Operando unraveling photothermal-promoted dynamic active-sites generation in NiFe2O4 for markedly enhanced oxygen evolution

Likun Gao, Xun Cui, Zewei Wang, Christopher D. Sewell, Zili Li, Shuang Liang, Mingyue Zhang, Jian Li, Yingjie Hu, Zhiqun Lin

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117 Scopus citations

Abstract

The ability to develop highly active and low-cost electrocatalysts represents an important endeavor toward accelerating sluggish water-oxidation kinetics. Herein, we report the implementation and unraveling of the photothermal effect of spinel nanoparticles (NPs) on promoting dynamic active-sites generation to markedly enhance their oxygen evolution reaction (OER) activity via an integrated operando Raman and density functional theory (DFT) study. Specifically, NiFe2O4 (NFO) NPs are first synthesized by capitalizing on amphiphilic star-like diblock copolymers as nanoreactors. Upon the near-infrared light irradiation, the photothermal heating of the NFO-based electrode progressively raises the temperature, accompanied by a marked decrease of overpotential. Accordingly, only an overpotential of 309 mV is required to yield a high current density of 100 mA cm−2, greatly lower than recently reported earth-abundant electrocatalysts. More importantly, the photothermal effect of NFO NPs facilitates surface reconstruction into high-active oxyhydroxides at lower potential (1.36 V) under OER conditions, as revealed by operando Raman spectroelectrochemistry. The DFT calculation corroborates that these reconstructed (Ni,Fe)oxyhydroxides are electrocatalytically active sites as the kinetics barrier is largely reduced over pure NFO without surface reconstruction. Given the diversity of materials (metal oxides, sulfides, phosphides, etc.) possessing the photo-to-thermal conversion, this effect may thus provide a unique and robust platform to boost highly active surface species in nanomaterials for a fundamental understanding of enhanced performance that may underpin future advances in electrocatalysis, photocatalysis, solar-energy conversion, and renewable-energy production.

Original languageEnglish
Article numbere2023421118
JournalProceedings of the National Academy of Sciences of the United States of America
Volume118
Issue number7
DOIs
StatePublished - 16 Feb 2021

Bibliographical note

Funding Information:
ACKNOWLEDGMENTS. This work is supported by Air Force Office of Scientific Research Grant FA9550-19-1-0317. L.G. acknowledges financial support from the China Scholarship Council.

Publisher Copyright:
© 2021 National Academy of Sciences. All rights reserved.

Keywords

  • Nanoreactor | photothermal effect | operando Raman | dynamic surface reconstruction | density functional theory

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