Tuning Reaction Pathways of Electrochemical Conversion of CO2 by Growing Pd Shells on Ag Nanocubes

Y The electrochemical carbon dioxide reduction reaction (CO2RR) has been studied on Ag, Pd, Ag@Pd1-2L nanocubes using a combination of in situ characterization and density functional theory calculations. By manipulating the deposition and diffusion rates of Pd atoms on Ag nanocubes, Ag@Pd core-shell nanocubes with a shell thickness of 1-2 atomic layers have been successfully synthesized for CO2RR. Pd nanocubes produce CO with high selectivity due to the transformation of Pd to Pd hydride (PdH) during CO2RR. In contrast, PdH formation becomes more difficult in Ag@Pd1-2L core-shell nanocubes, which inhibits CO production from the *HOCO intermediate and thus tunes the reaction pathway toward HCOOH. Ag nanocubes exhibit high selectivity toward H-2, and there is no phase transition during CO2RR. The results demonstrate that the CO2RR reaction pathways can be manipulated through engineering the surface structure of Pd-based catalysts by allowing or preventing the formation of PdH.