Role of Reaction Intermediate Diffusion on the Performance of Platinum Electrodes in Solid Acid Fuel Cells

Understanding the reaction pathways for hydrogen oxidation (HOR) and oxygen reduction (ORR) is key to design electrodes solid acid fuel cells (SAFCs). In general, electrochemical reactions of a cell are considered occur at triple-phase boundary where an electrocatalyst, electrolyte gas phase in contact. this concept, diffusion processes intermediates from catalyst remain unconsidered. Here, we unravel open-structured Pt with various electrode thicknesses 15 240 nm. These characterized by length thickness-depending double-phase area. We reveal that active catalytic interface HOR. For layers ≤ 60 nm, HOR rate rate-limited gas/catalyst and/or catalyst/electrolyte while surface step fast. thicker (>60 nm), on becomes limiting process. ORR, predominant pathway via boundary. The contributes additionally few nanometers. Based our results, propose molecular mechanism interfaces based upon concept may need be extended effective area near include all catalytically relevant intermediates.