Highly active surfaces of noble metals by thermal treatment under UHV

Abstract

H 2PtCl 6·6H 2O was decomposed at 673 and 1073 K under 10 -7 Pa. XRD and XPS observations showed that the powders obtained from the decomposition of H 2PtCl 6·6H 2O were completely reduced to metallic Pt without any further reduction being required. The XRD pattern of the obtained Pt powders showed that the peaks of the high-index faces (220), (311), (222), (400), (331), and (420) relative to the (111) face increased markedly. The violent evolution of gases during the decomposition of H 2PtCl 6·6H 2O may make the surface rough. The obtained Pt powders exhibited high activity for the H 2-D 2 exchange reaction. The small amount of residual chlorine on the surface showed negligible effect on both the activity and the valence band. The high activity of the Pt powder is ascribed to the increased high-index faces which might contain dense step structures.