Issue 6, 2024

Crystallinity regulation-induced organic degradation on ultra-thin 2D Co3O4/SiO2 nanosheets: the critical trigger of oxygen vacancies

Abstract

As an antibiotic drug, sulfamethoxazole (SMX) is a nitrogen- and sulfur-containing heterocyclic compound as well as an endocrine disruptor that is difficult to biodegrade. Not only can it exist stably in soil and water bodies for a long time, but it also can cause potential harm to the environment and human health. Therefore, it is of great practical significance to adopt effective treatment methods to alleviate the damage of sulfadiazine drugs on microorganisms and accelerate their degradation rate in water. Cobalt-mediated peroxymonosulfate (PMS) activation is considered an effective approach that can generate reactive species for the degradation of pollutants. Herein, a solvent-free intercalation method was developed to obtain ultra-thin hemi-crystalline Co3O4/SiO2 nanosheets, in which crystallinity could be regularly controlled by the calcination atmosphere. Hemi-Co3O4/SiO2 possessed enriched oxygen vacancies (OV), precise peroxymonosulfate (PMS)-binding affinity and rapid Co2+/Co3+ conversion activity, which triggered both radical and nonradical reactions for efficient SMX oxidation. The SMX removal efficiency of hemi-Co3O4/SiO2 (rate constant = 1.101 min−1) was 4.95 times higher than that of the regular cobalt oxide. Radical (˙O2 and SO4˙) and non-radical (1O2) pathways were verified to be key mechanisms in the degradation. It was found beyond expectation that ˙O2 was produced only on amorphous and hemi-crystalline Co3O4, which was nearly absent on highly crystalline Co3O4. This work provides insights into the critical relationship between crystallinity regulation and the activity of advanced oxidation process (AOP) catalysts, clarifies the diverse pathways of the catalysts of different crystallinities, and provides guidance for rational catalyst design for sustainable water decontamination technologies.

Graphical abstract: Crystallinity regulation-induced organic degradation on ultra-thin 2D Co3O4/SiO2 nanosheets: the critical trigger of oxygen vacancies

Supplementary files

Article information

Article type
Paper
Submitted
19 Febr. 2024
Accepted
20 Apr. 2024
First published
22 Apr. 2024

Environ. Sci.: Nano, 2024,11, 2507-2520

Crystallinity regulation-induced organic degradation on ultra-thin 2D Co3O4/SiO2 nanosheets: the critical trigger of oxygen vacancies

W. Bai, H. Lu, Y. Liu, X. Yuan, Y. Ai, L. Wang and Z. Chen, Environ. Sci.: Nano, 2024, 11, 2507 DOI: 10.1039/D4EN00134F

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