Exploring the structural conditions favoring Au anionic behavior on Au doped CeO₂

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• Gold-doped ceria (Au-CeO2) is a promising material for various applications.
• Understanding the chemical state and behavior of gold within the ceria matrix is crucial for optimizing its performance.

Purpose of the Study:

• To systematically investigate the synthesis and characterization of Au-doped CeO2.
• To identify conditions leading to the observation of anionic gold species.
• To elucidate the role of gold substitution and defect formation in Au-CeO2.

Main Methods:

• Experimental techniques including infrared spectra, X-ray diffraction, UV-vis spectroscopy, SEM, EDS, and X-ray photoelectron spectroscopy.
• Computational simulations using density functional theory (DFT) to model gold adsorption on CeO2 surfaces.
• Bader charge analysis to determine charge distribution and chemical character of gold.

Main Results:

• Successful incorporation of gold into CeO2 was confirmed by multiple spectroscopic and diffraction methods.
• Increased gold concentration led to more defects and a reductive chemical environment.
• DFT modeling identified the most stable adsorption sites for gold on the CeO2 (111) surface, often involving oxygen vacancies.
• Anionic gold species were experimentally observed, particularly at low gold concentrations, correlating with gold substituting oxygen atoms.

Conclusions:

• Anionic gold species can be present in Au-doped CeO2 materials, a state not previously considered.
• The anionic character of gold is promoted by its substitution of oxygen atoms within the ceria lattice.
• These findings provide new insights into the fundamental chemistry of Au-CeO2 and have implications for catalyst design and application.