Issue 3, 2021

Engineering of 3D NaxCoO2 nanostructures for enhanced capacitive deionization: performance and mechanism

Abstract

Layered NaxCoO2 (NCO) has been demonstrated as a promising candidate for highly efficient capacitive deionization (CDI). To further improve the desalination performance of NCO, we have developed a facile method to prepare polygon-like 3D NaCoO2 and Na0.6CoO2 nanostructures employing ZIF-67 as a template for enhanced CDI. On the basis of electrochemical measurements, the 3D Na0.6CoO2 electrode shows a higher specific capacitance and conductivity than 3D NaCoO2, implying better CDI performance. As a result, the salt removal capacity of 3D Na0.6CoO2 is 64.48 mg g−1 in NaCl solution with an initial conductivity of 2000 μS cm−1 and cell voltage of 1.2 V. Moreover, the desalination mechanism of 3D Na0.6CoO2 electrode is proposed by taking cyclic voltammetry measurements and ex situ X-ray diffraction into account, realizing the transformation from Na-rich to Na-lean during the desalination. Besides, benefiting from the novel 3D architecture, the long cyclic desalination performance of 3D Na0.6CoO2 electrode is much superior to that of 2D NCO. Thus, this work highlights the significance of the 3D spatial structure on the CDI performance enabled by sodium layered oxides.

Graphical abstract: Engineering of 3D NaxCoO2 nanostructures for enhanced capacitive deionization: performance and mechanism

Supplementary files

Article information

Article type
Paper
Submitted
04 Nov 2020
Accepted
19 Jan 2021
First published
22 Jan 2021

Environ. Sci.: Nano, 2021,8, 657-665

Engineering of 3D NaxCoO2 nanostructures for enhanced capacitive deionization: performance and mechanism

W. Si, Z. Liu, Z. Zhang, W. Ji and H. Li, Environ. Sci.: Nano, 2021, 8, 657 DOI: 10.1039/D0EN01091J

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