Recent advances in high-entropy alloys for electrochemical hydrogen evolution, oxygen reduction, and CO₂ reduction reactions

The global transition toward sustainable energy hinges on efficient electrochemical technologies such as fuel cells, water electrolyzers, and CO₂ electrolysis. These devices rely heavily on catalysts to drive key reactions like hydrogen evolution (HER), oxygen reduction (ORR), and CO₂ reduction (CO₂RR). However, conventional catalysts—often based on scarce and expensive platinum-group metals—face limitations in activity, selectivity, and durability. High-entropy alloys (HEAs), a novel class of materials composed of five or more principal elements, have emerged as game-changers due to their tunable electronic structures, synergistic active sites, and exceptional stability under harsh electrochemical conditions.

This comprehensive review, led by researchers at Fuzhou University, China, systematically examines the latest breakthroughs in HEA electrocatalysts. The study delves into:

1. Structural Advantages: Multi-element synergy creates diverse active sites, lattice distortion optimizes adsorption energies, and the "high-entropy effect" enhances corrosion resistance.
2. Synthesis Innovations: Advanced methods like carbothermal shock (CTS), wet-chemistry, and non-equilibrium pyrolysis enable precise control over HEA nanoparticle size, morphology, and composition.
3. Characterization Breakthroughs: Cutting-edge techniques such as atomic electron tomography (AET) and in situ X-ray absorption spectroscopy (XAS) reveal 3D atomic arrangements and dynamic reaction mechanisms.
4. Performance Metrics: HEAs demonstrate record-breaking activity in ORR (half-wave potential up to 0.92 V vs. RHE), HER (overpotential as low as 10.8 mV at 10 mA/cm²), and CO₂RR (Faradaic efficiency >98% for formate production).

Key Findings:

• ORR: PtFeCoNiMn/OMC catalysts achieve 3.7× higher mass activity than commercial Pt/C, with negligible degradation after 30,000 cycles.
• HER: PtFeCoNiCu catalysts achieve an overpotential of 10.8 mV at 10 mA/cm²and 4.6× higher ECSA-normalized activity than commercial Pt/C.
• CO₂RR: PdCuAuAgBiIn aerogels convert CO₂ to formate with 98.1% selectivity at 200 mA/cm², surpassing single-metal catalysts by 10-fold.

This work positions HEAs as a transformative platform for next-generation electrocatalysts, offering a pathway to replace scarce noble metals while exceeding their performance. By integrating machine learning and high-throughput experimentation, the study accelerates the discovery of cost-effective, durable catalysts for renewable energy storage and carbon-neutral fuel production.