Engineering Dense Stacking Faults in Silver Nanoparticles for Boosting the Oxygen Reduction Reaction

Defect engineering is an efficacious strategy for optimizing the activity of catalysts, while traditional chemical synthesis has limited ability to generate a large number of defects due to the mild and equilibrium conditions. In this work, we show that a physical process, laser ablation in liquid, can prepare Ag nanoparticles with controllable defects due to its extremely nonequilibrium conditions. Particularly, the liquid nitrogen medium helps form abundant stacking faults which reduce the coordination number greatly and introduce high lattice tensile strain; these two factors jointly enhance the oxygen binding energy of Ag nanoparticles and significantly improve the ORR activity to an extent comparable to commercial Pt/C. When the Ag catalyst is applied in Zn-air batteries, the power density could reach 262.85 mW cm–2, much better than those of Pt/C and other reported Ag-based catalysts.