An Atomistic View of Electrodics at the Platinum Surface

Platinum (Pt) is a benchmarked catalyst for several electrochemical processes, however an atomistic insight into its electrodics at the electrode-electrolyte interface is still lacking. In this study, we aim to capture the chemical changes of Pt surfaces brought on by an applied potential in an electrolyte of pH~5, which can address the catalytic efficacy and stability of different crystallographic orientations under varying applied bias. Through a combined experimental and reactive molecular dynamics simulation approach, we uncover the effect of charge build up on the surface of the Pt electrode, which can be directed towards capacitive and faradaic processes. By introducing a simulated applied potential, which is compared to experimental potential by equating charge density ( in the range -0.2 mC/cm2 to 0.2 mC/cm2 ), we unravel the electrochemical processes on Pt (in slightly acidic pH). At reductive potentials of ~0.3-0.0 V vs RHE, we visualize phenomenon such as under potential hydrogen adsorption (HUPD) and hydrogen evolution/oxidation reaction. While oxidative potentials in the range ~1.2-1.6 V vs RHE see platinum oxide (Pt-O) formation, and platinum leaching off the surface. The theoretical potential and plane dependence of these phenomenon (HUPD, Pt-O, etc.) are verified with experiments, and hence it brings a new platform for computationally viable electrode-electrolyte studies.