Cationic Defect Engineering for Promoting Oxidation of 5-Hydroxymethylfurfural While Passivating OER

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical organic oxidation offers green, energy-efficient industrial advantages.
• The oxygen evolution reaction (OER) competes with organic oxidation, reducing efficiency.
• Developing selective electrocatalysts is crucial for industrial applications.

Purpose of the Study:

• To develop a method for promoting 5-hydroxymethylfurfural oxidation (HMFOR) while suppressing OER.
• To investigate the role of cationic defects in enhancing HMFOR electrocatalysis.
• To provide a strategy for high-performance electrocatalyst design.

Main Methods:

• Etching NiMnFe-layered double hydroxide (LDH) with N,N-dimethylacetamide (DMF) to create cationic defects.
• Utilizing in situ electrochemical impedance spectroscopy to analyze reaction kinetics.
• Employing in situ infrared spectroscopy and theoretical calculations to study reaction pathways.

Main Results:

• The etched NiMnFe-LDH (d-NiMnFe-LDH) showed a 50 mV potential decrease for HMFOR and a 30 mV increase for OER at 50 mA cm⁻².
• d-NiMnFe-LDH exhibited faster kinetics for HMFOR but slower kinetics for OER compared to pristine NiMnFe-LDH.
• Cationic defects were found to enhance intermediate adsorption and lower the reaction energy barrier for HMFOR.

Conclusions:

• DMF etching effectively creates cationic defects in NiMnFe-LDH, promoting HMFOR and suppressing OER.
• The observed changes in reaction kinetics and energy barriers confirm the beneficial role of cationic defects.
• This approach offers a promising strategy for designing industrial electrocatalysts for efficient organic oxidation at high current densities.