Efficient Homolytic Cleavage of H 2 O 2 on Hydroxyl-Enriched Spinel CuFe 2 O 4 with Dual Lewis Acid Sites.

Traditional H ₂ O ₂ cleavage mediated by macroscopic electron transfer (MET) not only has low utilization of H ₂ O ₂ , but also sacrifices the stability of catalysts. We present a non-redox hydroxyl-enriched spinel (CuFe ₂ O ₄ ) catalyst with dual Lewis acid sites to realize the homolytic cleavage of H ₂ O ₂ . The results of systematic experiments, in situ characterizations, and theoretical calculations confirm that tetrahedral Cu sites with optimal Lewis acidity and strong electron delocalization can synergistically elongate the O-O bonds (1.47 Å → 1.87 Å) in collaboration with adjacent bridging hydroxyl (another Lewis acid site). As a result, the free energy of H ₂ O ₂ homolytic cleavage is decreased (1.28 eV → 0.98 eV). H ₂ O ₂ can be efficiently split into ⋅OH induced by hydroxyl-enriched CuFe ₂ O ₄ without MET, which greatly improves the catalyst stability and the H ₂ O ₂ utilization (65.2 %, nearly 2 times than traditional catalysts). The system assembled with hydroxyl-enriched CuFe ₂ O ₄ and H ₂ O ₂ affords exceptional performance for organic pollutant elimination. The scale-up experiment using a continuous flow reactor realizes long-term stability (up to 600 mL), confirming the tremendous potential of hydroxyl-enriched CuFe ₂ O ₄ for practical applications.
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