“…The global reaction is the following: Starting from the work of Hörold et al [5], numerous studies have been aimed at the development of suitable catalysts for nitrate reduction [6][7][8][9][10]. The addition of a second metal such as copper [6,11], silver [12], tin [10,[13][14][15], indium [10,[16][17], or two metals [18] to a noble metal on various supports leads to an important change in its activity and product selectivity. The proposed mechanism involves a redox reaction between the promoter, in its reduced state, and nitrate, leading to intermediate nitrite or directly to nitrogen gas or ammonium ion, and to an oxidized form of the promoter [9].…”