CeO2 enhancement on in-situ grown Ni3S2 on nickel foam for 5-hydroxymethylfurfural electrooxidation

Electrooxidation of 5-hydroxymethylfurfural (HMF) has long been recognized to efficiently produce the bioplastic precursor, 2,5-furandicarboxylic acid (FDCA). Introducing composite components to construct multiphase interfaces has high potential in modulating the electronic structure of catalysts. Therefore, we synthesized Ni 3 S 2 -CeO 2 /NF using a three-dimensional porous foam nickel scaffold, in-situ grown Ni 3 S 2 /NF via hydrothermal sulfidation, and further incorporated CeO 2 . Characterization with XRD, HRTEM, and SAED confirms the phases of Ni 3 S 2 and CeO 2 and their heterojunctions. XPS analysis shows that CeO 2 increases the Ni 3+ /Ni 2+ ratio; in situ Raman spectroscopy confirms that NiOOH (Ni 3+ ) regenerated from Ni 3 S 2 /Ni(OH) 2 (Ni 2+ ) is the active material for HMF oxidation, complementarily demonstrating that CeO 2 facilitates NiOOH production and that the oxidation process follows an indirect mechanism. Electrochemical analysis shows that at 1.504 V (vs. RHE), Ni 3 S 2 -CeO 2 /NF achieves 99.5% conversion (vs. 83.1%) of 30 mL of 10 mM HMF within 120 minutes, with 99.4% (vs. 89.2%) FDCA selectivity at 97.1% (vs. 78.4%) Faraday efficiency, along with excellent stability, compared to Ni 3 S 2 /NF. DFT calculations indicate that the synergistic effect of CeO 2 enhances HMF adsorption on NiOOH and significantly reduces the activation energies of all associated elementary reactions. This study provides thorough analysis into how Ni 3 S 2 -CeO 2 /NF has enhanced HMF oxidation capabilities.