Electron Probe Bridging Solid-State Chemistry and Surface Chemistry: Example of the TiO2‑O2 System

This work reports the capacity of a high-temperature electron probe to bridge solid-state chemistry and surface chemistry. This goal could be accomplished by performing the characterization of the surface layer in equilibrium with both the gas phase and bulk phase, thus dealing with a system governed by thermodynamic laws, which is free of unknown kinetic terms. In this work, we contemplate the use of the electron probe in surface defect engineering of the next generation of energy materials, that are expected to enhance the production of clean energy. The concept of this kind of engineering is considered for the TiO2-O2 model system. Such example demonstrates the role of surface segregation in the formation of a quasi-isolated surface structure, that has a profound impact on the reactivity of solids and their performance in energy conversion devices. Consequently, it is essential that studies of the effect of surface defect structure on the reactivity of solids are conducted in situ and in operando, under conditions of real application. This is expected to aid directly the rational design of surface properties in the processing of high-performance energy materials for fuel cells, solar cells, batteries, catalysts and photo-catalysts, as well as sensors.