Unconventional interplay between heterovalent dopant elements: Switch-and-modulator band-gap engineering in (Y,...

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Cerium dioxide (CeO2) is a versatile material with potential applications in catalysis and energy.
• Doping CeO2 with trivalent yttrium (Y) can induce oxygen vacancies and modify its electronic properties.
• The role of other dopants, like cobalt (Co), in modulating these effects is not fully understood.

Purpose of the Study:

• To investigate the unconventional interplay between cobalt (Co) and yttrium (Y) dopants in CeO2.
• To elucidate the mechanism behind Co-induced activation of Y-modulated band gap reduction.
• To explore the potential of this doping strategy for band gap engineering in nanocrystal materials.

Main Methods:

• Experimental synthesis and characterization of Co and Y co-doped CeO2.
• Synchrotron-radiation x-ray diffraction for structural verification.
• Density functional theory (DFT) calculations for theoretical explanation of electronic structure changes.

Main Results:

• Co dopants act as a switch, activating the dormant band gap reduction effect of Y.
• Oxygen vacancies incurred by Y doping facilitate the lowering of the Co 3d band.
• Hybridization of Co 3d and Ce 4f bands leads to significant band gap narrowing.
• Experimental observations are consistent with DFT predictions.

Conclusions:

• An unconventional switch-and-modulator scheme for band gap engineering in CeO2 has been demonstrated.
• The interplay between Co and Y dopants offers a novel approach to tune material properties.
• This research paves the way for advanced applications in environmental protection and solar energy harvesting.