On the Importance of Nanoparticle Necks and Carbon Impurities for Charge Trapping in TiO 2 .
Michael J ElserEllie NeigeThomas BergerMario ChiesaElio GiamelloKeith P McKennaThomas RisseOliver DiwaldPublished in: The journal of physical chemistry. C, Nanomaterials and interfaces (2023)
Particle attachment and neck formation inside TiO 2 nanoparticle networks determine materials performance in sensing, photo-electrochemistry, and catalysis. Nanoparticle necks can feature point defects with potential impact on the separation and recombination of photogenerated charges. Here, we investigated with electron paramagnetic resonance a point defect that traps electrons and predominantly forms in aggregated TiO 2 nanoparticle systems. The associated paramagnetic center resonates in the g factor range between g = 2.0018 and 2.0028. Structure characterization and electron paramagnetic resonance data suggest that during materials processing, the paramagnetic electron center accumulates in the region of nanoparticle necks, where O 2 adsorption and condensation can occur at cryogenic temperatures. Complementary density functional theory calculations reveal that residual carbon atoms, which potentially originate from synthesis, can substitute oxygen ions in the anionic sublattice, where they trap one or two electrons that mainly localize at the carbon. Their emergence upon particle neck formation is explained by the synthesis- and/or processing-induced particle attachment and aggregation facilitating carbon atom incorporation into the lattice. This study represents a substantial advance in linking dopants, point defects, and their spectroscopic fingerprints to microstructural features of oxide nanomaterials.
Keyphrases
- density functional theory
- molecular dynamics
- iron oxide
- quantum dots
- electron transfer
- solar cells
- visible light
- electronic health record
- dna damage
- genome wide
- energy transfer
- electron microscopy
- multiple sclerosis
- mass spectrometry
- deep learning
- dna methylation
- white matter
- drug induced
- risk assessment
- diabetic rats
- dna repair
- atomic force microscopy