Sustainable oxygen evolution electrocatalysis in aqueous 1 MH2SO4 with earth abundant nanostructured Co3O4

Earth-abundant electrocatalysts for the oxygen evolution reaction (OER) able to work in acidic working conditions are elusive. While many first-row transition metal oxides are competitive in alkaline media, most of them just dissolve or become inactive at high proton concentrations where hydrogen evolution is preferred. Only noble-metal catalysts, such as IrO2, are fast and stable enough in acidic media. Herein, we report the excellent activity and long-term stability of Co3O4-based anodes in 1 M H2SO4 (pH 0.1) when processed in a partially hydrophobic carbon-based protecting matrix. These Co3O4@C composites reliably drive O2 evolution a 10 mA cm–2 current density for >40 h without appearance of performance fatigue, successfully passing benchmarking protocols without incorporating noble metals. Our strategy opens an alternative venue towards fast, energy efficient acid-media water oxidation electrodes.The authors thank the support from projects RED2018-102459-T, RTI2018-095618-B-I00, PID2020-116093RB-C41,C43&C44, PID2019-107338RB-C63 and PID2020-114252GB-I00 funded by MCIN/AEI/10.13039/501100011033/ and by “ERDF A way of making Europe”; the Generalitat de Catalunya (2017-SGR-1406 and 2017-SGR-327), and the Basque Government (grant IT1591-22). J.Y. thanks the China Scholarship Council (CSC) for predoctoral fellowships (File No. 201806270234). S.B. acknowledges Grant RYC-2017-21931 funded by MCIN/AEI/ 10.13039/501100011033 and by ESF Investing in your future, and UPV/EHU project EHUrOPE19/01 and IKERBASQUE, Basque Foundation for Science. ICIQ and ICN2 are supported by the Ministerio de Ciencia e Innovación through the Severo Ochoa Excellence Accreditations CEX2019-000925-S (MIC/AEI) and SEV-2017-0706; and by the CERCA Programme/Generalitat de Catalunya. M.C.S. has received funding from the European Union’s Horizon 2020 research and innovation programme under Marie Skodowska-Curie grant 754510 (PROBIST) and the Severo Ochoa programme. M.C.S. has received funding from the postdoctoral fellowship Juan de la Cierva Incorporation from MICINN (JCI-2019) and the Severo Ochoa programme. M.P.D. acknowledges funding for a Ph.D. fellowship from the MPC Foundation.Peer reviewe