HNTs@CeO2-Au@Co3O4 catalyst for catalytic reduction of 4-nitrophenol and dye pollutants.

This paper reported the preparation of HNTs@CeO2-Au@Co3O4 core-shell hollow tubular composite catalyst for the reductive degradation of aqueous p-nitrophenol (4-NP) and dye (MB, MO) pollutants. The microstructure and physicochemical properties of the catalyst were characterized by the means of TEM, SEM, EDS, XRD, N2 adsorption-desorption, XPS, etc. The results showed that CeO2 and Co3O4 were used as internal and external active layers to well disperse and immobilize Au nanoparticles (NPs), which were constructed upon halloysite nanotubes (HNTs) via interfacial reaction. The formed core-shell composite catalyst (HNTs@CeO2-Au@Co3O4) was based on the HNTs carrier encapsulated by the CeO2/Co3O4 laminated structure with Au NPs. The catalyst can reduce over 96% of 4-NP, MB and MO pollutants within 3.5, 8 and 3min respectively, in which the corresponding first-order kinetic rate constant (0.856, 0.370, 1.337min-1) and turnover frequency (10.99, 1.90, 2.80min-1) were significantly superior to the control materials including HNTs-Au@Co3O4, HNTs@CeO2-Au and HNTs@CeO2@Co3O4. Besides, HNTs@CeO2-Au@Co3O4 catalyst maintained high reduction conversion of 4-NP, MB and MO pollutants and good structural integrity after 6 consecutive uses. The unique CeO2/Co3O4 laminated structural feature and synergistic enhancement effect of composite components effectively promoted the construction of the high-performance catalytic system, greatly improved the catalytic activity and stability of Au NPs, which endowed the HNTs@CeO2-Au@Co3O4 catalyst with remarkable catalytic capability and recycling performance. © 2024 Chinese Society for Environmental Sciences. All rights reserved.