Decreasing the O₂-to-H₂O₂ Kinetic Energy Barrier on Dilute Binary Alloy Surfaces with Controlled Configurations of Isolated Active Atoms

Shifting from the typical 4e(-) pathway to H2O in electrochemical oxygen reduction to the 2e(-) pathway to H2O2 is increasingly recognized as an environmentally friendly approach for producing H2O2. However, the competitive 4e(-) pathway is a significant obstacle to the production of H2O2 since H2O is the thermodynamically favored product. Here, a series of Pt, Pd, and Rh active atoms diluted within inert-Au matrices with precisely controlled atomic arrangements and coordination environments are synthesized via facet engineering for O-2-to-H2O2 production. Surprisingly, individually dispersed Pt atoms within the Au surface enclosed by the square atomic arrangements exhibit superior H2O2 selectivity and achieve a maximum selectivity of 90% at 0.36 V versus the reversible hydrogen electrode. Operando synchrotron ambient pressure X-ray photoelectron spectroscopy identifies the presence of *OOH key intermediates on these isolated Pt active sites. Grand canonical density-functional theory also reveals that the kinetic energy barrier for the 2e(-) pathway (0.08 eV; OOH* + H+ + e(-) -> H2O2) on the isolated Pt sites is significantly lower than the 4e- pathway (0.29 eV; OOH* + H+ + e(-) -> O* + H2O). This work enables atomic-scale control in dilute binary alloy surfaces with specific configurations of isolated active atoms and provides essential guidance for catalyst design to boost O-2-to-H2O2 production.