Ligand-Intercalated MOFs Enable Reaction-Pathway Engineering in Biomass Electrooxidation via Steric and π-Electronic...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrocatalytic biomass upgrading is crucial for sustainable chemistry but faces challenges in controlling reaction pathways due to coupled mass transport, adsorption, and kinetics.
• Layered metal-organic frameworks (MOFs) offer potential for catalysis, but precise control over their internal microenvironments is difficult.

Purpose of the Study:

• To develop a strategy for selective reaction-pathway engineering in electrocatalytic biomass upgrading.
• To decouple the effects of steric and electronic microenvironments within MOFs to independently tune reaction parameters.
• To demonstrate enhanced performance in biomass valorization through controlled catalyst design.

Main Methods:

• A ligand-intercalation strategy was employed using aromatic dicarboxylate ligands of varying lengths and π-electron densities into NiCo-based MOFs.
• Tunable interlayer nanochannels were created to independently regulate molecular diffusion and substrate-catalyst interactions.
• Electrocatalytic performance was evaluated using techniques including kinetic analysis, impedance spectroscopy, adsorption measurements, in situ spectroscopy, and density functional theory (DFT) calculations.

Main Results:

• Ligand intercalation successfully created tunable nanochannels, independently controlling mass transport and substrate-catalyst interactions.
• Expanded interlayer spacing enhanced alcohol oxidation by improving mass transport and active-site accessibility.
• π-electron-rich ligands promoted aldehyde oxidation via strengthened π-π interactions and accelerated hydrogen atom transfer (HAT), shifting the rate-determining step.
• Optimized MOFs achieved low onset potentials, high current densities (up to 200 mA cm⁻²), and near-quantitative Faradaic efficiencies for biomass substrates like 5-hydroxymethylfurfural and 2,5-diformylfuran.

Conclusions:

• Ligand-intercalated MOFs provide a versatile platform for precise microenvironment control in electrocatalysis.
• This strategy enables selective reaction-pathway engineering, decoupling key factors influencing catalytic performance.
• The approach significantly advances electrocatalytic biomass valorization, offering efficient and selective conversion of biomass-derived molecules.