Energy Conversion Processes in Catalytic Electrolyte-Free Metal-Oxide Nanostructures

Over the past decade, a wide range of investigation has been carried out toward the development of high performance energy conversion devices. An interesting trend in the modern energy conversion research is an increased interest in electrolyte-free device concepts. In this presentation, we introduce a new type of device architecture based on an electrolyte-free catalytic metal-oxide nanostructure for conversion of chemical energy to electrical energy. In this device, a reaction-induced current is generated upon exposure of hydrogen and oxygen gases on a catalytic nanomesh metal (e.g. Pt, Rh) and a mesoporous oxide layer (TiO₂). Interestingly, the reaction current kinetics revealed a new second mode of the reaction in addition to the usual catalytic oxidation of hydrogen to water. This mode induces a negative stationary reaction current at room temperature conditions. This production of negative current cannot be explained with any known mechanisms i.e thermal and hot electron. Instead, protons spillover from Pt to TiO₂ substrate resulted in higher energy conversion efficiency compared to metal single-crystal systems. The number of charge carriers per one hydrogen molecule oxidized at Pt/TiO₂ surface may reach 0.04 at room temperature, which is much higher than the values reported in pervious studies.