N-doped 2D graphite-2H nanoplatelets (GNPs) with enhanced PMS activation performance: Structure-dependent performance and Catalytic Mechanism

The N-doped two-dimensional (2D) carbon-based catalysts play a crucial role in the PMS catalytic activity of advanced oxidation processes (AOPs). However, their activation mechanism still lacks a reasonable explanation. A low-cost and one-step synthesis of N-doped graphite-2H nanoplatelets (N-GNPs) were prepared through the calcination under 600°C. N-GNPs 0.5 -600 was applied to activate permonosulfate (PMS) 19.4 times faster than that of pure PMS system under visible light to degrade bis(monochloro-s-triazine) reactive dye. We first demonstrate that electron arrangement in N-GNPs samples can effectively activate PMS and generate 1 O 2 as much as S O 4 · − and  HO · as the main reactive species. The EPR test results were consistent with the quenching test. Density functional theory (DFT) calculations showed the graphite N adjacent C atoms (Eb= -8.9 eV) were promoted to produce more active sites. Bidirectional regulation of graphite N bonded C atoms form a local electron state, making the C most active electron donation. The 2P Z orbital of carbon atoms becomes occupied with the free electrons. The localized orbitals lead to the stronger Columbic repulsion of π electrons and enlarged interlayer distance, making it easier for the electrons to give out and accelerate the free-radical process.