title: Mechanistic Investigation of Water Oxidation Catalyzed by Uniform, Assembled MnO Nanoparticles.
abstract: The development of active water oxidation catalysts is critical to achieve high efficiency in overall water splitting. Recently, sub-10 nm-sized monodispersed partially oxidized manganese oxide nanoparticles were shown to exhibit not only superior catalytic performance for oxygen evolution, but also unique electrokinetics, as compared to their bulk counterparts. In the present work, the water-oxidizing mechanism of partially oxidized MnO nanoparticles was investigated using integrated in situ spectroscopic and electrokinetic analyses. We successfully demonstrated that, in contrast to previously reported manganese (Mn)-based catalysts, Mn(III) species are stably generated on the surface of MnO nanoparticles via a proton-coupled electron transfer pathway. Furthermore, we confirmed as to MnO nanoparticles that the one-electron oxidation step from Mn(II) to Mn(III) is no longer the rate-determining step for water oxidation and that Mn(IV)═O species are generated as reaction intermediates during catalysis.
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea.
authors.forename: Kyoungsuk
authors.initials: K
authors.lastname: Jin
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea.
authors.forename: Hongmin
authors.initials: H
authors.lastname: Seo
authors.affiliation: Department of Applied Chemistry, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.|Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science (CSRS) , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea.
authors.forename: Mani
authors.initials: M
authors.lastname: Balamurugan
authors.affiliation: Western Seoul Center, Korea Basic Science Institute (KBSI) , 150, Bukahyeon-ro, Seodaemun-gu, Seoul 120-140, Korea.
authors.forename: Donghyuk
authors.identifier: 0000-0002-8289-7725
authors.initials: D
authors.lastname: Jeong
authors.affiliation: Western Seoul Center, Korea Basic Science Institute (KBSI) , 150, Bukahyeon-ro, Seodaemun-gu, Seoul 120-140, Korea.
authors.forename: Yoo Kyung
authors.initials: YK
authors.lastname: Go
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea.
authors.forename: Jung Sug
authors.initials: JS
authors.lastname: Hong
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea.
authors.forename: Kang Hee
authors.initials: KH
authors.lastname: Cho
authors.affiliation: Department of Applied Chemistry, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.|Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science (CSRS) , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Kakizaki
authors.affiliation: Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science (CSRS) , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Nadège
authors.initials: N
authors.lastname: Bonnet-Mercier
authors.affiliation: Pohang Accelerator Laboratory, Pohang University of Science and Technology (POSTECH) , Pohang 790-784, Korea.
authors.forename: Min Gyu
authors.initials: MG
authors.lastname: Kim
authors.affiliation: Western Seoul Center, Korea Basic Science Institute (KBSI) , 150, Bukahyeon-ro, Seodaemun-gu, Seoul 120-140, Korea.
authors.forename: Sun Hee
authors.identifier: 0000-0001-6557-1996
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science (CSRS) , 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Ryuhei
authors.identifier: 0000-0003-0743-8534
authors.initials: R
authors.lastname: Nakamura
authors.affiliation: Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea.
authors.forename: Ki Tae
authors.identifier: 0000-0001-6353-8877
authors.initials: KT
authors.lastname: Nam