Template-Free Synthesis of Highly Uniform α-GaOOH Spindles and Conversion to α-Ga₂O₃ and β-Ga₂O₃

Abstract

Monodispersed single crystalline R-GaOOH spindles have been prepared via a simple wet-chemical route at 60 °C, in which GaCl 3 was used as the gallium source and ammonia as the alkali. The R-GaOOH spindles obtained at pH values of 10.0 and 11.0 have a hierarchical layered nanostructure and are comprised of many nanoplatelets. The investigation of the products formed at early growth stages indicates that the spindles are formed by a self-assembly process via oriented attachment. During this process, the pH value and the ammonia molecule have great influence on the morphology of the final products. Smooth prism-like R-GaOOH crystals were obtained at a lower pH value of 8.0 when ammonia was used or when ammonia was replaced by ethylenediamine at pH values of 8.0 and 10.0. The single-phase R-Ga 2 O 3 and β-Ga 2 O 3 spindles can be obtained by thermal treatment of the R-GaOOH spindles at 600 and 900 °C, respectively. The morphological characteristics of the pristine R-GaOOH spindles are well maintained in the oxide products in terms of good dispersion, size uniformity and layered nanostructure. The β-Ga 2 O 3 spindle product exhibits a strong blue luminescence emission under the excitation wavelength of 250 nm.

Cadmium Sulfide Quantum Dots Supported on Gallium and Indium Oxide for Visible‐Light‐Driven Hydrogen Evolution from Water

“…[27] The XRD patterns presented in Figure 1 [28] With the metal oxides as the support, the photocatalysts were constructed by the deposition of 1 wt % Pt (calculated) as the cocatalyst using a wet impregnation and chemical reduction method and 10 wt % of CdS QDs as the photosensitizer. The properties of the water-soluble CdS QDs have been described in detail in our earlier work.…”

Template-free synthesis, characterization, growth mechanism and photoluminescence property of Eu(OH)3 and Eu2O3 nanospindles

“…However, the synthetic strategy operating at this low temperature is also an energy-consuming route and a long aging time of 5 days is inevitably required. It is noted that the spindle-like nanocrystals with nanometer or micrometer size have been reported in recent years such as PbWO 4 [27], LnVO 4 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) [28], CeO 2 [29], YF 3 :Eu 3+ [5], CePO 4 :Tb 3+ [30], LnPO 4 [31], ␣-Ga 2 O 3 , and ␤-Ga 2 O 3 [32]. Most of these synthetic routes are complicated, energy-consuming and/or require surfactants and templates.…”

Dipeptide-assisted growth of uniform gallium oxohydroxide spindles

“…As a control, the GaOOH nanoparticles without dipeptides were synthesized by hydrothermal process according to the protocol present in Ref. [7]. The synthesized ones were used for the comparison in spectroscopic analyses.…”

“…Several approaches have been attempted to produce GaOOH nanoparticles with controlled shape and uniformity. For example, precipitation [6], hydrothermal treatment [7,8], a sonochemical reaction [9], and addition of chemicals as shape-controlling additives have been applied for shape-controlled GaOOH synthesis [10,11]. From these processes, GaOOH was obtained in complex shapes such as cylinders or multi-layers.…”