Potential-Controlled Pd Segregation on Au–Pd Alloy Nanoparticles

The pledge to curb CO2 emissions with the help of clean energy is an ambitious undertaking, one that is tasked with the development of durable electrocatalysts for fuel cells and electrolyzers. Recent development of gold–palladium (Au–Pd) alloy nanoparticles outlines a contemporary strategy in combining the synergistic effects of a more electrochemically stable gold (Au) metal with catalytically active palladium (Pd). Unfortunately, not all compositions are optimal for an intended application, which requires further fine-tuning─a task that seems difficult with the prevalent wet-chemical synthetic methods. Here, we demonstrate a new approach for fine-tuning surface composition in Au–Pd nanoparticles via a procedure involving the selective diffusion of Pd atoms from the core to the surface induced by the adsorption of oxygen atoms at the surface of Au–Pd NPs. Going forward, a similar technique can be more generally applied toward development of ‘self-healing’ electrocatalysts that can alter properties suiting different external requirements with a simple switching of voltage, or a controlled pretreatment.