Structural, electronic and adsorption properties of V–Rh(111) subsurface alloy

Abstract

V–Rh(111) bimetallic systems were prepared by deposition of 0.4 and 2.5ML of vanadium on Rh(111) surface at 823K and by annealing up to 1023K. Subsurface alloys of similar composition and electronic structure were formed. On the latter one, (2×2) surface reconstruction was observed. Electronic structure of the V–Rh(111) subsurface alloys was studied by photoelectron spectroscopy utilizing synchrotron radiation. Atomic structure was studied by means of LEED and X-ray photoelectron diffraction. Chemisorption properties were probed by CO and O2 adsorption. The topmost atomic layer with (2×2) reconstruction consisted exclusively of Rh atoms. The obtained results indicate formation of alloy with Rh3V composition and L12-type structure. Changes observed in the electronic structure were correlated with lower reactivity towards CO adsorption. The photoemission data indicate that the CO saturation coverage at 300K is reduced to less than half on the alloy surface as compared to clean Rh(111). Oxygen adsorbed on the alloy surface strongly interacted with the subsurface vanadium and induced formation of a surface vanadium oxide.