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In alkaline seawater electrolysis, the oxygen evolution reaction (OER) is greatly suppressed by the occurrence of electrode corrosion due to the formation of hypochlorite. Herein, a catalyst consisting of MoC nanowires modified with NiFe alloy nanoparticles (NiFe/MoC) on nickel foam (NF) is prepared. The optimized catalyst can deliver a large current density of 500 mA cm−2 at a very low overpotential of 366 mV in alkaline seawater, respectively, outperforming commercial IrO2. Remarkably, an electrolyzer assembled with NiFe/MoC/NF as the anode and NiMoN/NF as the cathode only requires 1.77 V to drive a current density of 500 mA cm−2 for alkaline seawater electrolysis, as well as excellent stability. Theory calculation indicates that the initial activity of NiFe/MoC is attributed to increased electrical conductivity and decreased energy barrier for OER due to the introduction of Fe. We find that the change of the catalyst in the composition occurred after the stability test; however, the reconstructed catalyst has an energy barrier close to that of the pristine one, which is responsible for its excellent long‐term stability. Our findings provide an efficient way to construct high‐performance OER catalysts for alkaline seawater splitting. [ABSTRACT FROM AUTHOR]

The achievement of bifunctional metal‐organic frameworks (MOFs) remains a huge challenge due to their lack of dual active sites. Herein, dual sites in the Co‐catecholate (Co‐CAT) are created through Ru, Ir, or Rh doping for overall water splitting. Among them, RuCo‐CAT exhibits excellent bifunctional activities, outperforming benchmarked Pt/C for the hydrogen evolution reaction (HER) and RuO2 for the oxygen evolution reaction (OER). The theoretical calculations demonstrate that the doped Ru atoms with optimal absorption energy for the hydrogen intermediate and the Co centers with a reduced energy barrier for the rate‐determining step are the active sites for HER and OER, respectively. Furthermore, the incorporation of Ru atoms can improve the electrical conductivity and capacity of water adsorption of Co‐CAT greatly, synergistically improving the bifunctional activity. This strategy for engineering dual active sites offers novel insights into designing bifunctional MOFs for overall water splitting. [ABSTRACT FROM AUTHOR]

Nanocarbons with single‐metal atoms (M‐SAs) have displayed considerable potential in various fields of application due to high free energy of M‐SAs and strong metal‐support interaction. However, the uniform dispersion of M‐SAs within the whole carbon matrix still remains a great challenge. Herein, Ni‐SAs are uniformly dispersed within hierarchically porous carbon nanoflowers (Ni‐SA/HPCF) via a spatial confinement of Ni ions within the periodic pores in metal‐organic frameworks (MOFs) with a subsequent carbonization process. The Ni‐SA/HPCF with abundant mesopores and an ultrahigh surface area (1137.2 m2 g−1) exhibits unexpected electromagnetic wave (EMW) absorption property with a minimal reflection loss of –53.2 dB and an effective absorption bandwidth of 5.0 GHz, while the filler ratio in the matrix is merely 10 wt.%. Density functional theory calculations and experimental results reveal that the uniformly dispersed Ni‐SAs break local symmetry of the electronic structure and increase electrical conductivity of host carbon matrix, thereby enhancing the EMW absorption properties. In addition, the unique 3D hierarchical porous morphology boosts the impedance matching property, which synergistically improves the EMW absorption performance of the Ni‐SA/HPCF. This study provides an efficient approach to uniformly disperse M‐SAs within hierarchically porous nanocarbons for EMW absorption and other potential applications. [ABSTRACT FROM AUTHOR]

With the current rapid growth of commercial applications for flexible and wearable optoelectronic devices, flexible power sources are very much in demand. Herein, a facile strategy to grow cobalt nanoparticles encapsulated in nitrogen‐doped carbon nanotube arrays on flexible carbon fiber cloth as self‐supported electrodes for high‐performance flexible zinc–air batteries is developed. Benefiting from high electrical conductivity and multiple active sites as well as free polymer binder, the self‐supported electrode exhibits excellent electrocatalytic activity. The maximum power density of a zinc–air battery using the self‐supported electrode as air cathode is higher than that of the zinc–air battery with Pt/C+IrO2 as air electrode. Furthermore, the zinc–air battery can be stably operated under external stress without obvious loss of the electrochemical performance. This work opens up a new pathway for the rational design of flexible electrodes for high‐performance flexible power sources. [ABSTRACT FROM AUTHOR]

• Sufficient internal cavities of nanosphere improves impedance matching properties. • The multi-component heterostructure of Fe 3 O 4 /FeS x enhances interfacial polarization. • Fe 3 O 4 /FeS x nanospheres have optimal structural integrity and crystallinity at 400°C. • Hollow Fe 3 O 4 /FeS x nanospheres and graphene aerogel improve lightweight properties. • The RL and EAB of the synthesized materials are -43.03 dB and 4.24 GHz, respectively. The fabrication of materials featuring hollow structures or multi-component heterostructures effectively enhance the performance of electric/magnetic loss and improve the impedance matching properties of absorbers. In this work, by precisely controlling the sulfidation temperature at 400°C and incorporating rGO, we successfully obtained Fe 3 O 4 /FeS x -rGO aerogel materials with exceptional structural integrity and crystallinity. The electromagnetic parameter analysis and calculation confirm the enhancement of impedance matching, interface polarization, electrical conductivity, and dielectric loss capability of the hollow structure and multi-interface heterostructure; while computer simulation technology results verify the effective attenuation capability of the absorber for electromagnetic energy under practical application conditions. As a result, the reflection loss of Fe 3 O 4 /FeS x -rGO reach −43.03 dB at a thickness of only 2.0 mm and the effective absorption bandwidths is 4.24 GHz at a thickness of 1.6 mm. This multifactorial synergistic enhancement mechanism provides a new idea for the design and preparation of high-performance electromagnetic wave absorbing materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Rational design of the morphology and structure is important for the functional materials to improve their physicochemical properties. Herein, we design hierarchically three-dimensional (3D) structures assembled with yolk-shelled spheres-supported nitrogen-doped CNTs (NCNTs) using Ni(OH) 2 @SiO 2 core-shelled spheres as precursors for electromagnetic wave absorption. In the 3D structures, the yolk materials are SiO 2 spheres, while the shell materials are N-doped carbon layers containing Ni, Si and O elements. Importantly, The NCNT arrays with encapsulated Ni NPs are branched out from the yolk-shelled spheres. The hierarchical structures feature the merits of both yolk-shelled and 3D structures. Furthermore, the SiO 2 sphere in the 3D structure can tune the electrical conductivity, affording our hierarchically 3D structure better impedance matching characteristic for electromagnetic wave absorption. As a result, the reflection loss and effective absorption bandwidth of our optimal 3D structure can reach −59.90 dB and 4.24 GHz, respectively, while the thickness of the absorbing film is only 1.4 mm, superior to most of reported carbon-based absorbers. The present method for the regulation of the structure and morphology provides an efficient way to construction of high-performance electromagnetic wave absorbers. [Display omitted] • Yolk-shelled sphere-supported nitrogen-doped carbon nanotubes were fabricated. • The hierarchical structures have the merits of both yolk-shelled and 3D structures. • SiO 2 sphere in the 3D structure can optimize impedance matching characteristic. • The absorption bandwidth of the sample is 4.24 GHz with a thickness of 1.4 mm. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have important application in electromagnetic wave absorption due to their unique tubular structure, lightweight feature and high electrical conductivity. However, sole CNTs suffer from bad impedance matching characteristic, leading to unsatisfactory absorption performance. Herein we propose a universal SiO 2 -assisted strategy to fabricate Ni nanoparticle-encapsulated nitrogen-doped CNTs on the SiO 2 spheres (Ni@NCNT@SiO 2). Due to the spatial separating effect, the formation of large metal aggregates and large-sized NCNTs in the products are avoided effectively. In the meanwhile, the ideal impedance matching characteristic is also achieved due to the introduction of the non-conductive SiO 2 spheres. As a result, even with a low matching thickness (1.3–2.0 mm), the reflection loss values of Ni@NCNT@SiO 2 reaches −30 dB. Furthermore, the proposed method can be also used to fabricate Fe 3 C/Fe@NCNT@SiO 2 and Co@NCNT@SiO 2 with satisfactory absorption properties, demonstrating its universality for synthesis of high-performance absorbers based on CNTs. Image 1 • A universal SiO 2 -assisted method is proposed to fabricate magnetic NP-embedded NCNTs. • The size and impedance matching characteristic of the NCNTs are tailored effectively. • The absorption bandwidth of the NCNTs is 4.14 GHz with a thickness of merely 1.5 mm. • The proposed method can be extended to design other high-performance absorbers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flexible and waterproof NCNT arrays on carbon fiber (NCNT@CF) were fabricated. • NCNT@CF exhibited excellent EMW absorption performances. • The R L,min value and EAB 10 of NCNT@CF are − 57.8 dB and 4.5 GHz, respectively. • RCS values of the materials were simulated under real far field conditions. • NCNT@CF had flexible, waterproof, and electric-thermal conversion functions. It is highly desirable, but challenging to develop multi-functional electromagnetic wave (EMW) absorbing material for practical applications in some special environments. Herein, we successfully fabricated cobalt-nanoparticle-embedded N-doped carbon nanotube arrays on the carbonized cotton fiber cloth as multifunctional material with an excellent EMW absorption, flexibility, hydrophobicity, and electric-thermal performance. The excellent multifunction benefits from high conductivity, large specific surface area, abundant N dopants, and three-dimensional open porous features. Minimal reflection loss and efficient absorption bandwidth of the optimized material as EMW absorbers can reach − 57.8 dB and 4.5 GHz, respectively, which are better than most reported carbon-based absorbers. Meanwhile, theoretical simulations of the radar cross-sectional (RCS) further confirm that the multifunctional material has excellent EMW attenuation performance and potential in practical application. Moreover, the materials possess strong hydrophobicity and high electrical conductivity, endowing them with other attractive functions of self-cleaning and good electric thermal performance, which expand the potential applications range of EMW absorption materials. Our present method can be extended to design next-generation EMW absorbing materials with multifunctionalities for practical applications in harsh environments. [ABSTRACT FROM AUTHOR]