Defect-Promoted Ni-Based Layer Double Hydroxides with Enhanced Deprotonation Capability for Efficient Biomass...

Area of Science:

• Electrocatalysis
• Materials Science
• Renewable Energy

Background:

• Nickel-based hydroxides are effective electrocatalysts for biomass oxidation.
• Optimizing active sites is crucial for efficient anodic reactions.
• Understanding deprotonation is key to catalyst performance.

Purpose of the Study:

• To establish a proportional relationship between catalyst deprotonation propensity and 5-hydroxymethylfurfural (5-HMF) oxidation efficiency.
• To engineer ultrathin layer-double hydroxides (UT-LDHs) for enhanced biomass electrooxidation.
• To suppress the oxygen evolution reaction (OER) while promoting value-added chemical production.

Main Methods:

• Density functional theory (DFT) simulations.
• Atomic-scale characterizations including in situ synchrotron diffraction and spectroscopy.
• Tuning metal-oxygen covalency via defect engineering and M3+ co-chemistry in UT-LDHs.

Main Results:

• A direct correlation between deprotonation capability and Faradaic efficiency (FE) for 5-HMF to 2,5-furandicarboxylic acid (FDCA) was identified.
• NiMn UT-LDHs achieved an ultrahigh FE_FDCA of 99% at 1.37 V vs RHE.
• NiMn UT-LDHs maintained high FE_FDCA (92.7%) at 1.52 V, outperforming NiFe UT-LDHs (49.5%).

Conclusions:

• Electronic engineering of deprotonation behavior in metal hydroxides is a universal strategy for modulating competing anodic reactions in biomass electrolysis.
• Ni-O and Mn-O dual active sites in NiMn UT-LDHs facilitate HMF electrooxidation, with Mn-OH deprotonation crucial for selectivity.
• The findings are translatable to various biomass substrates, advancing sustainable chemical production.