Efficient Homolytic Cleavage of HO on Hydroxyl-Enriched Spinel CuFeO with Dual Lewis Acid Sites.

Traditional HO cleavage mediated by macroscopic electron transfer (MET) not only has low utilization of HO, but also sacrifices the stability of catalysts. We present a non-redox hydroxyl-enriched spinel (CuFeO) catalyst with dual Lewis acid sites to realize the homolytic cleavage of HO. 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 HO homolytic cleavage is decreased (1.28 eV → 0.98 eV). HO can be efficiently split into ⋅OH induced by hydroxyl-enriched CuFeO without MET, which greatly improves the catalyst stability and the HO utilization (65.2 %, nearly 2 times than traditional catalysts). The system assembled with hydroxyl-enriched CuFeO and HO 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 CuFeO for practical applications.