title: Synthetic routes contaminate graphene materials with a whole spectrum of unanticipated metallic elements.
abstract: The synthesis of graphene materials is typically carried out by oxidizing graphite to graphite oxide followed by a reduction process. Numerous methods exist for both the oxidation and reduction steps, which causes unpredictable contamination from metallic impurities into the final material. These impurities are known to have considerable impact on the properties of graphene materials. We synthesized several reduced graphene oxides from extremely pure graphite using several popular oxidation and reduction methods and tracked the concentrations of metallic impurities at each stage of synthesis. We show that different combinations of oxidation and reduction introduce varying types as well as amounts of metallic elements into the graphene materials, and their origin can be traced to impurities within the chemical reagents used during synthesis. These metallic impurities are able to alter the graphene materials' electrochemical properties significantly and have wide-reaching implications on the potential applications of graphene materials.
authors.affiliation: Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371;
authors.forename: Colin Hong An
authors.initials: CH
authors.lastname: Wong
authors.affiliation: Department of Inorganic Chemistry, Institute of Chemical Technology, 166 28 Prague 6, Czech Republic;
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Sofer
authors.affiliation: Department of Nuclear Spectroscopy, Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, 250 68 Řež, Czech Republic; and.
authors.forename: Marie
authors.initials: M
authors.lastname: Kubešová
authors.affiliation: Department of Nuclear Spectroscopy, Nuclear Physics Institute of the Academy of Sciences of the Czech Republic, 250 68 Řež, Czech Republic; and.
authors.forename: Jan
authors.initials: J
authors.lastname: Kučera
authors.affiliation: Central Analytical Laboratory, Institute of Organic Chemistry and Biochemistry of the Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic.
authors.forename: Stanislava
authors.initials: S
authors.lastname: Matějková
authors.affiliation: Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371; pumera.research@gmail.com.
authors.forename: Martin
authors.initials: M
authors.lastname: Pumera