Detection of Layer Charge Density in Layered Double Hydroxides and Studies on Host‐Guest Interactions

Abstract The layer charge density of layered double hydroxides (LDHs) significantly affects interlayer spacing, the arrangement of interlayer anions and water molecules, thermal stability, as well as adsorption performance. However, traditional methods for evaluating the layer charge density of LDHs are complex, prone to large errors, and impacted by numerous factors, rendering these methods unable to facilitate direct comparisons of layer charge density across different LDH compositions. Consequently, this study proposes a novel approach based on the host‐guest supramolecular interactions in LDHs to investigate the layer charge density by analyzing changes in the position of the infrared absorption peaks of interlayer guest species. The shifts in infrared absorption peak positions are employed to assess the layer charge density of MgAl‐LDHs with varying molar ratios (M 2+ /M 3+ =2, 2.5, 3, 3.5, 4). The validity of using infrared peak position shifts is corroborated through a combination of techniques, including Raman spectroscopy, TG‐DTG, XRD, Zeta potential, and adsorption analyses. Furthermore, the layer charge density of NiAl, CoAl, MgFe, and NiFe‐LDHs are evaluated, confirming the universality of the infrared method. By ranking layer charge density of LDHs with different compositions and ratios, this study resolves the challenge of comparing LDHs with diverse layer compositions.