Hydrogen Adsorption on Pd–In Intermetallic Surfaces

It has recently been shown that $$\hbox {CO}_2$$ hydrogenation to methanol over PdIn and $$\hbox {In}_2\hbox {O}_3$$ depends critically on the adsorption energy of hydrogen. Here we use density functional theory calculations to investigate hydrogen adsorption over Pd–In intermetallic compound surfaces with different Pd:In ratios. The electronic structure and properties of hydrogen adsorption are investigated for a range of surface facets and compared to the corresponding results for the pure parent metals and Cu. Increased In content is found to shift the Pd(d) density of states away from the Fermi level, making the intermetallic Pd–In compounds to appear “Cu-like”. We find a linear correlation between the hydrogen binding energy and the d-band center of surface Pd atoms. Understanding of how the hydrogen adsorption energy depends on composition and structure provides a possibility to enhance the performance of $$\hbox {CO}_2$$ hydrogenation catalysts to methanol.