Coordination-Controlled Stability of Pd Single-Atom Catalysts under Electrochemical Conditions

Single-atom catalysts (SACs) maximize atom utilization and site-specificity for diverse chemical and electrochemical transformations. While activity and selectivity have been optimized through advanced synthetic methods, the electrochemical stability of SACs remains insufficiently understood and limits practical application. Here, we employ operando inductively coupled plasma mass spectrometry (ICP-MS) to quantify the dissolution kinetics of palladium (Pd) SACs in acidic electrolyte across a wide potential window. Operando electrochemically coupled mass spectrometry (EC-MS) confirms concurrent carbon support corrosion. By systematically varying heteroatom dopants, applied potentials, electrolyte pH, and adsorbing anions, we decouple coordination-driven (intrinsic) and electrochemical (extrinsic) factors controlling metal leaching. Specifically, the external potential exhibits a more pronounced influence on the stability of Pd SACs, while the coordinating heteroatoms modulate stability through both direct interaction with the isolated Pd centers and influence on the carbon support. Complementary X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) reveal dynamic restructuring of the Pd coordination environment, linking local chemical structure to macroscopic stability. These results provide mechanistic insights into SAC degradation pathways and establish design principles for stable single-atom architectures in energy conversion applications.