Graphene quantum dots modulated NiFe-LDH for stable seawater electrooxidation

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Nickel-iron layered double hydroxide (NiFe-LDH) is a promising electrocatalyst for the oxygen evolution reaction (OER).
• Seawater electrolysis presents challenges due to competing chlorine evolution reactions and catalyst instability.
• Modifying NiFe-LDH is crucial to enhance its activity and durability in challenging electrochemical environments.

Purpose of the Study:

• To investigate the effect of graphene quantum dots (GQDs) on the seawater OER performance of NiFe-LDH.
• To understand how GQDs regulate the interfacial electronic structure and suppress side reactions.
• To evaluate the optimized NiFe-LDH@GQDs catalyst in an anion exchange membrane (AEM) electrolyzer.

Main Methods:

• Synthesis of NiFe-LDH modified with GQDs (NiFe-LDH@GQDs).
• Electrochemical characterization including OER performance testing in simulated seawater.
• Long-term stability tests at high current densities.
• Assembly and testing of an anion exchange membrane (AEM) electrolyzer.

Main Results:

• GQDs modification effectively regulated the interfacial electronic structure of NiFe-LDH.
• The NiFe-LDH@GQDs catalyst suppressed chlorine evolution side reactions, enhancing OER selectivity.
• The optimal NiFe-LDH@GQDs achieved high OER performance: 100 mA cm^-2 at 241 mV overpotential.
• Exceptional long-term stability was demonstrated, maintaining 700 hours at 1 A cm^-2.
• Excellent performance was observed in an AEM-electrolyzer setup.

Conclusions:

• GQDs are effective modifiers for enhancing NiFe-LDH electrocatalysts for seawater OER.
• The synergistic effect between GQDs and NiFe-LDH improves catalytic activity, selectivity, and stability.
• The developed NiFe-LDH@GQDs catalyst shows significant potential for efficient and durable seawater electrolysis applications.