Synthesis, Characterization, and Photocatalytic Activity of Zn-Doped SnO₂ Hierarchical Architectures Assembled by Nanocones

Abstract

Zn-doped SnO2 hierarchical architectures with nanoflower, nanourchin, and nanotrepang morphologies have been synthesized with a surfactant-free solvothermal synthesis route in the mixed solvents of ethylenediamine (En), ethanol, and deionized water. The observations of field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) showed that Zn-doped SnO2 hierarchical architectures with different morphologies were assembled by the nanocones with diameters ranging from 20 to 60 nm. We found that the alkaline dosage (NaOH) of the solution had a remarkable effect on the morphology of as-synthesized products. The UV−visible spectra of Zn-doped SnO2 hierarchical architectures exhibited a blue shift with the decrease of the size of nanocones. The photocatalytic activity of Zn-doped SnO2 samples were evaluated by the degradation of RhB aqueous solution, and the results revealed that the sample with urchin morphology had high photocatalytic activity efficiency. Moreover, the degradation process of RhB induced by Zn-doped SnO2catalyst was investigated in detail as well.

Nature of Paramagnetic Species in Nitrogen-Doped SnO2: A Combined Electron Paramagnetic Resonance and Density Functional Theory Study

“…This can be understood considering the shift observed for these lines (some of them are evidenced in the figure) passing from Figure 1a to Figure 1b. The shift exactly corresponds to the difference in the position between the outer lines of the 15 N and 15 N hyperfine structures, respectively. We are thus in the presence of a complex EPR signal resulting from a paramagnetic centre in which the unpaired electron interacts with both N and Sn atomic species.…”

“…This allows to exclude the surface nature of the paramagnetic centre. Figure 1 compares the X-band spectra (microwave frequency, ν = 9.50GHz) obtained using 14 Figure 1, where the stick diagrams indicate the presence of a triplet ascribed to 14 N containing centre ( Figure 1a) and of a doublet attributed to 15 N ( Figure 1b). In this latter case, the trace of the 14 N triplet (30%) is still observed.…”

“…The last isotopomer (three magnetic *Sn, Table 1, column 5) has negligible abundance and has not been considered. Figure 3 provides an overall view of all the simulations by comparing the experimental and the simulated traces for 14 N (X-band, Figure 3a), 15 N (X-band, Figure 3b) and 14 N (Q-band, Figure 3c). In all cases the same set of parameters (g and A) was used.…”

“…Two distinct 15 N containing N-SnO 2 samples were also prepared using 70% and 98% 15 N enriched NH 4 Cl sample following the same procedure above described.…”

“…By contrast to the case of the anatase TiO 2 , for which the doping of its crystal structure has been extensively studied by taking advantage of its sensitiveness to the introduction of punctual defects resulting from its 3d 0 electronic configuration 12,13 , there are only very few reports dealing with doping for shifting SnO 2 's absorption tails towards visible light. 14,15,16 The inclusion of nitrogen dopant into the SnO 2 lattice is a credible approach to tune the absorption properties, either via bandgap narrowing or by introducing new energy states into the gap. N-SnO 2 films have been prepared by magnetron reactive sputtering in gas mixtures of nitrogen and oxygen.…”