Band gap energies in selected multi-cation and high-entropy layered double hydroxides

Introduction: Layered double hydroxides (LDHs) are promising compounds whose properties can be tuned through compositional variation, including the preparation of multi-cation and high-entropy materials. In such complex systems, the band gap is a key parameter governing optical absorption, charge transport, and photocatalytic behavior, and its systematic investigation is therefore essential for understanding structure–property relationships. Materials and methods: In this work, the band gap energies of nine multi-cation and high-entropy LDHs samples, determined from diffuse reflectance spectra using the Kubelka–Munk approach, were evaluated. Results: The calculated band gap values indicate that the samples are wide-bandgap semiconductors with no clear monotonic dependence on either the number of cations or their ratios. Conclusions: This preliminary study suggests that, for the specific multi-cation and high-entropy LDHs investigated, cation identity may have a stronger influence on the apparent optical band gap than cation number or ratio.