Single-atom Ni-N4 sites coordinate dual nonradical oxidation pathways via peroxymonosulfate activation: Computational insights and in situ spectroscopic analyses
Qingming Zeng, Qingming Zeng, Yanjun Wen, Xiaoguang Duan, Xing Xu, Jing Tan, Qingyan Zhang, Yilin Liu, Qingyi Zeng, Qingyi Zeng
Abstract
In this work, we revealed a dual-pathway nonradical oxidation (NRO) system catalyzed by Ni single atom catalyst (NiN4) accommodated in the carbon nitride substrate. The monatomic Ni coordinated with four N atoms (Ni-N4) is determined as the dynamic catalytic center for peroxymonosulfate (PMS) activation, showing an exceptional specific rate constant of 3.34 min-1 g-2 L-2 (29.7 times that of CN/PMS system) in oxidizing bisphenol A and other refractory organics. In situ Raman, X-ray absorption, and electrochemical analyses as well as theoretical simulations demonstrate that the Ni-N4 sites exhibit strong interaction with PMS benefited from the modulated electronic structures, resulting in nonradical surface-bonding active complexes (NiN4-PMS*) and deuterogenic high-valent Ni(IV)-Oxo species. The dual-pathway NRO process will spontaneously coordinate both electron transfer process via CN matrix and direct electron transfer by Ni(IV)-Oxo for selective organic oxidation with excellent anti-interference ability and adaptability.