Electrochemical assisted single atom copper modified novel nitrogen doped porous carbon mediated catalytic activity based on D-band center modification: Rapid degradation of enoxacin

Persulfate (PMS) is an excellent free radical initiator with selective degradation of organic pollutants. This article presents the preparation of a high-performance Cu-SA@NCA(Single atom copper modified nitrogen doped aerogel carbon) electrocatalyst with adjustable interfacial separation enhancement effect for the first time. Under the optimal process parameters, the removal rates of ENO, COD, and TOC obtained after 5 min of reaction were 100 %, 73.41 % and 55.15 %, respectively. The average energy consumption was saved by 59.63∼123.25 kWh/kg ENO. After 6 cycles of degrading ENO wastewater, the removal rate of ENO only decreased by 8.55 %. It was demonstrated through characterization such as high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), X-ray absorption near edge structure (XANES), and Fourier Transform Extended X-ray Absorption Fine Spectroscopy (FT-EXAFS) that the single atom copper loaded on the Cu-SA@NCA surface is tightly bound to N in NCA through Cu-N₄ bond bridges, promoting the formation of double electron centers on the catalyst surface. The particle electrode catalyst significantly enhances the PMS activation process over a wide pH range and can accelerate the degradation of enoxacin (ENO). As the reaction center for PMS adsorption and activation, Cu-N₄ has a lower charge transfer resistance and can attract PMS to the catalyst surface, resulting in a higher current response in the PMS system. Organic pollutants release electrons through the carbon matrix of carbon based catalysts and transfer them to Cu-SA@NCA-PMS, promoting PMS activation and the formation of high valence copper ions, enhancing the degradation of pollutants. Density functional theory (DFT) further indicate that the regulatory effect of N on the electron distribution of Cu d orbitals is beneficial for the stretching and cleavage of Cu active centers by PMS, accelerating the process of SO₄⁻· and ·OH generation rate, which is consistent with the results of XANES. In addition, during the degradation process of salt containing organic pollutants in PMS, Cu-SA@NCA exhibits strong resistance to inorganic ions, natural organic matter, and pH value. This work developed a new catalyst that selectively produces SO₄⁻· and ·OH with 97.46 % selectivity, achieving high selectivity and efficiency in degrading pollutants.