Anionic regulation Fe/NiOOH electrocatalysts to boost electrooxidation performance of biomass derived...

Nickel-based catalysts show great potential as promising candidates for the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF). However, the limited adsorption capacity of nickel-based catalysts for OH^- and HMF limits their further development. In this study, amorphous Fe/NiOOH-SO_x was generated from nanosheets (Fe/NiOOH-Ni₃S₂), which was pre-fabricated on nickel foam via pre-reconstruction and anionic regulation strategy. The optimized catalyst Fe/NiOOH-Ni₃S₂ demonstrated exceptional activity in the HMF oxidation reaction (HMFOR) with a current density of 10 mA cm^-2 at 1.32 V vs RHE, accompanying with the 98.9 % HMF conversion, 97.8 % 2,5-Furandicarboxylic acid (FDCA) selectivity, 96.8 % Faraday efficiency, and stability for ten cycles. The incorporating amorphous FeOOH reduces the electron density around Ni, promoting the formation of high-valent Ni spices. Meanwhile, the SO_x combined with amorphous hydroxy nickel oxide provides unsaturated sites, which enhances the adsorption capacity of HMF. Density functional theory (DFT) computations reveal that the designed amorphous Fe/NiOOH and surface-adsorbed SO_x collectively modulate the electronic structure of the catalyst, causing an upwards shift of the NiOOH d-band center and enhancing adsorption capacities for both HMF and OH^-. This study proposes the adsorption enhancement mechanism of regulating electronic structure and offers a rational strategy for HMFOR electrocatalysts.