Reaction of H-2 with polyoxometalate supported Rhodium(0) and Iridium(0) nanoparticles in aqueous suspensions: a kinetic study

The kinetics of the reactions of H-2 with rhodium and iridium nanoparticles (NPs), in aqueous suspensions, were studied by following their catalytic reduction of PW12O403-, POM. The reaction of H-2 with the same size (similar to 2.5 nm) of two different nanoparticles was carried out to check how the nature of the nanoparticles affects the reaction kinetics. Herein we report the first kinetic measurement of H-2 + Rh-0 and Ir-0 NPs in the absence of an electric field. A comparison of the apparent rate constants of the reactions Rh-0-NPs and Ir-0-NPs + H-2 to the previously reported Pt-0-NPs + H-2 indicates that the rates decrease along the series k(Pt) > k(Rh) > k(Ir), though they are of the same order of magnitude. The adsorption of hydrogen and/or H atom can affect the structure of the M-0-NPs.