Synthesis of carbon-encapsulated iron nanoparticles via solid state reduction of iron oxide nanoparticles

Synthesis and characterization of graphite-encapsulated iron nanoparticles from ball milling-assisted low-pressure chemical vapor deposition

“…It had been previously reported that several Fe-containing phases including BCC Fe, Fe 3 O 4 , FeO and Fe 0.96 O (non-stoichiometric FeO) were found as reaction products of α-Fe 2 O 3 (70 wt.% of the overall sample) and carbon black/carbon nanoparticles/graphite powders (30 wt.% of the overall sample) at 1000°C for 3 h in N 2 gas [29]. Since the LPCVD reaction in our experiments was not interrupted at shorter time intervals, it is unclear whether the reduction mechanism of Fe 2 O 3 includes magnetite (Fe 3 O 4 ) and wustite (FeO) transition phases prior to fully reduced BCC Fe.…”

“…In the reported literature, the utilized steps for obtaining only CEMNPs free of non-encapsulated ones contained a conventional method of overnight HCl leaching (which dissolves Fe and Fe oxides) and removal of leaching solution by sonication, centrifugation, decantation, washing and drying [17–19,28,29,32,36,39]. In the present study, purification was conducted primarily to remove possible stoichiometric or non-stoichiometric iron oxides which were not completely reduced during LPCVD.…”

“…Methods such as carbon arc discharge [9,24–26], solid-state synthesis from iron chelates under H 2 /N 2 /O 2 flows [15], flame spray synthesis [27], pulsed Nd:YAG laser irradiation [4], mechanically activated annealing [10], radio frequency (RF) thermal plasma jet method [18,19,28], solid-state carbothermal reduction [29], spray pyrolysis [30], arc plasma and combustion synthesis/explosion [31,32], microwave-arcing-induced synthesis [33], autoclave synthesis [34], ion-beam sputtering [35] and hydrothermal reaction [36] have been used starting from various raw materials. The carbon encapsulant could be in the amorphous or graphitic form, depending on the source, reaction temperature and interaction of carbon and core starting materials [24–36].…”

“…Thus, a mandatory purification step containing leaching (e.g. in hot HCl solution), filtering, washing (with distilled water and/or ethanol) and drying treatments is conducted to remove the non-encapsulated particles [17–19,28,29,32,36]. …”

Synthesis and characterization of Fe/C core–shell nanoparticles

“…To date, various methods have been proposed for the fabrication of carbon-encapsulated magnetic metal nanoparticles (CEMMNP), including arc discharge methods [10], chemical vapor deposition (CVD) [11], carbothermal reduction methods [12], detonation methods [13], laser ablation techniques [14], thermal radio frequency plasma technique [15], magnetron and ion-beam co-sputtering [16], pyrolysis of organometallic compounds [17], catalytic decomposition of hydrocarbons [18] and hydrothermal solution method [3], etc.…”