N.J. Ray, E.G. Karpov
University of Illinois at Chicago,
Keywords: mesoporous titania, plasma electrolytic oxidation, reaction current, proton spillover
Summary:Investigation of heterogeneous catalysis using bifunctional systems of nanodispersed Pt on porous oxide substrates is important for a broad range of applications including photocatalysis, fuel cells, solid state chemical sensors, and many others. Active transducers exhibit great potential through their ability to convert excessive surface-released chemical energy into an electric current in an electrolyte-free system. We report on a mesoporous TiO2 system that has been synthesized by a plasma electrolytic oxidation process. The porous TiO2 structure is then decorated with an electrically continuous array (mesh) of Pt nanoparticles; this nanocomposite generates an electrical signal when subjected to catalytic oxyhydrogen reactions on its surface. We discuss the water turnover frequency during generation of stationary current under a room temperature regime. A correlation between water production and reaction current generation will be outlined, providing evidence for the production of water as the dominant force behind the generated electromotive force under steady-state conditions. The impact of Pt phase microscopic structure on the reaction current magnitude is also investigated. These results shed light on the underlying and competing processes within the Pt/TiO2/Ti system during the oxidation of hydrogen and the generation of a room temperature stationary reaction current with a potential for novel, one-compartment hydrogen fuel cell devices.