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Vacancy-Driven Ni Exsolution in Prussian Blue Analogues Creates Cooperative Defect-Metal Sites for Alkaline Hydrogen
Shiqi Wang1, Haixian Yan1, Hugo L S Santos1
1Department of Chemistry, University of Helsinki, Helsinki, Finland.
Summary
Engineered Prussian blue analogues with programmed vacancies enable efficient alkaline hydrogen evolution. This novel catalyst design enhances stability in saline electrolytes, advancing clean hydrogen production.
Area of Science:
- Materials Science
- Electrochemistry
- Catalysis
Background:
- Alkaline hydrogen evolution reaction (HER) is crucial for clean hydrogen production but faces challenges from slow water dissociation and catalyst instability in saline environments.
- Developing robust and efficient electrocatalysts is essential for overcoming these limitations.
Purpose of the Study:
- To design and synthesize novel multimetallic Prussian blue analogues (PBAs) with programmed vacancies for enhanced alkaline HER.
- To investigate the catalytic mechanism and stability of the engineered PBAs in both alkaline and saline electrolytes.
Main Methods:
- Synthesis of FeMn@CoNi PBAs followed by low-temperature annealing to create hollow nanocages (PBA-350) with exsolved Ni nanoparticles and cyanide vacancies.
- Characterization using operando X-ray diffraction/X-ray absorption spectroscopy (XRD/XAS) and operando impedance spectroscopy.
- Theoretical calculations to elucidate the catalytic mechanism.
- Electrochemical testing in 1.0 m KOH and simulated seawater (1.0 m KOH + 0.5 m NaCl).
Main Results:
- PBA-350 exhibits a dual-site mechanism involving vacancy-stabilized Ni and adjacent Co, optimizing the HER pathway.
- Achieved low overpotential (28.4 mV at 10 mA cm⁻²) and Tafel slope (56 mV dec⁻¹) in 1.0 m KOH.
- Demonstrated remarkable stability over 100 hours at -50 mA cm⁻² in 1.0 m KOH.
- Maintained high performance and stability in simulated seawater by repelling chloride ions via hydration layers.
Conclusions:
- Vacancy-assisted exsolution in PBAs is an effective strategy for designing highly active and stable alkaline HER electrocatalysts.
- The engineered PBA-350 shows promise for efficient and durable hydrogen production, even in challenging saline conditions.
- This work establishes a new design principle for HER catalysts by leveraging defect engineering.
Keywords:
electrocatalysishydrogen evolution reactionmetal‐exsolutionmultimetallic Prussian blue analoguestuned electronic structureMore Related Videos
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