MoS2 wrapped MOF-derived N-doped carbon nanocomposite with wideband electromagnetic wave absorption

Single-atom catalysts (SACs) include a promising family of electrocatalysts with unique geometric structures. Beyond conventional ones with fully isolated metal sites, an emerging class of catalysts with the adjacent metal single atoms exhibiting intersite metal-metal interactions appear in recent years and can be denoted as correlated SACs (C-SACs). This type of catalysts provides more opportunities to achieve substantial structural modification and performance enhancement toward a wider range of electrocatalytic applications. On the basis of a clear identification of metal-metal interactions, this review critically examines the recent research progress in C-SACs. It shows that the control of metal-metal interactions enables regulation of atomic structure, local coordination, and electronic properties of metal single atoms, which facilitate the modulation of electrocatalytic behavior of C-SACs. Last, we outline directions for future work in the design and development of C-SACs, which is indispensable for creating high-performing new SAC architectures.

Metal-metal interactions in correlated single-atom catalysts

Traditional ceramic materials are generally brittle and not flexible with high production costs, which seriously hinders their practical applications. Multifunctional nanofiber ceramic aerogels are highly desirable for applications in extreme environments, however, the integration of multiple functions in their preparation is extremely challenging. To tackle these challenges, we fabricated a multifunctional SiC@SiO2 nanofiber aerogel (SiC@SiO2 NFA) with a three-dimensional (3D) porous cross-linked structure through a simple chemical vapor deposition method and subsequent heat-treatment process. The as-prepared SiC@SiO2 NFA exhibits an ultralow density (~ 11 mg cm- 3), ultra-elastic, fatigue-resistant and refractory performance, high temperature thermal stability, thermal insulation properties, and significant strain-dependent piezoresistive sensing behavior. Furthermore, the SiC@SiO2 NFA shows a superior electromagnetic wave absorption performance with a minimum refection loss (RLmin) value of - 50.36 dB and a maximum effective absorption bandwidth (EABmax) of 8.6 GHz. The successful preparation of this multifunctional aerogel material provides a promising prospect for the design and fabrication of the cutting-edge ceramic materials. 

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Multifunctional SiC@SiO2 Nanofiber Aerogel with Ultrabroadband Electromagnetic Wave Absorption

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Heteroatoms-doped carbon nanocages with enhanced dipolar and defective polarization toward light-weight microwave absorbers

The oxygen evolution reaction (OER) acts as the bottleneck of some crucial energy conversion and storage technologies involving water electrolysis, CO2 electrolysis, and metal‐air batteries, among others. The challenging sluggish reaction kinetics of the OER can be overcome via developing highly efficient electrocatalysts, which experience a dynamic structural evolution process during the reaction. However, the reaction mechanism of the structural transformation of electrocatalysts during the OER and the structure‐activity correlation in understanding the real active sites remain elusive. Fortunately, operando characterizations offer a platform to study the structural evolution processes and the reaction mechanisms of OER electrocatalysts. In this review, using several in situ/operando techniques some recent advances are elaborated with emphases on tracking the structural evolution processes of electrocatalysts, recording the reaction intermediates during electrocatalysis, and building a link between the structure and activity/stability of electrocatalysts. Moreover, theoretical considerations are also discussed to assist operando characterization understanding. Finally, some perspectives are provided which are expected to be helpful to tackle the current challenges in operando monitoring and unraveling the reaction mechanisms of OER electrocatalysts.

Operando Monitoring and Deciphering the Structural Evolution in Oxygen Evolution Electrocatalysis

Improving the atom utilization of metals and clarifying the M-M' interaction is both greatly significant in assembling high-performance ultra-light electromagnetic wave-absorbing materials. Herein, a high-temperature explosion strategy has been successfully applied to assemble the hierarchical porous carbon sponge with Co-Fe decoration via the pyrolysis of the energetic metal organic framework. The as-constructed hybrid displays a superior reflection loss (RL) value of - 57.7 dB and a specific RL value of - 192 dB mg-1 mm-1 at 12.08 GHz with a layer thickness of 2.0 mm (loading of 15 wt%). The off-axis electron hologram characterizes the highly distributed numerous polarized nanodomain variable capacitors, demonstrating the dipole and interfacial polarization along the edges of the nanopores. More importantly, the X-ray absorption spectroscopy analysis verifies the mutual interaction between the metal cluster and carbon matrix and the electronic coupling responsible for the greatly improved electromagnetic wave absorption. 

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Ultrahigh Density of Atomic CoFe-Electron Synergy in Noncontinuous Carbon Matrix for Highly Efficient Magnetic Wave Adsorption

Single-atom catalysts (SACs) are being pursued as economical electrocatalysts. However, their low active-site loading, poor interactions, and unclear catalytic mechanism call for significant advances. Herein, atomically dispersed Ni/Co dual sites anchored on nitrogen-doped carbon (a-NiCo/NC) hollow prisms are rationally designed and synthesized. Benefiting from the atomically dispersed dual-metal sites and their synergistic interactions, the obtained a-NiCo/NC sample exhibits superior electrocatalytic activity and kinetics towards the oxygen evolution reaction. Moreover, density functional theory calculations indicate that the strong synergistic interactions from heteronuclear paired Ni/Co dual sites lead to the optimization of the electronic structure and the reduced reaction energy barrier. This work provides a promising strategy for the synthesis of high-efficiency atomically dispersed dual-site SACs in the field of electrochemical energy storage and conversion.

Highly Efficient Electrocatalytic Oxygen Evolution Over Atomically Dispersed Synergistic  Ni/Co Dual Sites.

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Carbon-based composites with hetero-interfaces is a group of promising electromagnetic wave absorbing materials (EWAMs) for its excellent dielectric loss. For developing this kind of EWAM, in situ constructing hetero-interfaces and...

https://pubs.rsc.org/en/content/articlepdf/2022/ta/d1ta09357f

Huabin Zhang

Papers

Operando Monitoring and Deciphering the Structural Evolution in Oxygen Evolution Electrocatalysis

Ultrahigh Density of Atomic CoFe-Electron Synergy in Noncontinuous Carbon Matrix for Highly Efficient Magnetic Wave Adsorption

Highly Efficient Electrocatalytic Oxygen Evolution Over Atomically Dispersed Synergistic Ni/Co Dual Sites.

Ultrahigh Density of Atomic CoFe-Electron Synergy in Noncontinuous Carbon Matrix for Highly Efficient Magnetic Wave Adsorption

Hollow MoC/NC Sphere for Electromagnetic Wave Attenuation: Direct Observation of Interfacial Polarization on Nanoscale Hetero-interfaces