Synergistic spin effects in medium-entropy Ni-Fe-Mn-Ce oxyhydroxides for seawater oxidation

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Efficient oxygen evolution reaction (OER) electrocatalysis is crucial for sustainable energy technologies like seawater electrolysis.
• Developing durable and high-performance catalysts is essential to overcome the challenges of OER in alkaline environments.

Purpose of the Study:

• To construct and investigate a high-performance Ni-Fe-Mn-Ce medium-entropy oxyhydroxide catalyst for oxygen evolution reaction (OER) in seawater electrolysis.
• To elucidate the role of cerium (Ce) as a fourth-metal element in optimizing the catalyst's electronic structure and reaction energetics using DFT.

Main Methods:

• In situ electrochemical reconstruction strategy for catalyst synthesis.
• Density functional theory (DFT) calculations to investigate the electronic structure and reaction energetics of various fourth-metal elements.
• Operando spectroscopic characterizations to analyze dynamic valence evolution and charge redistribution.

Main Results:

• The Ni-Fe-Mn-Ce catalyst achieved an overpotential of 183 mV at 10 mA cm^-2 in 1 M KOH and 224 mV in alkaline seawater.
• The catalyst demonstrated excellent resistance to chloride (Cl^-) corrosion.
• DFT revealed Ce's unique advantages in optimizing intermediate adsorption and lowering theoretical overpotential.
• Operando studies showed dynamic valence changes and charge redistribution enhancing intermediate adsorption and electron transfer.

Conclusions:

• Entropy engineering combined with theoretical guidance is a promising approach for developing advanced multi-metallic electrocatalysts.
• The Ni-Fe-Mn-Ce oxyhydroxide catalyst exhibits high efficiency and durability for seawater splitting.
• Optimized electronic structure, including a favorable d-band center and spin polarization, enhances OER kinetics.