Regulating\nthe Electronic Structure of Ni Sites in\nNi(OH)₂ by Ce Doping and Cu(OH)₂ Coupling to\nBoost 5‑Hydroxymethylfurfural Oxidation Performance

Abstract

Biomass\nis a sustainable and renewable resource that can be converted\ninto valuable chemicals, reducing the demand for fossil energy. 5-Hydroxymethylfurfural\n(HMF), as an important biomass platform molecule, can be converted\nto high-value-added 2,5-furandicarboxylic acid (FDCA) <i>via</i> a green and renewable electrocatalytic oxidation route under mild\nreaction conditions, but efficient electrocatalysts are still lacking.\nHerein, we rationally fabricate a novel self-supported electrocatalyst\nof core–shell-structured copper hydroxide nanowires@cerium-doped\nnickel hydroxide nanosheets composite nanowires on a copper mesh (CuH_NWs@Ce:NiH_NSs/Cu)\nfor electrocatalytically oxidizing HMF to FDCA. The integrated configuration\nof composite nanowires with rich interstitial spaces between them\nfacilitates fast mass/electron transfer, improved conductivity, and\ncomplete exposure of active sites. The doping of Ce ions in nickel\nhydroxide nanosheets (NiH_NSs) and the coupling of copper hydroxide\nnanowires (CuH_NWs) regulate the electronic structure of the Ni active\nsites and optimize the adsorption strength of the active sites to\nthe reactant, meanwhile promoting the generation of strong oxidation\nagents of Ni³⁺ species, thereby resulting in improved electrocatalytic\nactivity. Consequently, the optimal CuH_NWs@Ce:NiH_NSs/Cu electrocatalyst\nis able to achieve a HMF conversion of 98.5% with a FDCA yield of\n97.9% and a Faradaic efficiency of 98.0% at a low constant potential\nof 1.45 V versus reversible hydrogen electrode. Meanwhile, no activity\nattenuation can be found after 15 successive cycling tests. Such electrocatalytic\nperformance suppresses most of the reported Cu-based and Ni-based\nelectrocatalysts. This work highlights the importance of structure\nand doping engineering strategies for the rational fabrication of\nhigh-performance electrocatalysts for biomass upgrading.