Catalyst particles with a layered core-shell-shell structure and process for their preparation

摘要

Catalyst particle comprising a layered core-shell-shell structure according to the general formula (1) NM / ZS / EM (1) in which - NM is a non-noble metal core of the particle, - EM is a noble metal which forms the outer shell, ZS is an intermediate layer between the non-noble metal core and the outer noble metal shell, which is a base metal / noble metal alloy of the composition (NM) x (EM) y (where x and y are atomic ratios where x = 0.99 to 0.01 and y = 0 , 01 to 0.99, x + y = 1), wherein the atomic ratio of non-noble metal (NM) to noble metal (EM) in the intermediate layer (ZS) gradually decreases from the non-precious metal core toward the outer shell-forming noble metal (EM).