Removal of Bisphenol A via peroxymonosulfate activation over graphite carbon nitride supported NiCx nanoclusters catalyst: Synergistic oxidation of high-valent nickel-oxo species and singlet oxygen.

In this work, a g-C 3 N 4 supported NiCx nanoclusters catalyst (NiCx-CN) was developed, and its performance in activating peroxymonosulfate (PMS) was evaluated. Mechanism investigation stated that although singlet oxygen (1O 2) was formed in the catalytic process, its contribution to BPA elimination was weeny. Interestingly, through the experiment with dimethyl sulfoxide as the probe, it was considered that the high-valent nickel-oxo species (Ni&+=O), generated after the interaction of NiCx-CN and PMS, was the dominating reactive oxygen species (ROS). Theoretical calculations (DFT) implied that NiCx-CN might lose electrons to generate high-valent Ni, which was consistent with the detection of Ni3+ on the surface of the used NiCx-CN. Besides, the prepared NiCx-CN showed advantages in resisting the interference of inorganic anions. Meanwhile, three BPA degradation routes had been proposed based on the transformation intermediates. This study will establish a new protocol for PMS activation using heterogeneous Ni-based catalysts to efficiently degrade organic pollutants via a nonradical mechanism. [Display omitted] • A g-C3N4 supported NiCx nanocluster catalyst was prepared by one-step pyrolysis. • The PMSO probe method was extended to the exploration of high-valent Ni&+ =O. • High-valent Ni&+ =O and 1O2 are the main ROS in the NiCx-CN/PMS system. • The formation mechanism of high-valent Ni&+ =O was obtained by DFT calculations. • A reasonable PMS activation mechanism was put forward. [ABSTRACT FROM AUTHOR]