In this study, three different Ag micro/nano leaves were successfully synthesized through a galvanic displacement reaction by adjusting the concentration of Ag+. The catalytic activities of the prepared Ag micro/nano leaves toward ORR showed strong dependence on their morphology. An optimal concentration of Ag+ can result in a well-defined Ag micro/nano leaves with both crystallization and surface area, which showed the best activity towards ORR in alkaline media. In addition, the prepared Ag micro/nano leaves also showed high activity towards CO2 reduction, which required a potential of -0.8 V versus RHE to selectively convert CO2 to CO with the faradaic efficiency at about 20%. Compared with the Ag plate at the same overpotential, the FE has increased by 5-fold.