title: Synthesis of MnO2 nanoparticles from sonochemical reduction of MnO4(-) in water under different pH conditions.
abstract: MnO2 was synthesized by sonochemical reduction of MnO4(-) in water under Ar atmosphere at 20°C, where the effects of solution pH on the reduction of MnO4(-) were investigated. The obtained XRD results showed that poor crystallinity δ-MnO2 was formed at pH 2.2, 6.0 and 9.3. When solution pH was increased from 2.2 to 9.3, the morphologies of δ-MnO2 changed from aggregated sheet-like or needle-like structures to spherical nanoparticles and finally to cubic or polyhedron nanoparticles. After further irradiation, MnO2 was readily reduced to Mn(2+). It was confirmed that H2O2 and H atoms formed in the sonolysis of water acted as reductants for both reduction for MnO4(-) to MnO2 and MnO2 to Mn(2+). The optimum irradiation time for the effective synthesis of MnO2 was 13 min at pH 2.2, 9 min at pH 6.0, 8 min at pH 9.3, respectively.
authors.affiliation: Graduate School of Engineering, Osaka Prefecture University, Osaka 599-8531, Japan; State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China; College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046, PR China.
authors.forename: Abulikemu
authors.initials: A
authors.lastname: Abulizi
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Guo Hai
authors.initials: GH
authors.lastname: Yang
authors.affiliation: Graduate School of Engineering, Osaka Prefecture University, Osaka 599-8531, Japan. Electronic address: okitsu@mtr.osakafu-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Okitsu
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China. Electronic address: jjzhu@nju.edu.cn.
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Zhu
keywords: Effect of pH; Manganese dioxide; Permanganate; Sonochemical reduction