Amorphous non-doped, iodine- and tin-doped Sb2S3 nanoparticles were prepared via the hot-injection method. HRTEM of amorphous undoped and doped samples revealed the formation of spherical ...nanoparticles of 20–50 nm diameter aggregated into clusters in the size of 100–200 nm. EDX analysis indicated the presence of desired elements in all observed samples. The bandgaps of non-doped and doped samples were determined from the reflectance spectra, and variations of the bandgaps, even small ones, are insufficient indications of doping. These uncertainties are further clarified by investigating crystalline undoped and doped samples in addition to the amorphous ones. XRPD results of the amorphous samples confirmed the amorphous structure, while Le Bail refinements of the crystalline samples show well-defined peaks from only the Sb2S3 phase, indicating a successful doping process. XPS measurements revealed that the phase of the undoped sample is free of impurities and that 3 d peaks of iodine and tin in the doped samples are present. The XPS valence bands shifted towards higher (I) or lower (Sn) binding energies compared to the undoped samples for both amorphous and crystalline samples, which is an additional support that incorporation of dopant ions in the Sb2S3 lattice took place.
Sb2S3 has excellent potential in the form of films, nanoparticles, and nanostructures, and has outstanding optoelectrical properties that allow its function as absorber material in SC devices. A few years ago, we reported Cu and Se doped Sb2S3 nanoparticles and applied them to different SC devices. In this paper, we develop new and improved synthesized nanomaterial based on non-doped and Sn and I doped Sb2S3 semiconductor for application. Display omitted
Nanopowders of up-conversion SrGd2O4 orthorhombic (Pnma) phase co-doped with different Yb3+ (1, 2.5 and 5 at%) and constant Er3+ (0.5 at%) ions were successfully prepared via sol-gel assisted ...combustion. Rietveld refinement indicated unit cell lattice parameters increase with Yb3+ and Er3+ ions doping. Scanning transmission electron microscopy with corresponding energy-dispersive X-ray spectroscopy revealed that obtained powders are composed of agglomerated nanoparticles that have a uniform distribution of all constituting elements. Photoluminescence measurements implied intensification of the up-conversion (UC) emission in the visible part of spectrum with the increase of Yb3+ content, which is followed by a significant change in the green to red ratio. Two-photon UC processes are established as a result of Er3+ f-f electronic transitions: green emission at 523 and 551 nm (2H11/2, 4S3/2 → 4I15/2) as well as a red emission at 661 nm (4F9/2 → 4I15/2). The highest value of absolute quantum yield of 0.055% is determined for SrGd2O4 nanoparticles doped with 0.5 at% of Er3+ and co-doped with 5 at% of Yb3+ (λexc = 976 nm, power density 200 W/cm2).
•Up-conversion SrGd2O4:Yb, Er nanoparticles are prepared via sol-gel combustion.•Random distribution of Yb over two Gd sites in Pnma structure is determined.•Two photon up-conversion (green and red) is affected by the Yb/Er ratio.•Quantum yield of 0.055 % is measured for radiation densities over 200 W/cm2.
Catalytic materials are the greatest challenge for the commercial application of water electrolysis (WEs) and fuel cells (FCs) as clean energy technologies. There is a need to find an alternative to ...expensive and unavailable platinum group metal (PGM) catalysts. This study aimed to reduce the cost of PGM materials by replacing Ru with RuO
2
and lowering the amount of RuO
2
by adding abundant and multifunctional ZnO. A ZnO@RuO
2
composite in a 10:1 molar ratio was synthesized by microwave processing of a precipitate as a green, low-cost, and fast method, and then annealed at 300°C and 600°C to improve the catalytic properties. The physicochemical properties of the ZnO@RuO
2
composites were investigated by X-ray powder diffraction (XRD), Raman and Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The electrochemical activity of the samples was investigated by linear sweep voltammetry in acidic and alkaline electrolytes. We observed good bifunctional catalytic activity of the ZnO@RuO
2
composites toward HER and OER in both electrolytes. The improved bifunctional catalytic activity of the ZnO@RuO
2
composite by annealing was discussed and attributed to the reduced number of bulk oxygen vacancies and the increased number of established heterojunctions.
In this manuscript, down-conversion nanopowders of SrGd2O4 doped with
different concentrations of either Dy3+ or Sm3+ ions were examined in
detail. All samples were prepared via glycine-assisted ...combustion method,
primarily burned at 500?C for 1.5 h and additionally calcined at 1000?C for
2 h, at ambient room temperature. The XRD analysis showed that all samples
crystallize as single phase and the orthorhombic lattice SrGd2O4. TEM
analysis determined high degree of crystallinity of samples with grain size
of approximately 200 nm for Dy3+ doped and 150 nm for Sm3+ doped SrGd2O4.
For both samples SAED confirmed that diffraction rings correspond to the hkl
plane indices of SrGd2O4, while EDS confirmed presence of Dy in crystal
structure. Results of luminescent characterization demonstrated all
appropriate emission peaks related to either Dy3+ or Sm3+ dopant ions.
Investigation of dopant concentration revealed that the lowest values of
both dopants have the most prominent emission peaks, while coordinates
obtained from the CIE diagram showed emission shifting with the change of
concentration.
The present work was focused on doping of 1% and 5% both of Nd2O3 and Sm2O3 in geopolymer gels. One of the main goals was to determine the influence of the behavior of Nd and Sm as dopants and ...structural nanoparticles changes of the final geopolymer formed. It is shown that the disorder formed by alkali activation of metakaolin can accommodate the rare earth cations Nd3+ and Sm3+ into their aluminosilicate framework structure. The main geopolymerization product identified in gels is Al-rich (Na)-AS-H gel comprising Al and Si in tetrahedral coordination. Na+ ions were balancing the negative charge resulting from Al3+ in tetrahedral coordination. The changes in the structures of the final product (geopolymer/Nd2O3; Sm2O3), has been characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analysis with energy dispersive spectrometry (EDS). Nucleation at the seed surfaces leads to the formation of phase-separated gels from rare earth phase early in the reaction process. It is confirmed that Nd and Sm have been shown to form unstable hydroxides Nd(OH)3 and Sm(OH)3 that are in equilibrium with the corresponding oxides.
In this manuscript, down-conversion nanopowders of SrGd204 doped with different concentrations of either Dy3+ or Sm3+ ions were examined in detail. All samples were prepared via glycine-assisted ...combustion method, primarily burned at 500°C for 1.5 h and additionally calcined at 1000°C for 2 h, at ambient room temperature. The XRD analysis showed that all samples crystallize as single phase and the orthorhombic lattice SrGd204. TEM analysis determined high degree of crystallinity of samples with grain size of approximately 200 nm for Dy3+ doped and 150 nm for Sm3+ doped SrGd204. For both samples SAED confirmed that diffraction rings correspond to the hkl plane indices of SrGd204, while EDS confirmed presence of Dy in crystal structure. Results of luminescent characterization demonstrated all appropriate emission peaks related to either Dy3+ or Sm3+ dopant ions. Investigation of dopant concentration revealed that the lowest values of both dopants have the most prominent emission peaks, while coordinates obtained from the CIE diagram showed emission shifting with the change of concentration.
Catalytic materials are the greatest challenge for the commercial application of water electrolysis (WEs) and fuel cells (FCs) as clean energy technologies. There is a need to find an alternative to ...expensive and unavailable platinum group metal (PGM) catalysts. This study aimed to reduce the cost of PGM materials by replacing Ru with RuO
and lowering the amount of RuO
by adding abundant and multifunctional ZnO. A ZnO@RuO
composite in a 10:1 molar ratio was synthesized by microwave processing of a precipitate as a green, low-cost, and fast method, and then annealed at 300°C and 600°C to improve the catalytic properties. The physicochemical properties of the ZnO@RuO
composites were investigated by X-ray powder diffraction (XRD), Raman and Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. The electrochemical activity of the samples was investigated by linear sweep voltammetry in acidic and alkaline electrolytes. We observed good bifunctional catalytic activity of the ZnO@RuO
composites toward HER and OER in both electrolytes. The improved bifunctional catalytic activity of the ZnO@RuO
composite by annealing was discussed and attributed to the reduced number of bulk oxygen vacancies and the increased number of established heterojunctions.
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