Corrosion resistance studies of carbon-encapsulated iron nanoparticles

Abstract

The carbon coating in carbon-encapsulated magnetic nanoparticles is considered as a tight and impermeable barrier which should perfectly protect the magnetic core material from external chemical environment. To study the integrity of the coating, carbon-encapsulated iron nanoparticles were subjected to corrosion tests, in which various corrosion agents were used. Several mineral and organic acids, as well as active gaseous environments with various oxidation potential, were applied. Additionally, the corrosion resistance was studied under the so-called galvanic corrosion, using two metal ions (copper and silver) which have higher redox potential than the zero-valent iron. The release of iron from the core as well as the morphology, structural features, chemical composition, and magnetic properties of carbon-encapsulated iron nanoparticles was systematically monitored at each stage of the corrosion process. The largest release of Fe from the encapsulate core was observed when nitric acid was used as the corrosion agent.

Complexes of HArF and AuX (X = F, Cl, Br, I). Comparison of H‐bonds, halogen bonds, F‐shared bonds and covalent bonds

“…[11,12] Gold nanoparticles are an effective green catalyst in chemical and industrial processes, thus coinage metal nanoclusters have attracted increasing attention in numerous fields such as organic catalysis, pharmaceutical chemistry and solar energy collection. [13][14][15] These varied applications of gold nanoparticles are to a great extent attributed to the fact that gold atoms can participate in intermolecular interactions, particularly HBs, [16] where they play the role of a Lewis base. On the other hand, gold also acts as a Lewis acid, much like the hydrogen atom in HBs and the halogen atom in XBs.…”

Regium bonds between Mn clusters (M = Cu, Ag, Au and n = 2–6) and nucleophiles NH3 and HCN

“…Their size, high surface-to-volume ratio, magnetic characteristics, 1 optical, electronic and catalytic properties, 2-4 relatively facile surface functionalization, 5 as well as inhibitory properties against the enlargement of cancer tumors or microbiological diseases 6-12 ignited their scrutiny and spread into many fields of modern science, as distant from each other as searching for new sources to convert solar energy into electricity, heterogeneous catalysis, or targeted anticancer treatment. [13][14][15][16][17][18][19][20][21][22][23][24][25][26] Despite the incontestable importance of NPs, the noncovalent interactions in which they participate has only been studied superficially to this point. In fact, it was only very recently, that the highly intriguing idea of the "regium bond" was introduced by Brinck et al 27 The authors computationally characterized sites on coinage metal atoms (also known as regium) copper, silver, and gold nanoparticles that interacted attractively with a variety of electron-donating molecules.…”

Mechanical Properties and Characterization of Epoxy Composites Containing Highly Entangled As-Received and Acid Treated Carbon Nanotubes

“…Iron catalyst was seen in graphitic “cages” in the as-received CNT. Figure 5 also illustrates that the graphitic cages that once held the iron catalyst have been emptied by perforation of the hot nitric acid and subsequent dissolution of the metallic iron nanoparticles [ 30 , 31 ].…”