title: The role of nano-sized manganese oxides in the oxygen-evolution reactions by manganese complexes: towards a complete picture.
abstract: Eighteen Mn complexes with N-donor and carboxylate ligands have been synthesized and characterized. Three Mn complexes among them are new and are reported for the first time. The reactions of oxygen evolution in the presence of oxone (2KHSO5·KHSO4·K2SO4) and cerium(iv) ammonium nitrate catalyzed by these complexes are studied and characterized by UV-visible spectroscopy, X-ray diffraction spectrometry, dynamic light scattering, Fourier transform infrared spectroscopy, electron paramagnetic resonance spectroscopy, transmission electron microscopy, scanning electron microscopy, membrane-inlet mass spectrometry and electrochemistry. Some of these complexes evolve oxygen in the presence of oxone as a primary oxidant. CO2 and MnO4(-) are other products of these reactions. Based on spectroscopic studies, the true catalysts for oxygen evolution in these reactions are different. We proposed that for the oxygen evolution reactions in the presence of oxone, the true catalysts are both high valent Mn complexes and Mn oxides, but for the reactions in the presence of cerium(iv) ammonium nitrate, the active catalyst is most probably a Mn oxide.
authors.affiliation: Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran. mmnajafpour@iasbs.ac.ir.
authors.forename: Mohammad Mahdi
authors.initials: MM
authors.lastname: Najafpour
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Hołyńska
authors.forename: Amir Nasser
authors.initials: AN
authors.lastname: Shamkhali
authors.forename: Sayed Habib
authors.initials: SH
authors.lastname: Kazemi
authors.forename: Warwick
authors.initials: W
authors.lastname: Hillier
authors.forename: Emad
authors.initials: E
authors.lastname: Amini
authors.forename: M
authors.initials: M
authors.lastname: Ghaemmaghami
authors.forename: Davood
authors.initials: D
authors.lastname: Jafarian Sedigh
authors.forename: Atefeh
authors.initials: A
authors.lastname: Nemati Moghaddam
authors.forename: Rahim
authors.initials: R
authors.lastname: Mohamadi
authors.forename: Sasan
authors.initials: S
authors.lastname: Zaynalpoor
authors.forename: Katrin
authors.initials: K
authors.lastname: Beckmann
mesh_terms: D017895:Manganese Compounds / Q000737:chemistry* / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry* / Q000378:metabolism*; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism*; D014961:X-Ray Diffraction
chemical_list: D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide; D010100:Oxygen