Anchoring Polar Organic Molecules in Defective Ammonium Vanadate for High-Performance Flexible Aqueous Zinc-Ion Battery.

Ammonium vanadate (NVO) often has unsatisfactory electrochemical performance due to the irreversible removal of NH4 + during the reaction. Herein, layered DMF-NVO nanoflake arrays (NFAs) grown on highly conductive carbon cloth (CC) are employed as the binder-free cathode (DMF-NVO NFAs/CC), which produces an enlarged interlayer spacing of 12.6 Å (against 9.5 Å for NH4 V4 O10 ) by effective N, N-dimethylformamide (DMF) intercalation. Furthermore, the strong attraction of highly polar carbonyl and ammonium ions in DMF can stabilize the lattice structure, and low-polar alkyl groups can interact with the weak electrostatic generated by Zn2+ , which allows Zn2+ to be freely intercalated. The DMF-NVO NFAs/CC//Zn battery exhibits an impressive high capacity of 536 mAh g-1 at 0.5 A g-1 , excellent rate capability, and cycling performance. The results of density functional theory simulation demonstrate that the intercalation of DMF can significantly reduce the band gap and the diffusion barrier of Zn2+ , and can also accommodate more Zn2+ . The assembled flexible aqueous rechargeable zinc ion batteries (FARZIBs) exhibit outstanding energy density and power density, up to 436 Wh kg-1 at 400 W kg-1 , and still remains 180 Wh kg-1 at 4000 W kg-1 . This work can provide a reference for the design of cathode materials for high-performance FARZIBs.

Synthesis of dendritic cobalt with flower-like structure by a facile wet chemistry method as an excellent electromagnetic wave absorber.

In this study, a three-dimensional (3D) floral dendritic cobalt (FDC) consisting of layered flakes was effectively synthesized using a facile wet chemistry method. The impact of the molar amount of NaOH on the microscopic morphology, magnetic characteristics, and electromagnetic wave (EMW) absorption properties of the FDC magnetic materials was comprehensively investigated. The results revealed that the prepared FDC features primary, secondary, and multi-level branches, with the majority of secondary branches being parallel to one another. The dendrites grew closely towards the flower's center at one end, while the tips extend in various directions, forming a dendritic flower cluster. The optimal reflection loss (RL) of S3 at 9.3 GHz was -56.34 dB with a thickness of 1.89 mm, and the maximum effective absorption bandwidth (EAB, RL < -10 dB) reached 6.0 GHz (12.0-18.0 GHz) at a thickness of 1.30 mm. Consequently, the FDC magnetic materials produced in this study presented a method for fabricating high-performance electromagnetic wave absorption (EMWA) materials.

Synthesis of NiCo-BNSA/RGO/MDCF with three-dimensional porous network structure as an excellent microwave absorber.

Melamine-derived carbon foam (MDCF) and nickel-cobalt bimetallic nanosheet arrays (NiCo-BNSA) possess unique porous structures and excellent microwave absorption (MA) properties, making them potentially useful in MA applications. In this investigation, we fabricated NiCo-BNSA/reduced graphene oxide/MDCF (NiCo-BNSA/RGO/MDCF) composites utilizing a two-stage synthesis protocol. This process incorporated melamine foam (MF) pretreatment, carbonization, and a subsequent in-situ growth stage, resulting in the creation of a three-dimensional porous network structure. By adjusting the RGO volume, we were able to manipulate the structure and composition of the NiCo-BNSA/RGO/MDCF composites, leading to an enhancement in their MA performance. It was also observed that the NiCo-BNSA was evenly distributed on the surface of both the RGO and MDCF. The composites exhibited an optimal reflection loss (RLmin) of -67.8 dB at a thickness of 2.50 mm, and by varying their thickness, the effective absorption bandwidth (EAB, RL ≤ -10 dB) extended to 9.80 GHz, encompassing the entire C and X bands. This study presents a novel approach for fabricating lightweight and efficient carbon-based MA composites.

Lightweight and efficient luffa sponge carbon/Co composites with adjustable electromagnetic wave absorption properties.

Biomass material has gained significant popularity due to its potential to meet the requirements of green and sustainable development in modern times. It is widely used in various fields, especially for absorbing electromagnetic waves (EMW). In this study, we used luffa sponge carbon (CLS) as a lightweight and porous carbon source. Through a static reaction and heat treatment process, we successfully loaded coral sheet cobalt onto the surface of CLS to create lightweight and efficient luffa sponge carbon/cobalt (CLS/Co) composites for EMW absorption. We controlled the microstructure and electromagnetic properties of the CLS/Co composites by adjusting the pyrolysis temperature. At 700 °C, the CLS/Co composites showed a minimum reflection loss (RLmin) of -60.81 dB and an effective absorption bandwidth (EAB) of 5.56 GHz at a very thin thickness of 1.68 mm. Moreover, at a pyrolysis temperature of 800 °C, the absorption strength of the CLS/Co composites reached -50 dB at various thicknesses.

In Situ Construction of Heterostructured Co3O4/CoP Nanoflake Arrays on Carbon Cloth as Binder-Free Anode for High-Performance Lithium-Ion Batteries.

Cobalt oxide (Co3O4) is regarded as the anode material for lithium-ion batteries (LIBs) with great research value owing to its environmental friendliness and exceptional theoretical capacity. However, the low intrinsic conductivity, poor electrochemical kinetics, and unsatisfactory cycling performance severely limit its practical applications in LIBs. The construction of a self-standing electrode with heterostructure by introducing a highly conductive cobalt-based compound is an effective strategy to solve the above issues. Herein, Co3O4/CoP nanoflake arrays (NFAs) with heterostructure are constructed skillfully directly grown on carbon cloth (CC) by in situ phosphorization as an anode for LIBs. Density functional theory simulation results demonstrate that the construction of heterostructure greatly increases the electronic conductivity and Li ion adsorption energy. The Co3O4/CoP NFAs/CC exhibited an extraordinary capacity (1490.7 mA h g-l at 0.1 A g-l) and excellent performance at high current density (769.1 mA h g-l at 2.0 A g-l), as well as remarkable cyclic stability (451.3 mA h g-l after 300 cycles with a 58.7% capacity retention rate). The reasonable construction of heterostructure can promote the interfacial ion transport, significantly enhance the adsorption energy of lithium ions, improve the conductivity of Co3O4 electrode material, promote the partial charge transfer throughout the charge and discharge cycles, and enhance the overall electrochemical performance of the material.

Carbon cloth based flexible electromagnetic wave absorbing materials loaded with Co3O4 array and tunable electromagnetic wave absorption performance.

The demand for flexible electromagnetic wave (EMW) absorbing materials has increased, highlighting the importance of designing efficient and adaptable EMW absorbing materials. In this study, flexible Co3O4/carbon cloth (Co3O4/CC) composites with high EMW absorption properties were prepared via a static growth method and annealing process. The composites exhibited remarkable properties, with the minimum reflection loss (RLmin) and maximum effective absorption bandwidth (EAB, RL ≤ -10 dB) of -54.43 dB and 4.54 GHz, respectively. The flexible carbon cloth (CC) substrates exhibited outstanding dielectric loss due to their conductive networks. Moreover, the uniformly and tightly organized Co3O4 arrays on the flexible CC substrate played a crucial role in fine-tuning the impedance matching and facilitating abundant multiple scattering and interface polarization. This study proposes a promising approach to preparing flexible Co3O4/CC composites with a significant reference value for the field of flexible EMW.

In-situ hydrothermal synthesis of NiCo alloy particles@hydrophilic carbon cloth to construct corncob-like heterostructure for high-performance electromagnetic wave absorbers.

NiCo alloy particles (NiCo-APs)@hydrophilic carbon cloth (HCC) composites were successfully prepared by uniformly decorating magnetic NiCo-APs on the surface of three-dimensional HCC by employing an in-situ hydrothermal method. The NiCo-APs@HCC composites exhibited a unique corncob-like network structure that helped improve the electromagnetic wave (EMW) absorption performance of composites. The EMW absorption properties of the composites could be controlled by altering the Ni/Co molar ratio. The optimal minimum reflection loss (RLmin) of -41.80 dB was achieved with the NiCo-APs@HCC composite thickness of 2.29 mm. The effective absorption bandwidth (EAB) reached the maximum of 5.8 GHz, spanning nearly the entire Ku band. In addition, the improved EMW absorption performance was further promoted by favorable impedance matching, strong conduction loss, magnetic loss, dipole polarization, interface polarization, multiple reflections, and scattering. A novel strategy for designing magnetic metal/carbon matrix composites with excellent EMW absorption performance is reported in this study.

Constructing interpenetrating structured NiCo2O4/HCNT composites with heterogeneous interfaces as low-thickness microwave absorber.

Low matching thickness, broad effective absorption bandwidth (EAB, RL < -10 dB) and excellent reflection loss (RL) are desirable properties for the advanced microwave absorption materials (MAMs). We synthesized novel interpenetrating structured rod-like nickel cobaltite (NiCo2O4)/helical carbon nanotubes (HCNT) composites using the facile hydrothermal technique and heat-treatment process. Owing to the optimum structural design and electromagnetic parameter regulation, the NiCo2O4/HCNT composites displayed outstanding microwave absorption (MA) across regions of low thickness. When the thickness was only 1.35 mm, the optimized RL and EAB reached -55.9 dB and 4.8 GHz (13.2-18.0 GHz), respectively. Furthermore, the EAB was 10 GHz as the corresponding thickness was regulated with 1.35-2.10 mm, covering both X and the Ku bands. Multiple reflection and scattering, natural resonance, eddy current loss, strong conduction loss, interface polarization, cross-poalarization, and dipolar polarization can be considered to improve MA. Our study proposes a simple approach of synthesizing low-thickness MAMs based on NiCo2O4 and HCNT.

In-situ synthesis of graphite carbon nitride nanotubes/Cobalt@Carbon with castor-fruit-like structure as high-efficiency electromagnetic wave absorbers.

The increasingly electromagnetic wave (EMW) pollution has rendered the study and development of new, high-efficiency EMW absorbers a sought-after topic. In this study, graphite carbon nitride nanotubes/cobalt@carbon (GCNNs/Co@C) composites were fabricated using an in-situ synthesis method, which included facile grinding and carbonization pyrolysis. The synthesized GCNNs/Co@C composites exhibited a unique castor-fruit-like structure, that is, GCNNs formed an entwined three-dimensional (3D) network structure on the surface of cobalt@carbon (Co@C), which improved the EMW absorption properties of composites. The obtained GCNNs/Co@C composites exhibited excellent EMW absorption performance. For the fabricated GCNNs/Co@C composites, the minimum reflection loss (RLmin) value reached -63.90 dB at a thickness of 1.96 mm, and the effective absorption bandwidth (EAB, RL ≤  -10 dB) achieved 4.44 GHz at an ultra-thin thickness of 1.51 mm. The EAB covered the entire X and Ku bands (6.96-18.00 GHz) through thickness adjustment from 1.51 to 2.50 mm. Underlying EMW absorption mechanisms were briefly discussed. This study presents a novel design method to prepare light-weight and highly-efficient EMW absorbing absorbers.