Modulation of the Electronic Structure of High-Entropy FeCoNiMnAl Layered Double Hydroxides Boosting Oxygen Evolution...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient and durable non-precious metal electrocatalysts are crucial for large-scale hydrogen production via water electrolysis.
• High-entropy materials offer unique properties like synergistic effects and structural stability due to multielement compositions.
• Understanding electronic interactions in high-entropy materials is essential for catalyst design.

Purpose of the Study:

• To synthesize and characterize a pentametallic high-entropy layered double hydroxide (LDH) catalyst for the oxygen evolution reaction (OER).
• To investigate the catalytic performance and stability of the high-entropy LDH catalyst in an alkaline medium.
• To elucidate the underlying electronic mechanisms responsible for the enhanced catalytic activity.

Main Methods:

• In situ synthesis of a pentametallic high-entropy LDH (FeCoNiMnAl) on nickel foam using a one-step hydrothermal method.
• Characterization of the catalyst's structure, morphology, and surface properties.
• Electrochemical testing, including overpotential measurements for OER and performance evaluation in an alkaline anion exchange membrane electrolyzer.
• Theoretical calculations (e.g., DFT) to understand electronic interactions and adsorption mechanisms.

Main Results:

• The synthesized FeCoNiMnAl high-entropy LDH catalyst exhibits a 3D layered microflower structure with a large surface area and heterogeneous interface.
• The catalyst achieves a low overpotential of 242 mV at 100 mA cm⁻² for OER in 1 M KOH.
• An electrolyzer using this catalyst demonstrates a current density of 1 A cm⁻² at 2.02 V and maintains performance for 160 hours.
• Theoretical calculations indicate that multimetal electronic interactions optimize the d-band center, enhancing adsorption of oxygen intermediates.

Conclusions:

• The high-entropy strategy effectively enhances both the activity and stability of LDH catalysts for the oxygen evolution reaction.
• The pentametallic FeCoNiMnAl LDH catalyst shows significant potential for industrial applications in water electrolysis.
• This work provides insights into the electronic structure-property relationships in high-entropy materials for catalysis.