Mn3O4@CoMn2O4-CoxOy nanoparticles : partial cation exchange synthesis and electrocatalytic properties toward the oxygen reduction and evolution reactions

Mn3O4@CoMn2O4 nanoparticles (NPs) were produced at low temperature and ambient atmosphere using a one -pot two-step synthesis protocol involving the cation exchange of Mn by Co in preformed Mn3O4 NPs. Selecting the proper cobalt precursor, the nucleation of CoxOy crystallites at the Mn3O4@a CoMn2O4 surface could be simultaneously promoted to form Mn3O4@CoMn2O4-CoxOy NPs. Such heterostructured NPs were investigated for oxygen reduction and evolution reactions (ORR, OER) in alkaline solution. Mn3O4@ CoMn2O4-Cox0y NPs with [Co]/[Mn] = 1 showed low overpotentials of 0.31 Vat(-3) mA.cm(-2) and a small Tafel slope of 52 mV.dec(-1) for ORR, and overpotentials of 0.31 V at 10 mAPeer ReviewedPostprint (author's final draft

Mn3O4@CoMn2O4-CoxOy nanoparticles: partial cation exchange synthesis and electrocatalytic properties toward the oxygen reduction and evolution reactions

et al.MnO@CoMnO nanoparticles (NPs) were produced at low temperature and ambient atmosphere using a one-pot two-step synthesis protocol involving the cation exchange of Mn by Co in preformed MnO NPs. Selecting the proper cobalt precursor, the nucleation of CoO crystallites at the MnO@CoMnO surface could be simultaneously promoted to form MnO@CoMnO-CoO NPs. Such heterostructured NPs were investigated for oxygen reduction and evolution reactions (ORR, OER) in alkaline solution. MnO@CoMnO-CoO NPs with [Co]/[Mn] = 1 showed low overpotentials of 0.31 V at -3 mA·cm and a small Tafel slope of 52 mV·dec for ORR, and overpotentials of 0.31 V at 10 mA·cm and a Tafel slope of 81 mV·dec for OER, thus outperforming commercial Pt-, IrO-based and previously reported transition metal oxides. This cation-exchange-based synthesis protocol opens up a new approach to design novel heterostructured NPs as efficient nonprecious metal bifunctional oxygen catalysts.This work was supported by the European Regional Development Funds and the Spanish MINECO projects BOOSTER (ENE2013-46624-C4-3-R), TNT-FUELS (MAT2014-59961), e-TNT (MAT2014-59961-C2-2-R) and PEC-CO2 (ENE2012-3651). Z.L. and Y.L. thank the China Scholarship Council for scholarship support. E.I. thanks AGAUR for his Ph.D. grant (FI-2013-B-00769). M.I. thanks AGAUR for the Beatriu de Pinos postdoctoral grant (2013 BP-A00344). S.M. acknowledges funding from “Programa Internacional de Becas ‘la Caixa’-Severo Ochoa”. J.L. is a Serra Hunter Fellow and is grateful to ICREA Academia program. We also acknowledge the funding from Generalitat de Catalunya 2014 SGR 1638.Peer Reviewe