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CoCrFeNi High-Entropy Alloy as an Enhanced Hydrogen Evolution Catalyst in an Acidic Solution
Frank McKay1, Yuxin Fang2, Orhan Kizilkaya3
1Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
High-entropy alloys (HEAs) show promise as electrocatalysts. A CoCrFeNi HEA demonstrated superior performance for the hydrogen evolution reaction (HER) in acidic solutions, attributed to its unique surface oxidation state.
Area of Science:
- Materials Science
- Electrochemistry
- Catalysis
Background:
- High-entropy alloys (HEAs) possess unique properties but their catalytic applications remain underexplored.
- Understanding HEA surface behavior under electrochemical conditions is crucial for catalyst design.
Purpose of the Study:
- To theoretically predict and experimentally validate the surface oxidation and catalytic activity of a CoCrFeNi HEA for the hydrogen evolution reaction (HER).
- To compare the HER performance of the HEA against its constituent metals in acidic media.
Main Methods:
- Theoretical modeling to predict HEA surface oxidation states.
- Electrochemical experiments, including polarization measurements, to evaluate HER activity.
- Surface science techniques to analyze the HEA surface composition and oxidation.
Main Results:
- The CoCrFeNi HEA surface undergoes partial oxidation in acidic solution under cathodic bias, with Nickel (Ni) showing the highest resistance to oxidation.
- The HEA exhibited significantly enhanced HER activity compared to its individual component metals.
- An overpotential of only 60 mV relative to Platinum (Pt) was achieved for the HER at 1 mA/cm² in 0.5 M H₂SO₄.
Conclusions:
- The partially oxidized surface of the CoCrFeNi HEA is highly active for the electrochemical hydrogen evolution reaction.
- HEAs represent a promising class of materials for advanced electrocatalyst development.
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