Phosphorylation of MWCNTs/PPy/PDA-nZVI Catalyst for Boosted Catalytic Performance

Abstract

Nano zero valent iron (nZVI) is widely studied for its efficient removal of recalcitrant organic contaminants. However, it is prone to oxidation and aggregation, and its structurally dense oxide shell seriously prevents mass and electron transport. Herein, a novel phosphorylated multi-wall carbonnanotubes/polypyrrole/polydopamine supported nZVI (P-MWCNTs/PPy/PDA-nZVI) was successfully fabricated. Induced by the circumferential stress from phosphate ions, a unique 2D agaric-like nanoflake morphology with ultrathin thickness (ca. 20nm) and inhibited dense oxide shell was formed. Impressively, the unprecedented modified kinetic rate constants (K-value) of 116.35 and 154.15 μmol·g-1·s-1 towards para-nitrophenol degradation were obtained in batch and continuous-flow reactors, far outperforming other reported catalysts (1-3 orders of magnitude) and non-P-doped MWCNTs/PPy/PDA-nZVI (1.53 and 10.5 folds). Phosphorylation-dependent enhancement in dispersity, conductivity and hydrophilicity rendered the catalyst with abundant active sites, accelerated electron transfer and boosted catalytic efficiency. The present encouraging findings might shed light on new ways to design high-performance nZVI in water decontamination.