“…Ultrathin metal lms composed of one or few layers supported on at or stepped transition-metal (TM) surfaces have been considered as promising catalysts for several reactions due to the possibility to tune their chemical activity by controlling substrate strain, composition, and ligand effects. [1][2][3] TM layers supported on TM surfaces, such as (111), (100), and (110), have been widely studied, e.g., Fe, Co, Ni, and Pd on Au(111) and Au(110), [4][5][6][7][8][9] Co/Ag(111), 7 Co and PtAu on Pt(111), 10,11 Pt and Au on Ni(110), [12][13][14] Pt/Ni(111), 15 Pt and Au on Ru(0001), 16 Ag and Au on Cu(100), 17 Au/Cu(110), 18 Ag and Au on Pd(100), 17 and Au/Ir(111). 19 Among those systems, Pt layers supported on Au surfaces have attracted a great interest, in particular, for the designing of high performance fuel cell electrocatalysts to improve oxygen reduction reactions.…”