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Symmetric-Waveform Alternating-Current Excitation Enables Full Ni Valence-State Transformation in Co–Ni Catalysts
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DOI：10.1021/acs.langmuir.6c02237.png)
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Abstract
En 中文
The oxygen evolution reaction (OER) is limited by the difficulty of achieving complete oxidation of transition metals to higher valence states, restricting the utilization of their intrinsic activity. Conventional direct-current polarization typically produces mixed-valence surfaces with only partial enrichment of Ni3+ and Co3+. Here, we report a symmetric-waveform alternating-current activation strategy that induces dynamic surface reconstruction, enabling full conversion of Ni2+ into Ni3+ and partial oxidation of Co2+ into Co3+. Experimental characterization confirms the enrichment of high-valence species, while density functional theory calculations reveal that a fully trivalent Ni surface shifts the rate-determining step from *OH adsorption to *OOH adsorption with a reduced barrier. Projected density of states analysis shows Ni d-band centers approaching the Fermi level, facilitating stronger orbital interactions with oxygen intermediates. Charge distribution analyses further indicate enhanced conductivity and electron redistribution. These synergistic effects lower the overpotential at 10 mA cm–2 by 63.6 mV and increase catalytic activity by 12.5%. This work establishes dynamic valence-state engineering via alternating-current activation as a pathway for designing noble-metal-free, high-performance OER catalysts for sustainable hydrogen production.
Keywords:
Catalysts
Electrical properties
Evolution reactions
Radiology
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3.9
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5.4W
Citations:
10.6W
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