Unveiling Multi-Component Synergy in a Multiphase Medium-Entropy Oxide for Efficient 5-Hydroxymethylfurfural Electrooxidation

Abstract The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMFOR) offers a viable route for converting biomass derivatives into high-value chemicals. However, developing non-noble metal electrocatalysts that combine low onset potential, high current density, and long-term stability remains challenging. Herein, multiphase medium-entropy self-supported electrocatalysts NiCoWMoOx/NF, composed of NiO, Co3O4, WO3, and MoO3, was delicated designed and successfully constructed. The NiCoWMoOx/NF achieves an current density of 5 mA cm–2 at 1.23 V (vs RHE) and a maximum current density exceeding 800 mA cm–2. At 1.45 V vs RHE, NiCoWMoOx/NF delivers 98.8% HMF conversion, 97.67% FDCA selectivity, and 96.66% faradaic efficiency, while retaining over 90% of its initial activity after nine consecutive cycles. Combining ex-situ and in-situ characterization techniques, the synergistic roles of each component in the reaction were elucidated: NiO primarily contributes to optimizing the electronic state of Co; WO3 mainly improves the electrical conductivity; and the partial leaching of MoO3 during the electrocatalytic process facilitates the in-situ exposure of more Co active sites. The synergy of these three components enables the efficient conversion of low-valence Co into a highly active and stable CoOOH phase, thereby endowing NiCoWMoOx/NF with superior HMFOR performance. This work provides a referable material and mechanistic strategy for the rational design of high-performance biomass electrocatalysts.