Palladium-hydrogen system calculated from first principles

Abstract In the experiment, it has been observed that the resistivity of palladium (Pd) is sensitively reduced by the absorption of hydrogen, and the detection of hydrogen has been achieved by this principle. However, the realization of the detection only relies on the calibration of the resistivity and the hydrogen concentration of the specific detection model and lacks theoretical analysis. Based on the Density functional theory calculations, the structural, thermodynamic and electronic properties and conductivity of hydrogen atoms adsorbed on the Pd (111) surface at different concentrations were studied in a rare hydrogen environment (1%). The calculation results show that the adsorption mode of hydrogen atoms on the fcc site is the most stable. The differential charge density analysis shows that the interaction between hydrogen atoms and the metal surface increases with the increase of the number of hydrogen atoms, which can be confirmed by the calculation of the electron locality function (ELF) of the system. The DOS analysis shows that the electron number density near the Fermi level of the Pd-H system is 0.521% 0.403% and 0.333% lower than that of the Pd layer respectively. We find that the electron number density near the Fermi level determines the conductance change of the Pd-H system under rare hydrogen conditions.