Single crystalline CeO 2 nanotubes
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Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059, China 3 Key Laboratory of Special Functional and Smart Polymer Materials of Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi’an 710072, China 2
© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 5 August 2020 / Revised: 7 September 2020 / Accepted: 8 September 2020
ABSTRACT Here, we report a facile synthetic methodology to prepare uniform single crystalline CeO2 nanotubes through a hydrothermal transformation of CeO2 nanorods in aqueous Ce(NO3)3 solution. A chemically driven etching-dissolution-deposition mechanism is proposed, involving the surface Ce3+ hydrolysis and dissolution at tips of nanorods and subsequent redeposition and crystallization on the outer sides of nanorods. Compared to CeO2 nanorods, CeO2 nanotubes exhibited the richer structural defects, higher reducibility and larger surface area, leading to a higher haloperoxidase-like activity.
KEYWORDS CeO2 nanorod, hydrothemal transformation, CeO2 nanotube, etching-dissolution-deposition mechanism, haloperoxidase-like activity
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Introduction
CeO2, one of the most abundant rare earth oxides, shows tremendous potential applications in the fields of catalysis, fuel cells, biomedicines and others due to its unique reversible redox pair of Ce3+/Ce4+ under ambient conditions [1]. Their performances are significantly determined by the physicochemical properties of CeO2 including morphologies, surface areas, exposed crystal planes, abundance of structural defects, etc. [2, 3]. Therefore, many efforts have been devoted to the design and synthesis of CeO2 nanomaterials with the tailored physicochemical surfaces as well as various morphologies including rods, spheres, octahedras, cubes and sheets [4–9]. Among various shaped CeO2 structures, CeO2 nanotubes (NT-CeO2) are generally prepared by electrochemical deposition in anodie aluminum oxide (AAO) film or template methods (Ce(OH)3, Ce(OH)CO3, etc.) [10–15]. Practically, the polycrystalline NT-CeO2 were produced [10–13, 16]. In contrast, synthesis of single crystalline NT-CeO2 is still challenging due to the lack of layered features of CeO2. The precipitation-aging process had been adopted to prepare single crystalline NT-CeO2 in a very low yield accompanied with a large number of nanowires and nanoparticles [16]. Also, the diameter and wall thickness of nanotubes were randomly distributed. NT-CeO2 was also thermally decomposed from Ce(OH)3 nanotubes only under rigorous oxygen-free conditions [14]. Overall, the scalable and facile synthesis of single crystalline NT-CeO2 has not been achieved. Herein, we report a facile preparation of uniform single crystalline NT-CeO2 with high yield through a chemically driven etching-dissolution-deposition method between presynthesized CeO2 nanorods (NR-CeO2) and C
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