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Issue 44, 2020
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Iron-regulated NiPS for enhanced oxygen evolution efficiency

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Abstract

Development of robust and highly active electrocatalysts for the oxygen evolution reaction (OER) is of significance for next-generation renewable energy storage and conversion. Herein, for the first time, we report pyrite-type iron nickel monophosphosulfide (Ni1−xFexPS, x = 0, 0.1, 0.15, 0.2) electrocatalysts with exceptional OER efficiency and stability under alkaline conditions. Ni0.85Fe0.15PS/NF exhibits a considerably low overpotential of 251 (314) mV at 10 (100) mA cm−2 with a Tafel slope of 34 mV dec−1, together with remarkable stability. Moderate Fe regulation in NiPS (Ni0.85Fe0.15PS) is found to stimulate the activation of high-valence-state Ni/Fe oxyhydroxides during the irreversible surface reconstructions that form disordered MOOH@MxSOy@MxPOy surfaces under OER conditions, as is established by microstructural observations, surface-sensitive X-ray photoelectron spectroscopy, Raman spectroscopy and X-ray absorption spectroscopy. DFT calculations show that the catalytic sites formed by Fe doping are more nucleophilic than the Ni sites and thus more OER active, due to a facile Fe(II) → Fe(III) oxidation state change for Fe. Meanwhile, overly stable OER surface species are not formed, as Fe in oxidation states higher than Fe(III) is not favorable, which leads to a lower barrier for the rate-limiting OER step than that for the Ni site. The present results shed light on the design and development of high-performance electrocatalysts in ternary metal monophosphosulfides, as well as providing a fundamental understanding of their intrinsic active sites.

Graphical abstract: Iron-regulated NiPS for enhanced oxygen evolution efficiency

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Supplementary files

Article information


Submitted
18 Aug 2020
Accepted
20 Oct 2020
First published
20 Oct 2020

J. Mater. Chem. A, 2020,8, 23580-23589
Article type
Paper

Iron-regulated NiPS for enhanced oxygen evolution efficiency

W. Peng, J. Li, K. Shen, L. Zheng, H. Tang, Y. Gong, J. Zhou, N. Chen, S. Zhao, M. Chen, F. Gao and H. Gou, J. Mater. Chem. A, 2020, 8, 23580
DOI: 10.1039/D0TA08123J

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