Ab initio calculations of the structural, electronic and mechanical properties of palygorskite under high pressure

To further expand the applications of palygorskite (Pal) in materials science, this research employs density functional theory (DFT) to systematically investigate the alterations of its structural, electronic and mechanical properties under high pressure. This finding reveal that the MgO bonds, particularly those associated with ring oxygen atoms, undergo significant contraction under high pressure, which is indicative of the high compressibility of Pal. Meanwhile, the volume of Pal decreases substantially within the pressure interval of 10–20 GPa. Moreover, at 20 GPa, the band gap of Pal diminishes from 4.58 eV at ambient pressure to 4.39 eV, resulting in an increase in conductivity. Subsequent density of states (DOS) analysis corroborates that the reduction in Pal's band gap is predominantly ascribed to the increased contribution of Si 3 s orbitals at 20 GPa. Additionally, the examination of elastic constants reveals a substantial augmentation in shear rigidity along the a-c and b-c planes, which further facilitates the narrowing of the band gap. The Gibbs free energy of adsorbed hydrogen (ΔG_H⁎) DFT calculation results further confirm that the bandgap-narrowed Pal at 20 GPa displays enhanced catalytic performance for hydrogen evolution. Notably, despite significant structural reconfigurations under high pressure, Pal maintains negative binding energies and shows no phase transition, demonstrating exceptional structural stability. This study offers theoretical insights and guidance for optimizing the performance of Pal in a plethora of sophisticated technological applications.