Interface Sensitivity in Electron/Ion Yield X-ray Absorption Spectroscopy: The TiO₂-H₂O Interface.

Area of Science:

• Surface science
• Materials science
• Electrochemistry

Background:

• Understanding solid-liquid interfaces is vital for applications like corrosion, energy storage, and electrocatalysis.
• Direct chemical information at these interfaces is challenging to obtain.
• X-ray absorption spectroscopy (XAS) offers potential for interface analysis.

Purpose of the Study:

• To investigate the solid-liquid interface between titanium dioxide (TiO2) and water using XAS.
• To demonstrate the sensitivity of electron-yield XAS to interfacial chemical states.

Main Methods:

• A thin TiO2 film was deposited on a SiN window, serving as an electrode in a flow cell.
• Electron-yield XAS was employed, collecting spectra from emitted electrons.
• Drain currents were measured at working and counter electrodes.

Main Results:

• Electron-yield XAS spectra were sensitive to the solid-liquid interface within nanometers.
• The water layer adjacent to anatase TiO2 exhibited spectral features similar to ice.
• Identical but opposite drain currents were observed between electrodes.

Conclusions:

• Electron-yield XAS is a powerful technique for probing interfacial chemistry.
• The study provides insights into the structure of water at the TiO2-water interface.
• This method has significant potential for studying electrode-electrolyte interfaces in various applications.