Graphene quantum dots modulated NiFe-LDH for stable seawater electrooxidation

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Nickel-iron layered double hydroxides (NiFe-LDH) are promising electrocatalysts for the oxygen evolution reaction (OER).
• Seawater electrolysis presents challenges due to high chloride content, leading to catalyst degradation and side reactions.
• Optimizing catalyst interfaces is key to enhancing OER performance in harsh environments.

Purpose of the Study:

• To investigate the effect of graphene quantum dots (GQDs) modification on NiFe-LDH for seawater OER.
• To understand how GQDs regulate the interfacial electronic structure of NiFe-LDH.
• To assess the enhanced OER performance and stability of the modified catalyst in simulated seawater.

Main Methods:

• Synthesis of NiFe-LDH modified with GQDs (NiFe-LDH@GQDs).
• Electrochemical characterization including cyclic voltammetry and chronoamperometry.
• Electrolyzer testing to evaluate performance in an alkaline medium.

Main Results:

• NiFe-LDH@GQDs demonstrated enhanced OER activity, achieving 100 mA cm^-2 at an overpotential of 241 mV.
• The catalyst exhibited remarkable stability, maintaining performance for 700 hours at a high current density of 1 A cm^-2.
• The modification effectively suppressed chlorine evolution and improved selectivity towards OER.

Conclusions:

• GQD modification significantly enhances the seawater OER performance of NiFe-LDH.
• Regulating the interfacial electronic structure and suppressing side reactions are key mechanisms for improvement.
• The optimized NiFe-LDH@GQDs show potential for practical applications in alkaline anion exchange membrane (AEM) electrolyzers.