SAIP2025

H2O adsorption on PtSb2(100) surface

Not scheduled

2h 50m

Solomon Mahlangu House (University of the Witwatersrand, Johannesburg)

Poster Presentation Track A - Physics of Condensed Matter and Materials Poster Session

Speaker

Samuel Mangwejane (University of Limpopo)

Description

We performed water adsorptions on the PtSb2 (100) surface, where H2O was adsorbed through oxygen on top of the surface Pt and Sb atoms. The (100) surface was explored by increasing the number of H2O on the surface. The (100) surface was explored by increasing the number of H2O on the surface. Lastly, the full-surface coverage (16/16 H2O/Sb, Pt) was investigated where all Pt and Sb were adsorbed with H2O. We observed that the H2O molecules assemble at an angle on the surface and lie horizontal in particular for multi adsorptions. we found that in all cases the water molecule/s gave larger bond length between Pt/Sb and water O atoms (Pt–OH2 and Sb–OH2). As such, it indicated no bond formation between the surface and water molecules. The H2O bond angle was slightly larger than the isolated H2O molecule. Interestingly, for H2O on Sb atom, we observed a bond formation between the top first surface layer Sb and the fourth surface layer Sb of Sb–Sb = 3.136 Å. This indicated that the top surface Sb relaxed deep into the surface. The calculated adsorption energy of –6.37 kJ/mol was obtained for Pt–OH2 adsorptions, while the adsorption on Sb–OH2 gave +10.34 kJ/mol. This showed that there was poor interaction of water on Sb atoms compared to the Pt atoms.