To develop high-performance microwave absorption materials with the features of lightweight, thin thickness, broad bandwidth, and strong absorption, an ultralight Ni3S2@N, S-codoped graphene aerogel with a density of 13.5 mg/cm3has been fabricated by the use of metal-organic frameworks (MOFs) to directly initiate the gelation of graphene oxide strategy. In such a strategy, dual-functional 1D Ni-MOF nanorods not only act as the gelation agent but also afford the doping elements (N and S) originated from the organic species and the precursor for metal sulfide. Due to the synergistic effects of good impedance matching and multiple losses, the optimal reflection loss (RL) of as-prepared Ni3S2@N, S-codoped graphene aerogel reaches −46.9 dB at 17.1 GHz with only 2.0 mm and ultralow filling content (1.75 wt%). The maximum effective absorption bandwidth (EAB) reaches 6.3 GHz (11.7–18.0 GHz) at 2.38 mm, covering the whole Ku band. Moreover, the value of EAB with the RL less than −30 dB can be tuned to 12.2 GHz (5.8–18 GHz) at the absorber thickness ranging from 1.9 to 5.0 mm. This work provides insight for rational design and fabrication of multicomponent-containing graphene aerogels, showing the potential application in lightweight and high-performance microwave absorption.
Transition metal sulphides derived from metal–organic frameworks (MOFs) have gained increasing attention as promising electrode materials for energy storage, owing to their elevated theoretical capacitance and exceptional electrochemical features. Herein, a simple dual organic ligand strategy and controllable pyrolysis treatment were used to prepare porous micro-rods Co 9 S 8 /Ni 3 S 2 /NC-T (T denotes for temperature) composite materials. Their structure and composition can be precisely controlled by adjusting the pyrolysis temperature. Co 9 S 8 /Ni 3 S 2 /NC-T composite materials possess rich pore structures, unique three-dimensional carbon conductive networks and synergistic effects of Co 9 S 8 and Ni 3 S 2 . Experimental results of cyclic voltammetry revealed that the bimetal sulphides in Co 9 S 8 /Ni 3 S 2 /NC-T can provide substantial redox pseudocapacitance for electrochemical reactions. Electrochemical tests indicated that the optimal carbonization temperature was 700°C, and the Co 9 S 8 /Ni 3 S 2 /NC-700 electrode material has the highest specific capacity of 2288 F g −1 at a current density of 1 A g −1 and an excellent rate capability with retention of about 61.2% at a current density of 10 A g −1 . This study provides methodological guidance for the rational composition control and unique structure of MOF-derived materials for supercapacitors. Graphical
Rational construction of self-supporting electrodes has been extensively investigated in energy conversion and storage. In this work, hierarchical N-doped carbon-encapsulated Ni3S2 grown on a 3D porous Ni foam (H-Ni3S2@NC/NF) was controllably synthesized by a one-pot self-templated solvothermal method. Herein, we highlight the self-templated growth of multilayered Ni3S2 with N-doped carbon intercalation at a certain temperature. The unique H-Ni3S2@NC/NF shows enhanced active sites and a modulated electronic structure, which facilitates mass/electron transport. Thereby, the H-Ni3S2@NC outperforms a lower overpotential of 238 mV at 10 mA cm−2 and a low Tafel slope of 62 mV dec−1 than that of binary and ternary metal sulfides, suggesting an excellent mono-metal sulfide as a self-supporting electrode for oxygen evolution reaction.
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