Reduction of binary silver-copper ion mixture in mordenite: an example of synergetic behavior

摘要

Mordenite exchanged with mixture of (Ag~+,Cu~(2+))-ions was reduced in hydrogen flow. Variations of the Ag/Cu ratio and reduction temperature influence the appearance of silver and copper reduced species. They were detected by means of optical absorption using diffuse reflectance spectroscopy technique as the characteristic peaks of size selected Ag_8 clusters and plasmon resonance band of copper nanoparticles. Changes in the temperature range of appearance and disappearance of distinct copper and silver species and variations of their relative stability were revealed. Formation of bimetallic particles was not detected. The observed effects are interpreted as a mutual influence of silver and copper ions and reduced species of silver and copper due to their concurrence for ion-exchange sites and relative positions in mordenite voids, respectively.