Adaptive electron transfer in nickel-zinc oxide catalysts for selective generation of surface-stabilized radicals

Efficient advanced oxidation processes are essential for wastewater treatment, yet achieving both high reactivity and selectivity toward targets in complex matrices remains daunting, largely due to inherent trade-offs between radical and nonradical pathways. Surface-bound radicals promise enhanced oxidant utilization and selectivity, but their generation is often hampered by inefficient stabilization by conventional catalysts. Herein, we engineer a yolk-shell NiO/ZnO heterostructure that selectively generates surface-bound radicals via peroxymonosulfate (PMS) activation. The yolk-shell NiO/ZnO delivers exceptional degradation of 4-chlorophenol, achieving oxidant utilization efficiency of 96.9% and a kinetic constant up to 53.2-fold higher than that of single-metal analogs. Spectroscopic characterization and theoretical calculations reveal adaptive electron transfer in Ni-O-Zn, generating high-valent Ni³⁺ species for PMS adsorption and facilitating its spontaneous cleavage into surface-stabilized SO₄^•- and HO• radicals. Spatial confinement within the yolk-shell architecture further enriches reactants. These combined features promote salinity resistance, environmental adaptability, and catalytic stability of the catalytic system. This work provides a strategic design framework for bimetallic catalysts with tunable electronic interfaces to selectively generate reactive species in sustainable wastewater treatment.