Fe‐Doped ZnO Nanoparticles: The Oxidation Number and Local Charge on Iron, Studied by ⁵⁷Fe Mößbauer Spectroscopy and DFT Calculations

Abstract

Iron bru: Fe-doped ZnO may contain Fe(2+) and Fe(3+) species. Whilst Mößbauer spectroscopy can distinguish these sites in pure oxides FeO and Fe(2)O(3), it gives very similar shifts for Fe-doped phases. This result is rationalized by electron redistribution from the dopant site to the crystal matrix. Mößbauer shifts correlate with the local charge on the Fe sites and different dopant sites can be identified by the Mößbauer quadrupole splitting (see figure).

In Silico Design of Optimal Dissolution Kinetics of Fe‐Doped ZnO Nanoparticles Results in Cancer‐Specific Toxicity in a Preclinical Rodent Model

“…The superimposed structure plot on the high‐resolution image of ZnO showed reasonable match with the hexagonal arrangement of the HR‐TEM image . These results clearly showed the overall lattice structure of ZnO was not structurally influenced through doping, and Fe was basically replacing Zn atoms in the wurtzite structure with +2 oxidation state . These results are in line with previous results obtained on the same NPs, demonstrating the high level of reproducibility between different batches .…”

Preferential oxidation of carbon monoxide over Pt–FeO /CeO2 synthesized by two-nozzle flame spray pyrolysis

“…We attribute the presence of Fe 2+ in the catalysts, at least in part of, to the doping in CeO 2 . This is consistent with the FSP synthesis of Fe-ZnO, in which the dopant ionic radius of Fe 2+ is the most compatible with the Zn 2+ host lattice[68,69].…”

Stabilization Mechanism of ZnO Nanoparticles by Fe Doping

“…We have also supported the experimental findings that Fe dopants stabilize ZnO NPs and distribute homogeneously inside the ZnO lattice. Moreover, based on the experimental and theoretical inner-shell and Möβbauer spectroscopy, we showed that Fe dopants occur in ZnO NPs predominantly with oxidation state Fe 2+ [8,9]. The reduction of ZnO NP toxicity has been recognized to be related to the suppression of Zn 2+ ion release to the solution, and the solvation process most probably will take place at the surface of the ZnO NPs [10].…”

“…Following the well-tested protocol of our earlier work [8,9], we have performed density-functional theory (DFT) calculations with the PBE0 hybrid functional [25] as implemented in the CRYSTAL09 code [26]. Full geometry optimization of atomic positions and cell parameters was performed for all studied models.…”

“…In the bulk, Fe-ZnO NPs contain mostly Fe 2+ cations [9]. Once a NP starts to dissolve, Fe atoms arrive at the topmost surface layer.…”