Boosting the Oxygen Evolution Reaction by Tuning the Interfacial Iron Adsorption on Layered Double Hydroxide

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Optimizing water electrolysis for hydrogen production requires understanding ion-electrode interactions.
• Layered double hydroxides (LDHs) are promising electrode materials, but their performance in oxygen evolution reactions (OER) needs enhancement.

Purpose of the Study:

• To investigate the synergistic effect of electrolyte iron (Fe) and interlayer anions on the OER performance of NiAl-LDHs.
• To elucidate the mechanisms behind improved OER activity in the presence of Fe.

Main Methods:

• Synthesis of NiAl-LDHs with varying interlayer anions (CO3^2-, Cl^-, Br^-).
• Electrochemical testing for OER activity.
• Material characterization using X-ray absorption spectroscopy and electron microscopy.
• In situ electrochemical measurements (SPRDE-ICP-MS) to study ion dissolution.
• First-principles calculations to understand reaction mechanisms.

Main Results:

• NiAl-LDHs with different interlayer anions showed similar OER activity without Fe.
• Fe addition significantly improved OER performance, with LDH-Br > LDH-Cl > LDH-CO3^2-.
• LDH structure remained stable, but halide ions partially dissolved, with less dissolution for Br-intercalated materials.
• Theoretical calculations confirmed thermodynamic preference for Br^- intercalation and stronger Fe(OH)3 adsorption on LDH-Br, enhancing OER.

Conclusions:

• The synergistic effect of electrolyte Fe and interlayer anions, particularly Br^-, significantly enhances OER activity in NiAl-LDHs.
• Reduced halide ion dissolution in LDH-Br contributes to its superior stability and performance.
• These findings offer mechanistic insights for designing advanced layered materials for efficient water electrolysis and hydrogen production.