Improving the reduction and sensing capability of Fe3O4 towards 4-nitrophenol by coupling with ZnO/Fe0/Fe3C/graphitic carbon using ZnFe-LDH@carbon as a template. (1st December 2021)

• Record Type: Journal Article
• Authors: Baye, Anteneh F.; Han, Dong-Ho; Kassahun, Shimelis K.; Appiah-Ntiamoah, Richard; Kim, Hern
• Is Part Of: Electrochimica acta. Volume 398(2021)
• Publication Date: 2021-12-01
• Subjects: ZnFe-LDH -- Carbothermal reduction -- Heterostructure -- Synergy -- 4-NP electroanalysis; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2021.139343
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: Carbothermic reduction of ZnFe-LDH@C to Fe3 O4 /ZnO/Fe 0 /Fe3 C/g-C heterostructure. Each component plays a unique role that works in synergy to boost 4-NP detection. Zinc and carbon maintain the composite microstructure for fast ion diffusion. Fe 0 enhances 4-NP adsorption, Fe3 C boosts conductivity and Fe3 O4 /ZnO reduces 4-NP. Fe3 O4 /ZnO/Fe 0 /Fe3 C/g-C exhibits high sensitivity with a LOD of 3.6 nM. Abstract: FeOx-carbon composites are highly active for biomolecule electroanalysis; but not for environmental pollutants such as 4-nitrophenol (4-NP). This is due to the weak electroreduction capability of FeOx towards 4-NP. Herein, we demonstrate that by hybridizing Fe3 O4 with ZnO/Fe 0 /Fe3 C/graphitic carbon (g-C) this limitation is mitigated leading to exceptional 4-NP reduction and detection. The Fe3 O4 /ZnO/Fe 0 /Fe3 C/g-C heterostructure is synthesized via carbothermal reduction of ZnFe-LDH@carbon under N2 . The effect of temperature, LDH composition, and g-C on the microstructure and chemical composition of the heterostructure are thoroughly investigated. The presence of ZnO and g-C induce structural pores within Fe3 O4 /ZnO/Fe 0 /Fe3 C/g-C by preventing the aggregation of Fe3 O4 particles which leads to high ECSA and mass transfer. Meanwhile, a temperature > 800 °C is crucial to avoid the inactive ZnFe2 O4 phase and transform ZnFe-LDH@carbon fully into Fe3 O4 /ZnO/Fe 0 /Fe3 C/g-C.The Fe 0 site facilitates 4-NP adsorption, while Fe3 C acts as a conductive channel for fast electron transfer at Fe 2+ /Fe 3+ redox couple sites in Fe3 O4 where 4-NP electroreduction occurs. These properties work in synergy leading to high sensitivity, ultra-low 4-NP detection limit, and selectivity in PBS as well as tap and river water. The results of this study show that the electroanalytical performance of Fe3 O4 for environmental pollutants can be tuned by coupling it with the appropriate interface(s). Graphical abstract: Fe3 O4 /ZnO/Fe 0 /Fe3 C/g-C heterostructure provides high 4-NP adsorption capacity, fast electron transfer rate, and redox couple active sites to boost 4-NP electroreduction Image, graphical abstract .