Engineering Co-ion vacancy in dynamically reconstructed Co-based catalysts for practical anion-exchange membrane...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing robust electrocatalysts is crucial for efficient water electrolysis.
• Metal-ion vacancies can enhance electrocatalyst performance but are challenging to engineer under operating conditions.

Purpose of the Study:

• To develop a strategy for fabricating cobalt (Co)-vacancy-enriched electrocatalysts using strontium (Sr)-ion-mediated dynamic reconstruction.
• To investigate the role of Co-ion vacancies in activating and refilling lattice oxygen for improved electrocatalytic activity.

Main Methods:

• Fabrication of Co-vacancy-enriched Sr-CoOOH nanosheets via Sr-ion-mediated reconstruction.
• In-situ analysis of catalyst reconstruction under oxygen evolution reaction (OER) conditions.
• Electrochemical testing of the fabricated catalyst in anion-exchange membrane water electrolysis.

Main Results:

• The Sr-ion substitution facilitated the formation of Co-ion vacancies in reconstructed oxyhydroxides.
• These vacancies enhanced Co-O covalency, activating lattice oxygen and improving hydroxyl affinity for oxygen refilling.
• The optimized water electrolyzer achieved a high current density (3.3 A cm⁻²) at 2.0 V with low energy consumption (43.5 kWh kg⁻¹ H₂) and excellent stability (0.10 mV h⁻¹ degradation over 1000 h).

Conclusions:

• Sr-ion-mediated reconstruction is an effective strategy for engineering metal-ion vacancies in dynamic electrocatalysts.
• The developed Co-vacancy-enriched Sr-CoOOH nanosheets demonstrate superior performance and durability for water electrolysis.
• This approach provides a guideline for designing targeted electrocatalysts under practical operating conditions.