The Relationship between the Electronic State of Pt in Pt-Based Nanoparticle Catalysts and Their Electrochemical Catalytic Activity in the Oxidation of Small Organic Compounds.

To examine the relationship between the electronic state of platinum (Pt) in Pt-based nanoparticle (NP) catalysts and their catalytic activities in the electrochemical oxidation of methanol (MeOH) and ethanol (EtOH) in alkaline aqueous solutions, Pt-based NP catalysts were synthesized; their electrocatalytic activities were evaluated by rotating electrode techniques; and the electronic state of Pt in Pt-based catalyst surfaces was analyzed via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). Finally, plots of the electrocatalytic activity vs electronic state of the Pt atoms on the catalyst surface were obtained. The plots exhibited a so-called volcano-type correlation, indicating that there is an optimum electronic state of Pt atoms on the catalyst surface for maximizing the MeOH and EtOH oxidation activities. In addition, the existence of the optimum electronic state was confirmed with adatom-modified Pt electrodes with Pb, Bi, In, Co, and Cu.