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Carbon-based magnetic composites with enhanced electromagnetic (EM) wave absorption ability have received intensive attention. Herein, a composite of N-graphene and small size magnetic Co nanoparticles (NPs) with advantages of excellent dielectric ability was synthesized through an in situ grown method. Under optimized conditions, Co NPs decorated on NGN (Co/NGN-2) have the best EM wave absorption performance, of which a minimum reflection loss of − 45.8 dB can be achieved at 13.48 GHz with a thin coating of 2 mm at 15 wt% filler loading in paraffin wax. The effective absorption bandwidth is about 4.6 GHz in Ku-band (12.4–18 GHz). Importantly, the effective absorption bandwidth can be extended by changing the thickness of the absorber. In fact, the coupling of NGN with Co NPs can form an effective impedance match, and thus the small size Co NPs with low density and good performance decorated on NGN material make the present method promising for EM applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The morphology design strategies of Co-related compounds were systematically summarized. • The catalytic mechanism of Co-related oxygen electrocatalysts was mainly explored. • The future research directions of Co-related catalysts applied in Zn-air batteries were prospected. Zinc-air batteries (ZABs) have been widely investigated in fields such as energy, materials, and devices due to their green and efficient characteristics. Nonetheless, the electrochemical performance of ZABs is limited by the ability of the cathode to catalyze oxygen reactions. Pt-based and Ir or Ru-based precious metals have been successfully used as catalysts in the market. Due to the scarce resources and high costs of these precious metals, non-precious metal catalysts have been able to conduct research. Among them, cobalt-related transition metal catalysts are considered one of the most promising candidates due to their low cost and high activity. However, poor conductivity and cyclic stability limit its commercial application. Nano design is extremely important in improving catalytic performance, especially one-dimensional (1D) morphology control has been confirmed to be an effective modification method for improving electrochemical performance. In this review, the principles for designing 1D cobalt-related oxygen electrocatalysts toward high-performance ZABs, such as Co-immobilized carbon composites, cobalt oxides, cobalt sulfides, and cobalt phosphides are reviewed. Next, the strategies aiming at improving the electrocatalytic activity and stability are summarized. At last, the challenges and perspectives of cobalt-related oxygen electrocatalysts for ZABs are discussed. This review can offer insights into the targeted optimization of 1D cobalt-related oxygen electrocatalysts, which can be expected to shed light on the future development of high-performance ZABs. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries appear to be one of the most promising energy-storage devices owing to the unparalleled theoretical specific energy, relatively inexpensive price and abundant resources. Despite these attractive features, the practical performances of sulfur cathode still remain a lot of challenges, such as the electrical insulating nature of S and Li 2 S, huge volume change during cycling, notorious shuttle effect of lithium polysulfide intermediates (LiPSs), sluggish redox kinetics and construction of thick electrodes with high sulfur loading. Here, CoFe 2 O 4 nanoparticles anchored on the carbon nanotube (CNT) paper is proposed as free-standing sulfur host to address the issues. The cross-linking CNT network can serve as conductive matrix and accommodate volume change upon cycling simultaneously. Meanwhile, the CoFe 2 O 4 nanoparticles are capable of effectively anchoring LiPSs to suppress the shuttle effect and accelerating LiPSs conversion to boost redox kinetics. Moreover, the free-standing paper electrode without any binder is conducive to constructing stable cathode with high sulfur loading. In consequence, the well-designed S/CoFe 2 O 4 /CNT paper cathodes deliver impressive electrochemical performance, demonstrating an initial discharge capacity of 755.3 mAh g−1 and remaining a high reversible capacity of 642.6 mAh g−1 after 400 cycles at 2 C with an inconspicuous decay of 0.04% per cycle. The bimetallic oxide CoFe 2 O 4 nanoparticles anchored on the carbon nanotube paper is proposed as free-standing sulfur host with enhanced polysulfide trapping and catalytic effects for advanced Li-S batteries. [Display omitted] • Binder-free host realizes high sulfur loading and energy density for Li-S battery. • CoFe 2 O 4 /CNT paper inhibits the polysulfide shuttling via strong chemical interaction. • CNT-anchored CoFe 2 O 4 catalytically promotes the polysulfide conversion kinetics. • The Li-S battery with S/CoFe 2 O 4 /CNT cathode exhibits enhanced capacity and stability. [ABSTRACT FROM AUTHOR]