First-principles study on the interfacial activation of peracetic acid over bimetallic 3d-TM@N-CNTs for triclosan degradation

Advanced oxidation technologies based on peracetic acid (PAA) have attracted widespread attention in the field of water pollution treatment. However, the development of highly efficient and stable PAA activation catalysts remains a challenge. This study employed first-principles density functional theory (DFT) calculations to systematically investigate the adsorption and activation properties of PAA by ten types of 3d transition metal-doped nitrogen-doped carbon nanotubes (3d-TM@N-CNTs). Five candidate metals (V, Cr, Mn, Fe, and Co) with moderate adsorption strengths were screened from single-atom catalysts (SACs). Structural optimization revealed that PAA undergoes molecular adsorption on Ni/Cu/Zn@CNTs, but dissociative adsorption on all other SACs and DSCs. Twenty dual-site catalysts (DSCs) were constructed to evaluate the effects of two nitrogen coordination configurations (a: M 1 M 2 –N 6 shared-coordination cage, b: MN 4 /M′N 4 adjacent independent coordination) on PAA adsorption. Bimetallic synergistic effects significantly enhanced PAA adsorption compared to SACs. To examine the product desorption behavior, the ·OH desorption energies were calculated, ranging from −0.56 to 4.60 eV. CrFe(a) (Δ E ads = −4.34 eV, Δ E des = 0.99 eV), MnCo(b) (−4.14 eV, 1.28 eV), and VCo(b) (−4.24 eV, 1.38 eV) were identified as the promising candidates, achieving a balance between PAA activation and product release. Bader charge analysis and difference charge density revealed that the mechanism of bimetallic sites was categorized into concerted activation and main-auxiliary synergy. Co-adsorption calculations confirmed that PAA and TCS can stably coexist on the dual-metal site, with PAA preferentially occupying the active site for activation. This work establishes a catalyst–PAA–ROS–TCS mechanistic link and provides theoretical guidance for the rational design of PAA activation catalysts in water treatment applications.