Understanding Li-Al-CO3 layered double hydroxides. (II) Interface electrochemical properties

Miao Yu; Na Du; Haiping Li; Wanguo Hou

doi:10.1016/j.jcis.2019.03.100

Understanding Li-Al-CO₃ layered double hydroxides. (II) Interface electrochemical properties

J Colloid Interface Sci. 2019 Jul 1:547:217-223. doi: 10.1016/j.jcis.2019.03.100. Epub 2019 Mar 30.

Authors

Miao Yu¹, Na Du¹, Haiping Li², Wanguo Hou³

Affiliations

¹ Key Laboratory for Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100, PR China.
² National Engineering Research Center for Colloidal Materials, Shandong University, Jinan 250100, PR China.
³ Key Laboratory for Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100, PR China; National Engineering Research Center for Colloidal Materials, Shandong University, Jinan 250100, PR China. Electronic address: wghou@sdu.edu.cn.

PMID: 30954765
DOI: 10.1016/j.jcis.2019.03.100

Abstract

In the current work, the interface electrochemical (IEC) properties of Li-Al-CO₃ layered double hydroxides (LDHs) with structural positive charges were investigated by experiments and model fitting. The surface charge densities of the LDHs at different electrolyte (NaNO₃) concentrations and pH were determined using acid-base titration. The effective structural charge density and the point of zero net charge are obtained to be ∼5.27 × 10^-3 C/m² and 9.22, respectively. On the basis of the general surface-charging (1-pK and 2-pK) models, the intrinsic surface reaction equilibrium constants pK, pK_a1^int, and pK_a2^int are obtained to be -8.50, 7.49, and 9.51, respectively. The general 2-pK model is combined with the diffuse layer model (DLM, an electrostatic model) to fit the surface-charging data. Model predictions are in good agreement with the experimental data, indicating that the general surface-charging models are reasonable and that the surface-charging behavior of Li-Al-CO₃ LDHs can be described using the 2-pK/DLM model. To the best of our knowledge, this is the first report on the IEC properties of Li-Al LDHs, providing a better understanding for the features of Li-Al LDHs.

Keywords: Acid-base titration; Interface electrochemistry; Layered double hydroxides; Points of zero charge; Surface-charging model.