Article

Polyoxometalate electrocatalysts based on earth-abundant metals for efficient water oxidation in acidic media

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Abstract

Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions. Specifically, we report the enhanced catalytic activity of insoluble salts of polyoxometalates with caesium or barium counter-cations for oxygen evolution. In particular, the barium salt of a cobalt-phosphotungstate polyanion outperforms the state-of-the-art IrO2 catalyst even at pH < 1, with an overpotential of 189 mV at 1 mA cm–2. In addition, we find that a carbon-paste conducting support with a hydrocarbon binder can improve the stability of metal-oxide catalysts in acidic media by providing a hydrophobic environment.

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Acknowledgements

This work was supported by the European Union (project ERC StG, grant CHEMCOMP, no. 279313), the Spanish Ministerio de Economía y Competitividad (MINECO; through projects CTQ2015-71287-R, CTQ2014-52774-P and the Severo Ochoa Excellence Accreditation 2014-2018 SEV-2013-0319), the Generalitat de Catalunya (2014-SGR-797 and 2014SGR-199) and the CERCA Programme/Generalitat de Catalunya. J.M.P. acknowledges the ICREA Foundation for an ICREA Academia award. M.B.A. acknowledges the Generalitat Catalana (AGAUR) for a predoctoral fellowship. The authors also thank Á. Reyes-Carmona for discussions.

Author information

Author notes

    • Marta Blasco-Ahicart
    •  & Joaquín Soriano-López

    These authors contributed equally to this work.

Affiliations

  1. Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans 16, E-43007 Tarragona, Spain

    • Marta Blasco-Ahicart
    • , Joaquín Soriano-López
    •  & J. R. Galan-Mascaros
  2. Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel.lí Domingo 1, E-43007 Tarragona, Spain

    • Joaquín Soriano-López
    • , Jorge J. Carbó
    •  & Josep M. Poblet
  3. ICREA, Passeig Lluis Companys, 23, E-08010 Barcelona, Spain

    • J. R. Galan-Mascaros

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Contributions

J.R.G.-M. proposed the concept. J.R.G.-M., M.B.-A. and J.S.-L. designed the experiments. M.B.-A. and J.S.-L. performed the experiments. All authors participated in data analysis and co-wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to J. R. Galan-Mascaros.

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