Nitrogen vacancies regulated the local electron density of iron sites in g-C3N4 to boost the generation of high-valent iron-oxo species in a peracetic acid-based Fenton-like process

Abstract

Large-scale production of high-valent iron-oxo species (Fe(V)=O) for the efficient removal of organic pollutants has been a challenge due to the high activation energy barrier of the Fe(III)-oxidant complex. Here, we propose a novel heterogeneous system using Fe(III)-doped g-C3N4 with three-coordinate nitrogen vacancies (FNCN) as a catalyst for the activation of peracetic acid (PAA). Our investigations and calculations indicate that Fe(III) is the primary active site, and illustrate a nonradical mechanism of two-electron transfer mechanism to produce Fe(V)=O species. Meanwhile, the abundant nitrogen vacancies (Nvs) strengthen the electron distribution of the Fe(Ⅲ) sites to promote reactivity, and reduce the energy barrier to break the O−O bond of PAA in the Fe(Ⅲ)−PAA complex, to achieve the rapid accumulation of Fe(V)=O species. As a result, this heterogeneous system has excellent selectivity and anti-interference in removal of pollutants. Our work offers a unique viewpoint to strengthen a nonradical pathway in PAA activation.