title: Green solvent for green materials: a supercritical hydrothermal method and shape-controlled synthesis of Cr-doped CeO2 nanoparticles.
abstract: This paper describes a supercritical hydrothermal synthesis method as a green solvent process, along with products based on this method that can be used as green materials that contribute to solving environmental problems. The first part of this paper summarizes the basics of this method, including the mechanism of the reactions, specific features of the supercritical state for nanoparticle synthesis, the continuous flow-type reactor and applications; this provides a better understanding of the suitability of this method to synthesize green materials. The second part of the paper describes the method used to synthesize Cr-doped CeO(2) nanoparticles, which show an extremely high oxygen storage capacity, suggesting their high potential as an environmental catalyst. Transmission electron microscopy and scanning electron microscope images showed octahedral Cr-doped CeO(2) nanoparticles with sizes of 15-30 nm and cubic Cr-doped CeO(2) nanoparticles with sizes of 5-8 nm. Octahedral Cr-doped CeO(2) nanoparticles exposing (111) facets and cubic Cr-doped CeO(2) nanoparticles exposing (100) facets were determined by high-resolution transmission electron microscopy and selected area electron diffraction. The X-ray diffraction peaks shifted to a high angle because the radius of the Cr ion is smaller than that of the Ce ion.
authors.affiliation: Graduate School of Engineering, Tohoku University, 6-6 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan Japan Society for the Promotion of Science, Tokyo, Japan.
authors.forename: Yuanzheng
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 6-6-10 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Seiichi
authors.initials: S
authors.lastname: Takami
authors.affiliation: New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Gimyeong
authors.initials: G
authors.lastname: Seong
authors.affiliation: New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Dejhosseini
authors.affiliation: Graduate School of Engineering, Tohoku University, 6-6 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Muhammad Zamir
authors.initials: MZ
authors.lastname: Hossain
authors.affiliation: New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Takio
authors.initials: T
authors.lastname: Noguchi
authors.affiliation: Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hojo
authors.affiliation: Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Aoki
authors.affiliation: New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Aida
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 6-6-10 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan ajiri@tagen.tohoku.ac.jp.
authors.forename: Tadafumi
authors.initials: T
authors.lastname: Adschiri
keywords: catalyst; cerium oxide; nanoparticles; oxygen storage capacity; shape control; supercritical