Low-Crystalline Feox on Carboxylic Cnts as Singlet Oxygen Mediated Fenton-Like Catalysts with Dual Reaction Sites

Abstract

A facile method to prepare the ultra-dispersed low-crystalline FeOx (2-5nm) particles anchored on the carboxylic carbon nanotubes (CCNTs) was reported in this paper. The low-crystalline FeOx/CCNTs system features outstanding Fenton-like activity that is 24.3 times larger than that of conventional crystalline Fe2O3 (4-8nm) /CCNTs. It also exhibits good stability, broad pH range and versatility in the catalytic degradation of different types of (cationic and anionic) compounds. Through comprehensive mechanistic investigations, we have ascribed the superior catalytic performance of the low-crystalline FeOx/CCNTs system to a reaction pathway that is distinct from the common Fenton-like reaction path with HO• as the main reactive oxygen species. Specifically, 1O2 was detected as the reactive intermediate by introducing oxygen vacancy and Fe2+ as “Fenton-catalytic” dual reaction center to promote H2O2 decomposition. The carboxylic group on the surface of carbon nanotubes (CNTs) can form Fe-O-C bonds, reducing the redox potential of Fe(III)/Fe(II) and influencing the decomposing of H2O2. Meanwhile, the surface oxygen vacancy in oxide surfaces largely promote the interfacial charge transfer. This work addresses an imaginative leap foward the understanding and design of the metastable iron oxides incorporated in carbon matrix with strong coupling ability.

Keywords: Low-crystalline FeOx, CCNT, Oxygen vacancy, Dual reaction sites