Facile morphology-controlled synthesis of nickel-coated graphite core-shell particles for excellent conducting performance of polymer-matrix composites and enhanced catalytic reduction of 4-nitrophenol

Low density magnetic silicate-nickel alloy composite hollow structures: seed induced direct assembly fabrication and catalytic properties

An efficient seed induced direct assembly route is designed for the controlled synthesis of hollow microsphere supported catalysts (HMSCs) with nickel alloy as the active material. The inherent magnetic response of nickel alloy endows HMSCs magnetic separability, and the hollow interior of the support opens a new avenue for self-floating separation. It is found that the introduction of P and Co contributes largely to the improvement of the catalytic performance of the products, which may attributed to synergistic effects and electron transfer. Moreover, the loading amounts of alloy nanoparticles can be easily tailored through properly monitoring the reaction conditions. With the optimized loading of 2.68 wt%, the k_N of HMSC–NiCoP-2.68 wt% reaches 14.0 s⁻¹ g⁻¹ for the catalytic reduction of p-nitrophenol (4-NP), which is higher than commercial 5 wt% Pd/C of 11.6 s⁻¹ g⁻¹ under the same conditions. This work provides additional insights into preparation and property control of an easily separable supported non-noble metal catalyst, which holds potential to be extended to the preparation and property control of other metal nanocatalysts on various supports.

Synthesized HMSC–NiCoP-2.68 wt% catalyst exhibits excellent catalytic reduction activity of 4-NP, which can be separated by self-floating and external magnetic field.

Electroless Plating of Graphene Aerogel Fibers for Electrothermal and Electromagnetic Applications

Graphene aerogel fibers (GAFs) with low density, high specific surface area, and high porosity can be used as the host material to incorporate another component and thus form multifunctional fibers, which have potential applications in wearable devices, thermoregulating apparatus, sensors, and so forth. However, the intrinsically low electric conductivity of GAFs hampers them in the fields of electrothermal heating and electromagnetic interference (EMI) shielding. Herein, we report a new aerogel fiber composed by graphene sheets and nickel nanoparticles with low density (55-192 mg/cm³), high electric conductivity (0.8 × 10³ to 4.5 × 10⁴ S/m), and high specific surface area (49-105 m²/g). The graphene/Ni aerogel fibers (GNAFs) were synthesized initially from reduced graphene oxide hydrogel fibers followed by an electroless plating process. Further investigations have demonstrated that the resulting GNAFs possess excellent electrothermal property, faster electrothermal response, high mechanical and electrical stability as the electric wire, and excellent EMI shielding performance as the composite filler. The saturated temperature of GNAFs can reach 174 °C with an applied voltage of only 5 V, and the heating rate surpasses those of commercial Kanthal and Nichrome wires about 2.1 times and 2.6 times, respectively. The EMI shielding effectiveness of GNAFs is higher than 30 dB at the long bandwidth of 12.5-20 GHz. Specifically, it can shield more than 99.99% of the incident wave at the bandwidth of 15-20 GHz.