In this paper, erbium-doped gadolinium oxide rare earth oxide nanoparticles (Gd 2 O 3 :Er 3+ ) with good light absorption capacity from the visible to the infrared region were prepared by polyol method, and then compounded with TiO 2 by hydrothermal method. SEM, TEM, XPS, UV–vis and electrochemical workstation were used to study the morphology, structure, UV–vis light absorption and photoelectrochemical (PEC) properties of Gd 2 O 3 :Er 3+ /TiO 2 . The results showed that the Gd 2 O 3 :Er 3+ spherical nanoparticles with a particle size of about 15 nm were uniformly distributed on the surface of the TiO 2 nanorod array, and the Gd 2 O 3 :Er 3+ /TiO 2 nanocomposites had good light absorption capacity in the infrared region. Furthermore, the photocurrent densities of Gd 2 O 3 /TiO 2 and Gd 2 O 3 :Er 3+ /TiO 2 were 2.08 and 2.75 times higher than those of TiO 2 , respectively, manifesting that the broadening of infrared light absorption can improve the PEC property of TiO 2 . Meanwhile, the DFT calculation results showed that the energy band of Gd 2 O 3 :Er 3+ /TiO 2 was significantly narrower than that of TiO 2 , indicating that Gd 2 O 3 :Er 3+ /TiO 2 had a redshift phenomenon of UV–vis absorption. The calculation results of state density showed that the f orbital of Gd 2 O 3 :Er 3+ intersected with the d orbital of TiO 2 , indicating that there is an electron transfer between Gd 2 O 3 :Er 3+ and TiO 2 .
Multifunctional luminescent materials are attracting attention nowadays. In this work, monoclinic Gd2O3:Er3+ nanoparticles, which possess up-conversion luminescence and down-conversion luminescence properties, were successfully synthesized by laser ablation in liquid (LAL) technique. Up-conversion luminescence and down-conversion luminescence of monoclinic Gd2O3:Er3+ nanoparticles were got under the excitation of 980 nm and 379 nm, respectively. In addition, tunable luminescence was got. Furthermore, the cytotoxicity of the nanoparticles is low and the fluorescence of the nanoparticles in cell is also strong enough. The results indicate that the Gd2O3:Er3+ nanoparticles synthesized by LAL technique are promising candidates for bio-imaging or other fields that require controllable fluorescence.
Multifunctional NiO@Gd 2 O 3 :Er 3+ ,Yb 3+ hollow nanocomposites (NCs) with mesoporous, upconversion (UC) luminescent and magnetic properties are synthesized by a facile hydrothermal process. Transmission electron microscope (TEM) and scanning electron microscope (SEM) images reveal that the samples have hollow structures with double shells of UC layer and magnetic layer. N 2 adsorption/desorption isotherm analysis shows the samples have large surface area of 29.052 m 2 /g and typical mesoporous structure. Multicolored UC luminescence at 521 nm, 541 nm and 654 nm are obtained under 980 nm laser excitation. In addition, the measured magnetic hysteresis loops indicate the samples exhibit high superparamagnetic behavior (15.8 emu/g). These multifunctional NCs have potential applications in the field of fluorescence probe, targeted therapy, magnetic separation, etc.
In this paper, a composite material GQDs/Gd 2 O 3 :Er 3+ /TiO 2 , was prepared by polyol method and hydrothermal method to improve the catalytic performance of TiO 2 . The composite material is analyzed by XRD, SEM, TEM, XPS, RAMAN, UV–Vis and PEC electrochemical test, combined the DFT theoretical calculation simulation. SEM and TEM results show that spherical GQDs/Gd 2 O 3 :Er 3+ nanoparticles are covered on the surface of TiO 2 nanorods. UV–Vis absorption spectra indicates that GQDs/Gd 2 O 3 :Er 3+ broadens the wavelength range of TiO 2 in the wavelength range of 400–1000 nm. The photocurrent density and the applied bias light-electroconversion efficiency of the electrodes of GQDs/Gd 2 O 3 :Er 3+ /TiO 2 is 3.47 times and 7.6 times as that of pure TiO 2 , respectively. DFT calculations reveal that the band width of GQDs/Gd 2 O 3 :Er 3+ /TiO 2 is decreased by 2.647 eV compared to pure TiO 2 , resulting in an easier transition of electrons from valence band (VB) to conduction band (CB). Photocatalytic tests show that the degradating efficiency of methylene blue (MB) by GQDs can reach 68.52 %, which is higher than that of pure TiO 2 (61.68 %).
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