<p>The catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid is a key step in the production of bio-based plastics but remains limited by sluggish multi-electron transfer kinetics across multiple reaction intermediates. In this study, we address this long-standing challenge by introducing a Mn-O-Co electron bridge within spinel CoMn<sub>2</sub>O<sub>4</sub> to mediate and accelerate electron transfer. Through precise valence state regulation, we engineer a heterogeneous electron bridge dominated by Mn<sup>4+</sup>-O<sup>2-</sup>-Co<sup>3+</sup> linkages, enabling more efficient electron flow. Experimental characterization and theoretical calculations reveal that the incorporation of Mn<sup>4+</sup> significantly enhances electron delocalization across the bridge. The empty <i>e</i><sub>g</sub> orbitals of Mn<sup>4+</sup> (<i>t</i><sub>2g</sub><sup>3</sup><i>e</i><sub>g</sub><sup>0</sup>) serve as efficient electron acceptors, creating an energy-level gradient with Co<sup>3+</sup> (<i>t</i><sub>2g</sub><sup>4</sup><i>e</i><sub>g</sub><sup>2</sup>) that favors directional electron transfer. Simultaneously, Mn<sup>4+</sup> strengthens metal-oxygen covalency, further improving electron mobility. This engineered electron bridge structure enables highly efficient cooperation across the full six-electron transfer pathway in 5-hydroxymethylfurfural oxidation, driven by a dynamic electron compensation mechanism. As a result, an 2,5-furandicarboxylic acid yield of 98.1% is achieved. This work offers a valuable theoretical foundation for understanding cooperative electron transfer in heterogeneous catalysis and provides a rational strategy for designing efficient electron bridge structures.</p>

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Valence-tuned electron bridge enables high-yield multi-electron HMF oxidation over spinel catalysts

  • Zhong-Ting Hu,
  • Gan He,
  • Xiaohuan Tao,
  • Jinshu Tian,
  • Mingwu Tan,
  • Ni Ouyang,
  • Jun-Long Li,
  • Mian Hu,
  • Jie-Xin Wang,
  • Yihan Zhu,
  • Dapeng Cao,
  • Zhiyan Pan,
  • Yong Wang,
  • Xiaonian Li

摘要

The catalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid is a key step in the production of bio-based plastics but remains limited by sluggish multi-electron transfer kinetics across multiple reaction intermediates. In this study, we address this long-standing challenge by introducing a Mn-O-Co electron bridge within spinel CoMn2O4 to mediate and accelerate electron transfer. Through precise valence state regulation, we engineer a heterogeneous electron bridge dominated by Mn4+-O2--Co3+ linkages, enabling more efficient electron flow. Experimental characterization and theoretical calculations reveal that the incorporation of Mn4+ significantly enhances electron delocalization across the bridge. The empty eg orbitals of Mn4+ (t2g3eg0) serve as efficient electron acceptors, creating an energy-level gradient with Co3+ (t2g4eg2) that favors directional electron transfer. Simultaneously, Mn4+ strengthens metal-oxygen covalency, further improving electron mobility. This engineered electron bridge structure enables highly efficient cooperation across the full six-electron transfer pathway in 5-hydroxymethylfurfural oxidation, driven by a dynamic electron compensation mechanism. As a result, an 2,5-furandicarboxylic acid yield of 98.1% is achieved. This work offers a valuable theoretical foundation for understanding cooperative electron transfer in heterogeneous catalysis and provides a rational strategy for designing efficient electron bridge structures.