Synergistic effects between cationic defects and Ce-doping in NiAl-LDHs for efficient HMF electrooxidation

The valorization of 5-hydroxymethylfurfural (HMF) offers a sustainable pathway to address escalating global energy demands, making the design of efficient electrocatalysts for HMF oxidation reaction (HMFOR) a critical research priority. In this study, we synergistically integrated cationic defect engineering and Ce doping to optimize layered double hydroxides (i.e., NiAl-LDHs) for efficient HMFOR. The experimental results show that the coexistence of Ce species and cationic defects synergistically modulates the electronic structure of Ni species, maximizing the exposure of active Ni sites while enhancing electrical conductivity. Furthermore, the introduction of Al 3+ vacancies and Ce 3+ /Ce 4+ redox pairs promotes the formation of high-valent Ni 3+ active species. This dual modification strategy significantly enhances HMFOR performance, with NiAlCe(3%)-LDH-E achieving benchmark metrics at 1.45 V RHE :100% HMF conversion, nearly 100% 2,5-furandicarboxylic acid yield, and nearly 99% Faradaic efficiency. Density functional theory (DFT) calculations validate that cationic defects and Ce doping cooperatively optimize HMF adsorption at active surface centers and reduce the energy barrier for the rate-determining *HMF dehydrogenation to *HMF-to-5-hydroxymethyl-2-furancarboxylic acid (*HMFCA) step, providing atomic-level insights into the enhanced catalytic mechanism.