Tuning the photocatalytic activity of ZnO nanoparticles by the annihilation of intrinsic defects provoked by the thermal annealing

Evidence of progressive Fe2+ to Fe3+oxidation in Fe2+-doped ZnO nanoparticles

“…It is herein hypothesized that the above-mentioned mode could be adsorbed by the NPs' surface from the reaction medium and by handling the samples in the air atmosphere. On the other hand, the inorganic vibrational frequency of the Zn-O is observed below 700 cm -1 , which is specifically located at ~423 cm -1 for the undoped ZnO NPs, slightly below the value (~431 cm -1 ) reported in the literature [5]. Furthermore, an additional vibrational mode, possibly associated with a secondary iron oxide phase has not been observed within the limit of detection of the FTIR equipment (expected for Fe 2 O 3 in the range of 578-567 cm -1 [30]).…”

“…In the second(Figure 6 (g)), the half-width excitonic peak broadens while the continuous part almost maintains its shape, the contribution increases. Figure 7 shows the FTIR spectra of the undoped and Fe-doped ZnONPs, all of which exhibit the expected spectra of the ZnO structure [5]. However, due to neighborhood modifications, iron-ions are located into the core or onto the surface of the ZnO NPs lead toFTIR spectra displaying considerable alterations.…”

“…5 Moreover, the PCA tests of the ZnO NPs do not show a straightforward dependence on the NPs’ size, but it seems to be correlated with the density of defects. 5 In addition, Rokhsat et al reported the PCA of Fe-doped ZnO nanosheets on the p -nitrophenol degradation under visible light, revealing the high performance of the Fe-doped sample compared to the undoped one. 3 On the other hand, based on the Langmuir isotherm analysis, ZnO nanocrystals decorated with regenerated microfibrillated cellulose scaffolds and containing 41 wt% ZnO were found to be very efficient in removing As(V) from water with a maximum capacity of 4.421 mg g −1 , at neutral pH (7).…”

“…Regarding their applications, one can highlight their use in wastewater treatment processes. In this scenario, Andia-Huarachaet al, reported the photocatalytic activity (PCA) of ZnO nanoparticles (NPs) synthesized via the polymeric precursor method and presenting mean crystallite size in the range of 23-150 nm [5]. Moreover, the PCA tests of the ZnO NPs do not show a straightforward dependence on the NPs' size, but it seems to be correlated with the density of defects [5].…”

“…In this scenario, Andia-Huarachaet al, reported the photocatalytic activity (PCA) of ZnO nanoparticles (NPs) synthesized via the polymeric precursor method and presenting mean crystallite size in the range of 23-150 nm [5]. Moreover, the PCA tests of the ZnO NPs do not show a straightforward dependence on the NPs' size, but it seems to be correlated with the density of defects [5]. In addition, Rokhsatet al reported the PCA of Fe-doped ZnO nanosheets on the p-nitrophenol degradation under visible light, revealing the high performance of the Fe-doped sample compared to the undoped one [3].…”