High-Entropy Environments Enable Metal Surface-Catalyzed Nucleophilic Electrooxidation.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical biomass conversion is a sustainable method for producing valuable chemicals.
• Conventional catalysts for 5-hydroxymethylfurfural electrooxidation (HMFOR) exhibit limitations like poor conductivity and stability.
• Developing efficient and stable catalysts is crucial for advancing biomass valorization.

Purpose of the Study:

• To develop a novel catalyst for efficient electrochemical conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA).
• To address the limitations of existing HMFOR catalysts by enhancing conductivity, stability, and active site utilization.
• To investigate the catalytic mechanism and electronic properties of the novel catalyst.

Main Methods:

• Synthesis and characterization of a Cobalt-Nickel-Manganese-Molybdenum-Palladium (CoNiMnMoPd) high entropy alloy (HEA) catalyst.
• Electrochemical performance evaluation of the HEA catalyst for HMFOR, including conversion, selectivity, and stability tests.
• Experimental and theoretical studies (e.g., DFT calculations) to elucidate the reaction mechanism and the role of the HEA composition.

Main Results:

• The CoNiMnMoPd HEA catalyst demonstrated high performance: 92.5% Faradaic efficiency for FDCA, 89.5% HMF conversion, and 95.8% FDCA selectivity.
• The catalyst maintained excellent performance for over 100 hours, indicating superior stability.
• Investigations revealed that the HEA structure facilitates a high Ni oxidation state and optimizes the energy barrier for the rate-determining step in HMF-to-FDCA conversion.

Conclusions:

• The developed CoNiMnMoPd HEA catalyst significantly overcomes the limitations of traditional HMFOR catalysts.
• The multielement composition of the HEA plays a critical role in enhancing catalytic activity, stability, and selectivity.
• This study provides valuable insights for designing advanced Ni-based HEA catalysts for sustainable biomass valorization.