title: Air-stable superparamagnetic metal nanoparticles entrapped in graphene oxide matrix.
abstract: Superparamagnetism is a phenomenon caused by quantum effects in magnetic nanomaterials. Zero-valent metals with diameters below 5 nm have been suggested as superior alternatives to superparamagnetic metal oxides, having greater superspin magnitudes and lower levels of magnetic disorder. However, synthesis of such nanometals has been hindered by their chemical instability. Here we present a method for preparing air-stable superparamagnetic iron nanoparticles trapped between thermally reduced graphene oxide nanosheets and exhibiting ring-like or core-shell morphologies depending on iron concentration. Importantly, these hybrids show superparamagnetism at room temperature and retain it even at 5 K. The corrected saturation magnetization of 185 Am(2) kg(-1) is among the highest values reported for iron-based superparamagnets. The synthetic concept is generalized exploiting functional groups of graphene oxide to stabilize and entrap cobalt, nickel and gold nanoparticles, potentially opening doors for targeted delivery, magnetic separation and imaging applications.
authors.affiliation: Department of Experimental Physics and Department of Physical Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University in Olomouc, Slechtitelu 27, 783 71 Olomouc, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Tuček
authors.affiliation: Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic.
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Sofer
authors.affiliation: Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bouša
authors.affiliation: Division of Chemistry &Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, Singapore.
authors.forename: Martin
authors.initials: M
authors.lastname: Pumera
authors.affiliation: Department of Experimental Physics and Department of Physical Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University in Olomouc, Slechtitelu 27, 783 71 Olomouc, Czech Republic.
authors.forename: Kateřina
authors.initials: K
authors.lastname: Holá
authors.affiliation: Institute of Scientific Instruments, The Czech Academy of Sciences, Kralovopolska 147, 612 64 Brno, Czech Republic.
authors.forename: Aneta
authors.initials: A
authors.lastname: Malá
authors.affiliation: Department of Experimental Physics and Department of Physical Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University in Olomouc, Slechtitelu 27, 783 71 Olomouc, Czech Republic.
authors.forename: Kateřina
authors.initials: K
authors.lastname: Poláková
authors.affiliation: Department of Experimental Physics and Department of Physical Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University in Olomouc, Slechtitelu 27, 783 71 Olomouc, Czech Republic.
authors.forename: Markéta
authors.initials: M
authors.lastname: Havrdová
authors.affiliation: Department of Experimental Physics and Department of Physical Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University in Olomouc, Slechtitelu 27, 783 71 Olomouc, Czech Republic.
authors.forename: Klára
authors.initials: K
authors.lastname: Čépe
authors.affiliation: Department of Experimental Physics and Department of Physical Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University in Olomouc, Slechtitelu 27, 783 71 Olomouc, Czech Republic.
authors.forename: Ondřej
authors.initials: O
authors.lastname: Tomanec
authors.affiliation: Department of Experimental Physics and Department of Physical Chemistry, Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University in Olomouc, Slechtitelu 27, 783 71 Olomouc, Czech Republic.
authors.forename: Radek
authors.initials: R
authors.lastname: Zbořil