Polyaniline-Supported Atomic-Level Pt and Pt-Au Clusters as Catalytic Electrodes in Propanol Oxidation

Noble metals are widely recognized for their ability to catalyze the electro-oxidation of organic compounds, with smaller particle sizes significantly enhancing electrocatalytic activity. In this study, catalytic electrodes decorated with atomic-level platinum and Pt-Au clusters were fabricated using cyclic atomic-metal electrodeposition. The interactions between the iminium (protonated imine) groups in emeraldine salt polyaniline (PANI) and metal chloride complexes in the electrolyte enabled precise control over the cluster size and composition. The electrocatalytic activity of these electrodes for propanol oxidation was systematically evaluated using cyclic voltammetry (CV). Notably, PANI electrodes decorated with odd-numbered atomic-level Pt clusters exhibited higher peak oxidation currents compared to even-numbered clusters, revealing a unique even-odd effect. For atomic-level Pt-Au clusters, the catalytic activity was significantly influenced by the sequence of Pt and Au deposition, with PANI-Au₁Pt₃ achieving the highest catalytic activity (35.34 mA/cm²). Bi-metallic clusters consistently outperformed mono-metallic clusters, and clusters containing only one Pt atom demonstrated superior catalytic activity. These findings provide valuable insights into the design of high-performance catalytic electrodes by leveraging atomic-level control of the cluster size, composition, and deposition sequence, paving the way for advanced applications in electrochemical sensors.