Dynamic Strain-Engineered Au-Ag Alloy Nano-Seed Network for Enhanced Electrochemical Oxygen Reduction and...

The sluggish oxygen reduction reaction (ORR) is the limiting cathodic reaction for the low-temperature H₂-Air fuel cell. To overcome the limitations of Pt-based nano-scale materials, this work explores the possibility of a simple Au-Ag alloy-based nanosystem for enhanced fuel cell activity by exploiting their substantial electrocatalytic activity, stability, and durability toward ORR in an alkaline medium. This work further demonstrates how the ORR activity of this simple nanosystem can be further tuned by formulating an Au-Ag nanoalloy and manipulating their surface-ligand chemistry to generate a porous aggregated network structure with enriched crystal defects. The fabricated nanoalloy network follows a 4e- ORR pathway with a substantially low overpotential, demonstrating the role of molecular-level strain in enhancing its catalytic activity. The enhanced catalytic activity for the ORR mechanism is validated through first-principles calculations by modeling the twin boundary at the Au-Ag nanoalloy junction. In the system-level application, this catalyst shows a peak power density of 98.18 mW cm^-2 at a current density of 443.7 mA cm^-2 in a single-cell H₂-air fuel cell, comparable with a commercial Pt/C catalyst and even shows better performance at higher current density due to which it can serve as potential cathode catalyst in fuel cell devices.