title: Surface decoration of amine-rich carbon nitride with iron nanoparticles for arsenite (As(III)) uptake: The evolution of the Fe-phases under ambient conditions.
abstract: A novel hybrid material (gC3N4-rFe) consisting of amine-rich graphitic carbon nitride (gC3N4), decorated with reduced iron nanoparticles (rFe) is presented. XRD and TEM show that gC3N4-rFe bears aggregation-free Fe-nanoparticles (10nm) uniformly dispersed over the gC3N4 surface. In contrast, non-supported iron nanoparticles are strongly aggregated, with non-uniform size distribution (20-100nm). (57)Fe-Mössbauer spectroscopy, dual-mode electron paramagnetic resonance (EPR) and magnetization measurements, allow a detailed mapping of the evolution of the Fe-phases after exposure to ambient O2. The as-prepared gC3N4-rFe bears Fe(2+) and Fe° phases, however only after long exposure to ambient O2, a Fe-oxide layer is formed around the Fe° core. In this [Fe°/Fe-oxide] core-shell configuration, the gC3N4-rFe hybrid shows enhanced As(III) uptake capacity of 76.5mgg(-1), i.e., ca 90% higher than the unmodified carbonaceous support, and 300% higher than the non-supported Fe-nanoparticles. gC3N4-rFe is a superior As(III) sorbent i.e., compared to its single counterparts or vs. graphite/graphite oxide or activated carbon analogues (11-36mgg(-1)). The present results demonstrate that the gC3N4 matrix is not simply a net that holds the particles, but rather an active component that determines particle formation dynamics and ultimately their redox profile, size and surface dispersion homogeneity.
authors.affiliation: Physics Department, University of Ioannina, Ioannina 45110, Greece. Electronic address: yiannisgeorgiou@hotmail.com.
authors.forename: Y
authors.initials: Y
authors.lastname: Georgiou
authors.affiliation: Physics Department, University of Ioannina, Ioannina 45110, Greece. Electronic address: emouzou@cc.uoi.gr.
authors.forename: E
authors.initials: E
authors.lastname: Mouzourakis
authors.affiliation: Physics Department, University of Ioannina, Ioannina 45110, Greece; Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry and Experimental Physics, Palacky University in Olomouc, 77146, Czech Republic. Electronic address: bourlino@cc.uoi.gr.
authors.forename: A B
authors.initials: AB
authors.lastname: Bourlinos
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry and Experimental Physics, Palacky University in Olomouc, 77146, Czech Republic. Electronic address: radek.zboril@upol.cz.
authors.forename: R
authors.initials: R
authors.lastname: Zboril
authors.affiliation: Department of Materials Science and Engineering, University of Ioannina, Ioannina 45110, Greece. Electronic address: mkarakas@cc.uoi.gr.
authors.forename: M A
authors.initials: MA
authors.lastname: Karakassides
authors.affiliation: Physics Department, University of Ioannina, Ioannina 45110, Greece. Electronic address: adouval@uoi.gr.
authors.forename: A P
authors.initials: AP
authors.lastname: Douvalis
authors.affiliation: Physics Department, University of Ioannina, Ioannina 45110, Greece. Electronic address: tbakas@cc.uoi.gr.
authors.forename: Th
authors.initials: T
authors.lastname: Bakas
authors.affiliation: Physics Department, University of Ioannina, Ioannina 45110, Greece. Electronic address: ideligia@cc.uoi.gr.
authors.forename: Y
authors.initials: Y
authors.lastname: Deligiannakis
keywords: Arsenite; Carbon nitride; Dual mode EPR; Fe amorphous nanoparticles; Fe(2+)/Fe(3+)-oxide; Mössbauer spectroscopy