TY - JOUR
T1 - On the Importance of Nanoparticle Necks and Carbon Impurities for Charge Trapping in TiO2
AU - Elser, Michael J
AU - Neige, Ellie
AU - Berger, Thomas
AU - Chiesa, Mario
AU - Giamello, Elio
AU - McKenna, Keith
AU - Risse, Thomas
AU - Diwald, Oliver
N1 - © 2023 The Authors. Published by American Chemical Society.
PY - 2023/5/11
Y1 - 2023/5/11
N2 - 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.
AB - 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.
U2 - 10.1021/acs.jpcc.3c00430
DO - 10.1021/acs.jpcc.3c00430
M3 - Article
C2 - 37197384
SN - 1932-7447
VL - 127
SP - 8778
EP - 8787
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 18
ER -