Optimizing Surface <sup>*</sup> H Coverage over Cu <sub>2</sub> O/Co <sub>3</sub> O <sub>4</sub> Heterojunction Enables Efficient Neutral Electrocatalytic Hydrogenation of 5‐hydroxymethylfurfural to 2,5‐dihydroxymethylfuran
Yun Ge, Wei Wang, Xiaoqiang Pan, Jia‐Wei Huang, Jie‐Jie Chen, Wu‐Jun Liu, Yuqin Zou, Han‐Qing Yu
Abstract
Abstract Electrochemical hydrogenation (ECH) of biomass‐derived 5‐hydroxymethylfurfural (HMF) to 2,5‐dihydroxymethylfuran (DHMF) offers a sustainable route for biomass valorization. Recent studies have underscored the importance of reactive hydrogen species ( * H) on the catalyst surface in determining reaction selectivity, particularly under neutral conditions. However, the mechanistic understanding of how * H coverage governs the reaction pathway remains poorly understood, and effective strategies for optimizing surface * H coverage are still lacking. Herein, density functional theory (DFT) calculations first reveal that an optimum * H coverage on the Cu 2 O surface effectively suppresses ketyl intermediate coupling and thermodynamically favors DHMF formation. Inspired by this insight, a Cu 2 O/Co 3 O 4 heterojunction catalyst is constructed, in which Co 3 O 4 serves as a redox‐active cocatalyst to stabilize Cu⁺ sites and modulate the electronic structure of Cu 2 O, thereby enhancing H 2 O activation and enabling precise tuning of * H coverage. The Cu 2 O/Co 3 O 4 heterojunction catalyst delivers an excellent HMF conversion (97%) and DHMF selectivity (97%), significantly outperforming the pristine Cu 2 O (71% DHMF selectivity, 62% HMF conversion). This work uncovers the mechanistic role of * H coverage in pathway regulation and highlights heterointerface engineering as a powerful strategy for designing efficient electrocatalysts for selective biomass upgrading under neutral conditions.