debye dipolar relaxation processes. It is expected that the composite can be applied as a novel and desirable microwave absorber.

Controllable Synthesis of One-Dimensional MoO3 /MoS2 Hybrid Composites with their Enhanced Efficient Electromagnetic Wave Absorption Properties.

One-dimensional MoO3 /MoS2 hybrid composites were synthesized by hydrothermal synthesis, and flexible MoO3 /MoS2 /PVDF nanocomposites could be prepared in a controlled fashion by combining the MoO3 /MoS2 composites with polyvinylidene fluoride (PVDF) matrix. The MoO3 /MoS2 /PVDF hybrids with a low filler content (20 wt %) exhibited distinct microwave absorption properties in the range of 2-18 GHz. The minimum reflection loss can reach -38.5 dB at 8.7 GHz, and the reflection loss was less than -10 dB in the frequency range from 3.03-11.02 GHz with an absorber thickness of 2.0-5.0 mm. The MoO3 /MoS2 /PVDF nanocomposites exhibited better absorption properties than pure MoO3 and MoS2 . The possible microwave absorption mechanism was also discussed in detail.

Hierarchically Structured Graphene Coupled Microporous Organic Polymers for Superior CO2 Capture.

Hierarchically porous materials containing interconnected macro-/meso-/micropores are promising candidates for energy storage, catalysis, and gas separation. Here, we present an effective approach for synthesizing three-dimensional (3D) sulfonated graphene coupled microporous organic polymers (SG-MOPs). The resulting SG-MOPs possess uniform macropores with an average size of ca. 350 nm, abundant mesopores, and micropores with an average size of ca. 0.6 nm. The SG-supported adsorbents exhibit a high nitrogen content (more than 38.1 wt %), high adsorption capacity (up to 3.37 mmol CO2 g-1), high CO2/N2 selectivity from 42 to 51, moderate heat of adsorption, as well as good stability because of the hierarchical porous structure and excellent thermal conductivity of the SG scaffold. Thus, these nitrogen-enriched adsorbents allow the overall CO2 capture process to be promising and sustainable.

Amine-tethered adsorbents based on three-dimensional macroporous silica for CO(2) capture from simulated flue gas and air.

New covalently tethered CO2 adsorbents are synthesized through the in situ polymerization of N-carboxyanhydride (NCA) of l-alanine from amine-functionalized three-dimensional (3D) interconnected macroporous silica (MPS). The interconnected macropores provide low-resistant pathways for the diffusion of CO2 molecules, while the abundant mesopores ensure the high pore volume. The adsorbents exhibit high molecular weight (of up to 13058 Da), high amine loading (more than 10.98 mmol N g(-1)), fast CO2 capture kinetics (t1/2 < 1 min), high adsorption capacity (of up to 3.86 mmol CO2 g(-1) in simulated flue gas and 2.65 mmol CO2 g(-1) in simulated ambient air under 1 atm of dry CO2), as well as good stability over 120 adsorption-desorption cycles, which allows the overall CO2 capture process to be promising and sustainable.