Electrochemically Induced Spillover and Diffusion on Pt(111): Peem Imaging, Kinetic Modeling and the Nemca Effect

Introduction Electrochemically induced oxygen diffusion on electrode surfaces plays an important role in solid state electrochemistry, especially in the context of electrochemical promotion of catalysis (EPOC), also referred to as non-faradaic electrochemical modification of catalytic activity (NEMCA) [1]. The Pt(O2)|YSZ system is a model system in solid state electrochemistry as well as for EPOC studies. Here, the so-called “spillover oxygen” is generated at the three-phase boundary of solid electrolyte (YSZ, yttria-stabilized zirconia), electrode (Pt) and gas phase during anodic polarization and diffuses onto the electrode surface. While spillover itself is a well-known phenomenon, the detailed mechanism of the NEMCA effect is still subject of discussion. In order to gain more insight into these processes we have performed a combined experimental and theoretical study.