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Valence-State Effect of Iridium Dopant in NiFe(OH) Catalyst for Hydrogen Evolution Reaction. | LitMetric

Valence-State Effect of Iridium Dopant in NiFe(OH) Catalyst for Hydrogen Evolution Reaction.

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Institute of New-Energy Materials, School of Materials Science and Engineering, Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin, 300072, China.

Published: May 2021

AI Article Synopsis

  • Engineering high-performance electrocatalysts is essential for effective energy conversion and storage, with element doping being a key strategy to enhance catalytic activity.
  • The study finds that the valence state of doping elements, particularly trivalent versus tetravalent iridium in nickel-iron layer double hydroxide (NiFe-LDH), significantly influences catalytic performance—trivalent iridium improves hydrogen evolution reaction efficiency better than its tetravalent counterpart.
  • The research indicates that the valence state affects electron donation to oxygen, enhancing water dissociation and hydrogen release, and this effect is also observed with other dopants like ruthenium and platinum, highlighting its importance in optimizing catalysts.

Article Abstract

Engineering high-performance electrocatalysts is of great importance for energy conversion and storage. As an efficient strategy, element doping has long been adopted to improve catalytic activity, however, it has not been clarified how the valence state of dopant affects the catalytic mechanism and properties. Herein, it is reported that the valence state of a doping element plays a crucial role in improving catalytic performance. Specifically, in the case of iridium doped nickel-iron layer double hydroxide (NiFe-LDH), trivalent iridium ions (Ir ) can boost hydrogen evolution reaction (HER) more efficiently than tetravalent iridium (Ir ) ions. Ir -doped NiFe-LDH delivers an ultralow overpotential (19 mV @ 10 mA cm ) for HER, which is superior to Ir doped NiFe-LDH (44 mV@10 mA cm ) and even commercial Pt/C catalyst (40 mV@ 10 mA cm ), and reaches the highest level ever reported for NiFe-LDH-based catalysts. Theoretical and experimental analyses reveal that Ir ions donate more electrons to their neighboring O atoms than Ir ions, which facilitates the water dissociation and hydrogen desorption, eventually boosting HER. The same valence-state effect is found for Ru and Pt dopants in NiFe-LDH, implying that chemical valence state should be considered as a common factor in modulating catalytic performance.

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Source
http://dx.doi.org/10.1002/smll.202100203DOI Listing

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