Effect of Gd3+ doping on structural and photocatalytic properties of ZnO obtained by facile microwave-hydrothermal method

Abstract

Gd 3+-doped ZnO nanoparticles with different Gd 3+ concentrations were synthesized by an eco-friendly microwave hydrothermal method. X-ray diffraction measurements confirm that the prepared nanoplates exhibit hexagonal wurtzite structure. Gd 3+ doping induces lattice expansion of ZnO due to the larger ionic radius of rare earth Gd 3+ in relation to Zn 2+ ions. Rietveld refinement, Raman and Photoluminescence (PL) spectra confirm that Gd 3+ ions were successfully inserted into ZnO lattice. The 2.0 mol% Gd 3+ doped sample exhibits an increased photoluminescence intensity in comparison to that for the undoped ZnO, which is attributed to the enhance in the defect concentration due to Gd 3+ doping. The photocatalytic activities of the samples were also evaluated towards UV-A induced degradation of methylene blue in aqueous solution. The highest photocatalytic activity was observed for 1.0 mol% Gd 3+-doped ZnO nanoparticles (73% for methylene blue degradation within 150 min under UV-Vis irradiation). The particles size, agglomeration degree and the electronic effects due to the Gd 3+ dopping seems to be the main parameters that affect the photocatalytic activity of Gd 3+-doped ZnO nanoparticles.

Synthesis, characterization, photocatalytic application of Gd/K co‐doped ZnO

“…Since the decrease in particle size will also cause an increase in the surface and thus the adsorption on the surface, the interface will have an effective photocatalytic activity due to the increase in the transfer rate of charge carriers 15 . In the studies, it was determined that the charge‐carrying capacity of the photoanode increased and the recombination rate decreased with the contribution made to the photoanodes used in dye‐sensitized solar cells 21,27,28 . As explained in Section 2.4, it can be given that Gd/K co‐doped ZnO demonstrated higher absorption ability than undoped ZnO for the first 30 min in the dark.…”

Photoluminescent neodymium-doped ZnO nanocrystals prepared by laser ablation in solution for NIR-II fluorescence bioimaging

“…Typically, redistribution of the ZnO peaks intensities indicates the distortion of its lattice that may be caused by the incorporation of dopant atoms. Wurtzite has an open structure with interstitials, thus the rare earth atoms may occupy Zn 2+ site or Zn interstitial position thus replacing or displacing Zn 2+ ions in the crystalline structure [ 25 ]. Due to the Nd 3+ ion larger ionic radius (0.94 Å) compared to the Zn 2+ ion (0.74 Å) [ 25 ] doping with neodymium introduces significant strain into the ZnO lattice and increases the amount of structural defects, such as oxygen vacancies.…”

“…Wurtzite has an open structure with interstitials, thus the rare earth atoms may occupy Zn 2+ site or Zn interstitial position thus replacing or displacing Zn 2+ ions in the crystalline structure [ 25 ]. Due to the Nd 3+ ion larger ionic radius (0.94 Å) compared to the Zn 2+ ion (0.74 Å) [ 25 ] doping with neodymium introduces significant strain into the ZnO lattice and increases the amount of structural defects, such as oxygen vacancies. In the both samples obtained in Nd(NO 3 ) 3 , the (002) and (101) diffraction peaks get shifted towards the lower angle that can be caused by the expansion of the unit cell along c and a-axes because of the large ionic radius mismatch.…”

Tuning the Optical Properties of ZnO by Co and Gd Doping for Water Pollutant Elimination

“…When Co or Gd ions are substituted for Zn ions in ZnO, there is a distortion of the crystal lattice, which can result in a change in the crystal structure. The distortion arises from the different electronic configurations and coordination environments of the Co and Gd ions compared to Zn ions [19,20]. These differences can lead to a relaxation of the crystal lattice, which causes an increase in the lattice parameters.…”