Supplementary information files for "Nanoscale confinement‐induced atom‐milling Pd nano‐sheets into ultra‐fine Pd3Co Alloys"

Atomic regulation of nanocatalysts is of both scientific and technological importance in efficient hydrogen energy conversion technology. Here a feasible nanoscale confinement‐induced atom‐milling (NCAM) method is reported to synthesize and atomically mesh 1 nm thick Pd metallic films into ultra‐fine Pd3Co nanoalloys. The nano‐sized inner space of layered crystalline provides a nano‐scaled limitation (1.3 nm) for atoms’ collision, which forces the assembly of hydrogen or Co atoms into a Pd lattice to expand or contract crystal as atom‐milling. The resulting ultra‐fine Pd3Co nanoalloys exhibit nearly three times higher activity than commercial Pt/C for oxygen reduction reaction, and 2.3 times higher activity than Pd/C for formic acid electrooxidation reaction, for fuel cells, and wider electrocatalysis applications.