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Direct magnetic enhancement of electrocatalytic water oxidation in alkaline media

Abstract

Industrially profitable water splitting is one of the great challenges in the development of a viable and sustainable hydrogen economy. Alkaline electrolysers using Earth-abundant catalysts remain the most economically viable route to electrolytic hydrogen, but improved efficiency is desirable. Recently, electron spin polarization was described as a potential way to improve water-splitting catalysis. Here, we report the significant enhancement of alkaline water electrolysis when a moderate magnetic field (≤450 mT) is applied to the anode. Current density increments above 100% (over 100 mA cm−2) were found for highly magnetic electrocatalysts, such as the mixed oxide NiZnFe4Ox. Magnetic enhancement works even for decorated Ni–foam electrodes with very high current densities, improving their intrinsic activity by about 40% to reach over 1 A cm−2 at low overpotentials. Thanks to its simplicity, our discovery opens opportunities for implementing magnetic enhancement in water splitting.

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All experimental data generated or analysed during this study are included in this published article and its Supplementary Information files.

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Acknowledgements

This work was funded by: the European Union’s Horizon 2020 research and innovation programme under grant agreement CREATE number 721065; FEDER/Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación/RTI2018-095618-B-I0; and the Generalitat de Catalunya (2017-SGR-1406 and the CERCA Programme). The authors also acknowledge BSC-RES for computational resources.

Author information

J.R.G.-M. and N.L. proposed the concept. F.A.G.-P. and J.R.G.-M. designed the experiments. M.B.-A. and F.A.G.-P. performed the synthesis, processing and electrochemical experiments. D.N.-C. performed the magnetic measurements and analyses. N.L. performed the computational studies. All authors wrote the manuscript.

Correspondence to José Ramón Galán-Mascarós.

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Supplementary information

Supplementary Information

Supplementary methods, discussion, Figs. 1–18, Tables 1 and 2, and references

Supplementary Video 1

Water electrolysis enhancement on approaching a permanent magnet to a Ni–foam/NiZnFe4Ox-decorated anode working at a constant voltage of 1.67 V versus RHE in a single cell.

Supplementary Video 2

Water electrolysis enhancement on approaching a permanent magnet to a Ni–foam/NiZnFeOx-decorated anode working at 100 mA cm−2 in a single cell.

Supplementary Video 3

Anodic current enhancement on approaching a permanent magnet to a Ni–foam/NiZnFeOx-decorated anode working at 10 mA cm−2 in a H cell.

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Fig. 1: Magnetic effect on water electrolysis with a bare Ni–foam anode.
Fig. 2: Polarization data under an applied magnetic field for different OER catalysts.
Fig. 3: Magnetic enhancement of water electrolysis under an applied magnetic field.
Fig. 4: Polarization data for surface-modified Ni–foam anodes.