Morphology and size effects on the reduction of silver oxide by hydrogen

The dependence of reactivity towards hydrogen on size and morphology was studied for silver oxide Ag2O microparticles. Morphological tuning of the microparticles, which appeared in a size range from 340 to 1400 nm, was achieved in a wetchemical synthesis approach. Thermogravimetric measurements allowed the determination of onset temperatures and reaction rates for reduction with gaseous hydrogen as reducing agent. The results reveal the high complexity of the Ag2O reduction process, on which both the surface to volume ratio as well as the facet dependent activity of the morphologies have great influence. Differential scanning calorimetry was employed to study reduction by hydrogen,desorbing from a hydrogen-loaded palladium foil, showing great effect of contact area size on the reactivity.