Integrating the confinement effect and bimetallic cycles in a hierarchical Co3O4@Co3O4/Fe3O4 yolk-shell nanoreactor for peroxymonosulfate activation enhancement
Bo Li, Huanyan Xu, Gu-Hao-Nan Chi, Limin Dong, Lianwei Shan, Liguo Jin, Yanli Zhuang, Mao-Chang Cao, Xiulan He, Shuyan Qi
Abstract
It is still a challenging task to reasonably design an efficient Co 3 O 4 -based nanoreactor for persulfate activation and accurately disclose the confined reaction mechanism. Herein, we design and prepare a hierarchical Co 3 O 4 @Co 3 O 4 /Fe 3 O 4 yolk-shell nanoreactor (CT@CT/MG). In this yolk-shell structured nanoreactor, a Co 3 O 4 solid sphere is the yolk and a flower-like Co 3 O 4 hollow sphere wrapped by Fe 3 O 4 nanoparticles is the shell. The void between them constitutes a confined space. Various instrumental techniques are used to characterize the structure and compositions of this nanoreactor. Degradation experiments show that CT@CT/MG have powerful capability to activate peroxymonosulfate (PMS) for the degradation and mineralization of various organic pollutants and even their mixture. Radical quenching experiments and EPR results confirm that •OH and SO 4 •− are the dominant reactive oxygen species in the CT@CT/MG-PMS system. Electrochemical measurements indicate that CT@CT/MG have better electron transfer ability and lower charge transfer resistance. In-situ characterization techniques including in-situ FT-IR and in-situ Raman are employed for deep insights into the potential reaction mechanisms. XPS analyses prove that Fe 2+ promote the cycling regeneration of the reactive Co 2+ . MD simulations and DFT calculations disclose the confined reaction mechanisms by the means of comparative investigations in a confined space and under the unrestricted environment.