Amorphous Engineering Driving d-Orbital High Spin Configuration for Almost 100% O-Mediated Fenton-Like Reactions.

The inherent atomic disorder in amorphous materials leads to unsaturated atomic sites or dangling bonds, effectively modulating the material's electronic states and rendering it an ideal platform for the growth of single atoms. Herein, the electronic structure of isolated cobalt atoms anchored on amorphous carbon nitride (Co-ACN) is modulated through a substrate amorphization engineering, enabling the thorough removal of pazufloxacin (PZF) in 1 min with a high reaction rate constant (k) of 3.504 min by peroxymonosulfate (PMS) activation. Experiments and theoretical calculations reveal that Co-ACN exhibited a higher coordination environment (Co-N) compared to crystalline Co-CCN (Co-N). Meanwhile, the t energy level enhancement of Co 3d orbital promotes electron transition from t to e, inducing more unpaired electrons and thereby driving the transition from a low-spin state (LS, t e ) to a high-spin state (HS, t e ). The HS Co-ACN optimized the d-band center, boosted the electronic transfer, and weakened the interaction between Co 3d and O 2p orbitals of HSO , thereby enabling nearly 100% selective singlet oxygen (O) generation, whereas Co-CCN yielded coexisting reactive oxygen species (ROS). This work opens up a new paradigm for regulating the electronic structure of single-atom catalysts at the atomic scale.