MoZn-based high entropy alloy catalysts enabled dual activation and stabilization in alkaline oxygen evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient electrocatalysts for the oxygen evolution reaction (OER) is crucial but hindered by competing reaction pathways (adsorbed evolution mechanism and lattice oxygen mechanism) leading to performance trade-offs.
• The adsorbed evolution mechanism (AEM) exhibits sluggish kinetics due to linear scaling relationships, while the lattice oxygen mechanism (LOM) is prone to structural instability from lattice oxygen escape.

Purpose of the Study:

• To design and investigate a novel high-entropy alloy (HEA) catalyst that simultaneously promotes high activity and long-term durability for the oxygen evolution reaction (OER).
• To achieve dual activation and stabilization of competing OER pathways by incorporating specific elements into the HEA structure.

Main Methods:

• Computational modeling using Density Functional Theory (DFT) to understand reaction mechanisms and active sites.
• Experimental validation using chemical probe techniques to confirm dual-mechanism activation.
• Electrocatalytic performance testing to evaluate OER activity and durability under demanding conditions.

Main Results:

• A MoZnFeCoNi high-entropy alloy (HEA) was synthesized, incorporating Mo as an AEM promoter and Zn as an LOM activator.
• DFT and experimental results confirmed dual-mechanism activation, with specific sites (Co-Co†-Mo for AEM, Zn-O†-Ni for LOM) facilitating synergistic catalysis.
• The HEA catalyst demonstrated an ultralow OER overpotential (η10 = 221 mV) and remarkable stability, operating for over 1500 hours at 100 mA cm⁻².

Conclusions:

• The developed MoZnFeCoNi HEA effectively enables dual-mechanism synergy for efficient and durable OER catalysis.
• Multielement interactions, the high-entropy structure, and the carbon network contribute significantly to the enhanced structural stability and catalytic performance.
• This work presents a promising strategy for designing advanced HEA electrocatalysts by leveraging dual-mechanism activation and stabilization for challenging reactions like OER.