Relay-Enhanced Electron Transfer in Triple-Layer Ru@Ir@Pt Core-Shell Nanoparticles for the Ammonia Oxidation Reaction

Ammonia oxidation reaction (AOR) is important for enabling the efficient use of NH₃ as a promising carrier for hydrogen storage and transportation. However, the catalytic activity of state-of-the-art Pt-based catalysts decreases significantly due to the strong adsorption of N species. In this study, a triple-layer core-shell structured Ru@Ir@Pt model catalyst was employed to demonstrate that the relay electron transfer strategy can decelerate the adsorption of N species and increase AOR activity, a process facilitated by the built-in electric field (BEF) induced by differing work functions that drive the sequential relay of charge transfer across the interfaces between different metals. In situ Fourier Transform Infrared (FTIR) spectroscopy revealed that AOR proceeds primarily via the N₂H₄ pathway of the G-M mechanism. Both the experimental and theoretical simulation results confirm that relay electron transfer induced by a built-in electric field enables the outermost Pt electron-rich state to reduce the intensity of N adsorbed species and lower the energy barrier of rate-determining step in the AOR, resulting in excellent activity with a mass activity reaching up to 363.5 A g^-1. This value is 5.24 times higher than that of 20% Pt/C and significantly surpasses most previously reported catalysts. This work presents a novel material design approach for developing high-performance advanced ammonia oxidation electrocatalysts.