Single-crystalline Fe7S8/Fe3O4 coated zero-valent iron synthesized with vacuum chemical vapor deposition technique: Enhanced reductive, oxidative and photocatalytic activity for water purification

Hongyun Niu; Yongliang Yang; Weijia Zhao; Hongzhou Lv; Hui Zhang; Yaqi Cai

doi:10.1016/j.jhazmat.2020.123442

Single-crystalline Fe₇S₈/Fe₃O₄ coated zero-valent iron synthesized with vacuum chemical vapor deposition technique: Enhanced reductive, oxidative and photocatalytic activity for water purification

J Hazard Mater. 2021 Jan 5:401:123442. doi: 10.1016/j.jhazmat.2020.123442. Epub 2020 Jul 8.

Authors

Hongyun Niu¹, Yongliang Yang², Weijia Zhao², Hongzhou Lv³, Hui Zhang¹, Yaqi Cai⁴

Affiliations

¹ State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
² State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
³ State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Environment, Hohai University, Nanjing, 210098, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
⁴ State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Institute of Environment and Health, Jianghan University, Wuhan, 430056, China. Electronic address: caiyaqi@rcees.ac.cn.

PMID: 32659592
DOI: 10.1016/j.jhazmat.2020.123442

Abstract

Well-defined core/shell type single crystalline Fe₇S₈/Fe₃O₄ coated α-Fe hybrids (Fe₇S₈/Fe₃O₄@Fe) are synthesized with vacuum chemical vapor deposition (CVD) technique. The CVD process triggers conversion of naturally formed Fe₃O₄ layer on the surface of commercial Fe nanoparticles from amorphous into single crystalline phase. The Fe₇S₈/Fe₃O₄ coat promotes the surface affinity of dissolved oxygen and targets and rapidly transfers electrons from the Fe core to targets, which decreases water splitting on Fe₇S₈/Fe₃O₄@Fe surface and endows Fe₇S₈/Fe₃O₄@Fe with ultra-strong reducibility and improved oxidative ability under different conditions. Different with the sulfurized ZVI prepared with hydrothermal or solvothermal method, the increase of reaction solution pH is retarded due to the relieved water splitting instead of releasing H⁺ via oxidation of S^2-/S₂^2- on the Fe₇S₈ coat. The cooperation of Fe₇S₈ with Fe₃O₄ and α-Fe not only improves the anti-oxidation ability of Fe₇S₈ coating but also broadens its band gap. By using Fe₇S₈/Fe₃O₄@Fe nanohybrids as photocatalysts, light irradiation accelerates the degradation of organic pollutants combined with enhanced mineralization efficiency. The Fe₇S₈/Fe₃O₄@Fe exhibits good performance when it is utilized to treat the influent from a municipal sewage treatment plant upon air aeration or under visible light and solar light irradiation.

Keywords: Fe(7)S(8)/Fe(3)O(4)@Fe; Oxidative activity; Photocatalysts; Reductants; Vacuum chemical vapor deposition.

Publication types

Research Support, Non-U.S. Gov't