Hydrogen adsorption study on nanostructured Ag–Rh films grown by supersonic cluster beam deposition

Following recent literature work, an interesting result on hydrogen sorption by Ag–Rh clusters was reported which do not follow the common understanding of hydrogen absorption in bulk alloys. Thus, nanostructured Ag–Rh films with a composition of 75% Ag–25% Rh were grown by supersonic cluster beam deposition onto microbalance quartz crystals in order to measure hydrogen absorption. The films were exposed to H2 gas to study hydrogen absorption at different partial pressure. The Ag–Rh films were then characterized by XPS and AFM. The Ag/Rh atomic ratio was found to be 75/25 by XPS. Surface roughness was determined by AFM to be 3 nm RMS in all the films. In disagreement with the quoted literature report, no hydrogen absorption was observed in our Ag–Rh films up to 5.3×103Pa of hydrogen pressure. The response of the balance was checked and validated by measuring hydrogen absorption on 10 and 100 nm Pd films. The hydrogen absorption by Pd yielded an atomic H/Pd ratio of ∼0.65 in agreement with our prior measurements.