Electron probe for surface science and surface defect engineering of oxide semiconductors for energy conversion

This work provides a summary of progress in emerging areas of the science of materials interfaces and interface engineering of energy materials. The progress, which is focused on gas-solid reactivity of oxide materials, indicates that the high-temperature electron probe (HTEP) offers new insight into the local defect-related properties of the surface layer that are critical for understanding the reactivity of solids and the related charge transfer. The probe enables unequivocal surface characterization of energy materials in gas–solid equilibrium and in-situ surface monitoring during processing and performance at elevated temperatures. Specific progress has been achieved in understanding the impact of both chemisorption and surface segregation on the formation of quasi-isolated surface structures (QISSs) that play a crucial role in gas–solid reactivity. The key feature of the HTEP is the ability to measure work function (WF), which is the defect-related surface property, while the surface layer is in thermodynamic equilibrium with the gas phase on one side and the bulk phase on the other. The summary indicates that the progress in energy materials requires recognition that surface properties are determined by structural defects within the surface layer. The probe, which has a wide range of applications in materials engineering, ceramics, catalysis, chemical engineering, metallurgy, nuclear fusion and high-temperature materials, opens up new areas of the science of materials interfaces and interface engineering. The latter is of critical importance in the development of materials for environmentally friendly energy conversion.