Enhanced Protection of Carbon-Encapsulated Magnetic Nickel Nanoparticles through a Sucrose-Based Synthetic Strategy

Abstract

We report an easy synthesis strategy for the incorporation of carbon-coated Ni nanoparticles within the pores of a highly porous carbon matrix. An advantageous feature of this process is that it is able to provide large amounts of magnetic Ni composite by means of an easy-to-follow one-pot reaction. While a typical chemical route based on a conventional pyrolysis procedure gives rise to NPs with Ni@NiO (core@shell structure), the addition of sucrose to the synthesis mixture and its subsequent transformation to carbon endows the Ni-NPs with an effective protection via the formation of a thin carbon layer around the metallic nanoparticles. This protective shell stabilizes the inserted metallic particles by preventing the aerial oxidation of Ni-NPs (i.e., NiO) and their dissolution in an aqueous acid environment. The macroscopic magnetization values of these nanocomposites (up to 6 emu/g) and their superparamagnetic behavior at room temperature allow them to be easily manipulated with conventional magnets. This makes them ideal candidates for use in applications that involve magnetic separation (i.e., heterogeneous catalysis, adsorption of contaminants in aqueous media, etc.).

Corrosion resistance studies of carbon-encapsulated iron nanoparticles

“…Similar findings come from the paper by Schumacher et al, which described that concentrated aqua regia results in severe perforation of carbon coatings and leads to the dissolution of pristinely encapsulated magnetic nanoparticles [13]. Furthermore, Fernandez-Garcia et al [14] studied the stability of carbon-coated nickel nanoparticles embedded in the pores of mesoporous carbon matrix. They demonstrated that 0.1 M HCl does not etch the magnetic phase.…”

“…Moreover, they observed that carbon coating perfectly protected the nickel core from the aerial oxidation even for 36 months. Similarly, Schwickardi et al [15] studied carbon-coated iron nanoparticles surrounded by activated carbon and obtained similar results to paper [14]. The work of Haslam et al [16] also confirmed that thin films formed of nickel nanocrystals encapsulated in carbon had well corrosion stability in hot 1.5 M sulfuric acid.…”

Interplay between microstructure and magnetism in NiO nanoparticles: breakdown of the antiferromagnetic order

“…[1][2][3][4][5][6][7] The growing research activity in this field has been propelled by the development of new chemical routes that allowed the synthesis of NPs with tuneable size distributions and being embedded in different insulating matrices. [8][9][10][11][12][13][14][15][16] It is worth noting that NPs of the same material and similar size but synthetized using different fabrication routes show a strong dependence of the magnetic properties on the morphology, microstructure or the nature of the matrix. 1,8,10,13 Moreover, 3d metal oxide NPs with different core-shell morphologies are also good candidates for a number of applications due to the possibility of tuning the magnetic response and/or the coating with a functional layer.…”

In Situ Confined Growth Based on a Self‐Templating Reduction Strategy of Highly Dispersed Ni Nanoparticles in Hierarchical Yolk–Shell Fe@SiO2 Structures as Efficient Catalysts

“…On the basis of spatially confined stability, the encapsulation of Ni nanoparticles into an individually isolated form within porous supports, such as carbon materials, hollow SiO 2 capsules, or the inner walls of Al 2 O 3 nanotubes, has proved to be an effective strategy to enhance their stability because these porous structures can isolate catalytically active Ni sites to a large extent and dramatically decrease the aggregation and loss of Ni nanoparticles. Moreover, yolk–shell nanostructures, with an inner movable magnetic core or multiple inner movable magnetic cores and an outer hollow shell, have been proven to be good supports for metal nanoparticles due to their facile magnetic recoverability and high specific surface area …”