One-step calcined cellulose-derived NiNx nanoclusters catalyst: Unleashing non-radical peroxymonosulfate activation...

Carbon-based catalysts doped with transition metals effectively activate persulfate for the advanced oxidation of endocrine disruptors in water. However, research on nickel-doped catalysts is limited, especially regarding non-radical mechanisms, and typically focuses on synthetic organic compounds rather than natural cellulose. This study used wheat straw cellulose to synthesize NiNx nanocluster catalysts (Ni-NC) via a one-step calcination method. The Ni-NC/peroxymonosulfate system significantly enhanced the mass transfer between the catalyst, PMS, and contaminants, resulting in a 95.8 % removal efficiency of p-nitrophenol (PNP) within 30 min. Experimental results showed that non-radical pathways, particularly involving singlet oxygen and electron transfer, were key to PNP degradation. This study emphasizes the crucial role of nickel atomic sites in PNP removal through electron transfer processes between Ni(II) and Ni(III). It further confirms the formation of Ni-O bonds, indicating the presence of high-valent metal‑oxygen species. Fukui function analysis and high-performance liquid chromatography-mass spectrometry identified three PNP elimination pathways with minimal toxicity intermediates, as predicted by the Toxicity Estimation Software Tool. These results enhance the effective synthesis of nickel-doped biocatalysts sourced from natural cellulose and establish a theoretical framework for controlling non-radical pathways in water treatment processes.