Elucidating reaction pathways in CO2 electroreduction: Case study of Ag and Cu2O@Ag catalysts

CO2 electroreduction is a prospective avenue to produce carbon-based fuels, yet atomic-level insights on the mechanistic origin of catalytic selectivity remains elusive. Taking the Ag and Cu2O@Ag electrocatalysts as examples, Fourier-transform infrared spectroscopy in conjunction with theoretical calculations reveal that the hollow-nanostructured Ag promotes CO production through a lower energy barrier of the rate-limiting *CO2 to *COOH, while the Cu2O-Ag boundaries in the honeycomb-like Cu2O@Ag reinforce CO2 physisorption and chemisorption on the catalyst surface. The interfaces of Cu2O@Ag facilitate CO hydrogenation and CC coupling, opening alternative reaction pathways toward CH4 and C2H4. More broadly, this study provides insights to develop effective electrocatalysts in CO2 electroreduction and beyond.