CVD synthesis of carbon spheres using NiFe-LDHs as catalytic precursors: structural, electrochemical and magnetoresistive properties

Abstract

The gram-scale synthesis of carbon spheres with a diameter of ca. 740 nm has been achieved by means of a chemical vapour deposition method using NiFe-layered double hydroxides as a solid catalytic precursor. The presence of the catalyst (FeNi 3 ) allows controlling the final size distribution, resulting in a monodisperse sample. Their structural properties exhibited a high degree of graphitization according to their I D /I G ratio. In addition, their morphological features were unveiled by FIB-SEM and HRTEM, showing that they are formed by solid inner cores, and presenting labile chain-like structures due to accretion procedures. The solution and posterior sonication of the samples in toluene gave rise to the well-defined isolated spheres. The textural and electrochemical properties of the spheres have been tested showing non-mesoporous structures with a good behaviour as electrode materials for supercapacitors due to the presence of redox functionalities on their surface. Finally, magneto-transport measurements have been carried out, demonstrating semiconductor behaviour, as well as a positive magnetoresistance effect (ca. 72%) for the lowest studied temperature (2 K).

Alkoxide-intercalated NiFe-layered double hydroxides magnetic nanosheets as efficient water oxidation electrocatalysts

“…[18][19][20][21] The synthesis and exfoliation of pure NiFe-LDHs with high crystallinity and well-defined hexagonal shapes have remained elusive so far. 22,23 Currently, there are two main routes for the synthesis of pure NiFe-LDHs that can be exfoliated into 2D nanosheets, namely the hydrothermal approach using urea as ammonium releasing reagent and triethanolamine as chelating reagent, 23,24 and the use of anthraquinone-2-sulfate that favors the topochemical oxidation of the metals during the layer formation.…”

Facile Synthesis of Mesoporous Carbon Spheres Using 3D Cubic Fe-KIT-6 by CVD Technique for the Application of Active Electrode Materials in Supercapacitors

“…The values were nearly close and slightly higher than that of the pure graphitic carbon (0.335 nm), which indicated that the MCS consists of relatively well-graphitized carbon structure. 23,31…”

Co3O4 nanosheet-built hollow dodecahedrons via a two-step self-templated method and their multifunctional applications

“…It could remain the original structure after thermal treatment and be easily modified by the nanoscale metal nanoparticles (NPs) with a uniform particle size and high dispersion. With these advantages, LDHs are not only widely applied in various fields such as catalysts, supercapacitors, but also used as supports or precursors to further fabricate the functional materials [22][23][24]. For example, Gao et al [25] reported that Mg-Al-CO 3 LDH-derived mixed metal oxides were applied for high-temperature CO 2 capture.…”