Theory-driven design of high-valence metal sites for water oxidation confirmed using in situ soft X-ray absorption

Xueli Zheng, Bo Zhang*, Phil De Luna, Yufeng Liang, Riccardo Comin, Oleksandr Voznyy, Lili Han, F. Pelayo García De Arquer, Min Liu, Cao Thang Dinh, Tom Regier, James J. Dynes, Sisi He, Huolin L. Xin, Huisheng Peng, David Prendergast, Xiwen Du, Edward H. Sargent

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

479 Scopus citations

Abstract

The efficiency with which renewable fuels and feedstocks are synthesized from electrical sources is limited at present by the sluggish oxygen evolution reaction (OER) in pH-neutral media. We took the view that generating transition-metal sites with high valence at low applied bias should improve the activity of neutral OER catalysts. Here, using density functional theory, we find that the formation energy of desired Ni 4+ sites is systematically modulated by incorporating judicious combinations of Co, Fe and non-metal P. We therefore synthesized NiCoFeP oxyhydroxides and probed their oxidation kinetics with in situ soft X-ray absorption spectroscopy (sXAS). In situ sXAS studies of neutral-pH OER catalysts indicate ready promotion of Ni 4+ under low overpotential conditions. The NiCoFeP catalyst outperforms IrO 2 and retains its performance following 100 h of operation. We showcase NiCoFeP in a membrane-free CO 2 electroreduction system that achieves a 1.99 V cell voltage at 10 mA cm -2, reducing CO 2 into CO and oxidizing H 2 O to O 2 with a 64% electricity-to-chemical-fuel efficiency.

Original languageEnglish (US)
Pages (from-to)149-154
Number of pages6
JournalNature chemistry
Volume10
Issue number2
DOIs
StatePublished - Feb 1 2018

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering

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