Catalysis on nanoporous gold–silver systems: Synergistic effects toward oxidation reactions and influence of the surface composition

Au–Ag/CeO2 and Au–Cu/CeO2 Catalysts for Volatile Organic Compounds Oxidation and CO Preferential Oxidation

“…In contrast in the Au-Ag/CeO 2 sample the surface composition is quite different from that of the corresponding monometallic samples with a strong enrichment in Au and a moderate impoverishment in Ag, resulting in a Ag/Au surface ratio of 1.08, quite near to the bulk one. This is compatible with the formation of a Au-Ag alloy or linked monometallic nanoparticles [28,54]. …”

“…A similar, but less evident, positive effect was observed in the case of the bimetallic Au-Cu/CeO 2 sample. Some examples of synergism between gold and copper or silver, giving superior performance respect to the corresponding monometallic gold catalyst have been reported in the literature [25,27,54,60]. Sandoval et al stated that the synergistic effect between Au and Ag supported on TiO 2 results in significantly higher activity in CO oxidation and better stability than the monometallic gold catalyst [27].…”

“…Sandoval et al stated that the synergistic effect between Au and Ag supported on TiO 2 results in significantly higher activity in CO oxidation and better stability than the monometallic gold catalyst [27]. Déronzier et al observed a strong interaction between gold and silver, that resulted in a higher CO oxidation selectivity at low temperature, ascribed to a large segregation of silver inhibiting the H 2 adsorption [54]. Liao et al highlighted that the synergistic effect between Au and Cu over ceria was highly dependent upon the Cu/ Au atomic ratio and the thermal treatment, with the best performance obtained over reduced catalysts, due to a decrease in the amount of surface copper species upon reduction treatments [25].…”

“…On the Au-Ag/CeO 2 sample, instead, the surface gold and silver compositions were quite different from those of the monometallic samples with a Au enrichment and a Ag impoverishment. It can be reasonably suggested that in the Au-Ag/CeO 2 bimetallic sample a strong Au-Ag interaction (formation of a stoichiometric Ag-Au alloy or linked monometallic particles) occurs, promoting the dispersion of gold and enhancing the catalytic performance [28,54]. Sasirekha et al proposed that the occurrence of this strong interaction between Au-Ag boosted the performance of the PROX reaction by increasing the stability of catalysts [28].…”

Influence of the partner oxide on the catalytic properties of Au/Ce x Zr 1 − x highly loaded gold catalysts

“…Method for producing the different catalysts studied herein is already described elsewhere [29][30][31]. Here, this two steps method has been also applied to ternary (Au-CeZr) intermetallics in order to synthesize an intimate mixture of a skeletal gold structure with nanostructured oxide (ZrO 2 , CeO 2 ).…”