Catalytic Oxygen Activation over the Defective CuO Nanoparticles for Ultrafast Dehalogenation.

The nucleophilic superoxide radical (O 2 •- )-based dehalogenation reaction shows great potential to degrade the toxic halogenated organic compounds (HOCs). But such an O 2 •- -mediated reductive reaction often suffers from the competition of the secondary oxidative species (e.g., •OH), leading to inferior electron efficiency and possible disinfection byproduct formation. Here, an O 2 •- -dominant ultrafast dehalogenation system is developed via molecular O 2 activation by the oxygen vacancy (OV)-rich CuO nanoparticles (nCuO). The nCuO delivers a remarkable dechlorination rate constant of 3.92 × 10 -2 L min -1 m -2 for 2,4-dichlorophenol, much higher than that of the conventional zerovalent (bi)metals. The absorbed O 2 on the nCuO surface is exclusively responsible for O 2 •- generation, and its reactivity increases with the elevated OV content because of the enhanced orbital hybridization between the O p- and Cu d-orbitals. More importantly, the ubiquitous carbonate species firmly bound to the surface OVs block the formation of the secondary oxidative species via H 2 O 2 activation, assuring the dominant role of the in situ generated O 2 •- for the selective HOC dehalogenation. The carbonate-deactivated OVs of the nCuO can be feasibly recovered via air annealing for sustainable dehalogenation. This work provides a new opportunity for selective O 2 •- generation via interfacial defect engineering for dehalogenation and other environmental applications.