Gallium Hydroxide Research Articles

Gallium hydroxide coated Ti3C2Tx MXene for high-performance asymmetric supercapacitor

Ti3C2Tx MXenes have emerged as promising candidates for energy storage applications due to their two-dimensional structure, metallic conductivity, tunable surface functionalities, and intrinsic pseudocapacitive charge storage. This study explores the hydrothermal synthesis of GaOOH/Ti3C2Tx composites using gallium nitrate as the gallium precursor. The incorporation of GaOOH not only expands the interlayer spacing of Ti3C2Tx, facilitating more efficient electrolyte ion migration, but also enhances the material's energy storage capacity by introducing additional active sites and augmenting pseudocapacitance. As an electrode material in supercapacitors, GaOOH/Ti3C2Tx composites, prepared with a 0.06 M gallium source concentration, achieve a remarkable specific capacitance of 542.1 F·g−1, surpassing that of pristine Ti3C2Tx (305 F·g−1), with a minimal degradation of only 3.4 % after 5000 charge-discharge cycles. This research offers valuable insights into the electrochemical behavior of GaOOH/Ti3C2Tx composites and highlights the role of GaOOH in enhancing the performance of these materials. The results underscore the potential of combining metal hydroxides with MXenes for advanced supercapacitor applications.

Microstructure and properties of Cu-doped β-Ga2O3 rod prepared with liquid metallic gallium

One-dimensional β-Ga2O3 is expected for potential applications in electronics, sensors, and optoelectronics. Gallium hydroxide (GaO(OH)) with different Cu doping was prepared via the hydrothermal method using liquid metallic gallium and copper chloride dihydrate (CuCl2·2H2O) as the starting materials. The material was then transformed to β-Ga2O3 after calcination at 800 °C. SEM images reveal that the obtained powders are well dispersed and have a uniform rod morphology with a length of 13–14 μm and a width of approximately 500 nm. The addition of Cu ion significantly improves the surface morphology of the rod and effectively inhibits the generation of intrinsic oxygen vacancies. And the relative Fermi energy level of Cu-doped β-Ga2O3 undergoes a notable shift from 2.81 eV to 1.25 eV, suggesting the formation of p-type conductivity. Meanwhile, the PL spectra of the Cu-doped samples exhibit emission peaks in the red wavelength range, which is expected for new applications.

Ultrahigh purity beta gallium oxide microstructures

Ultrahigh purity gallium oxide (Ga 2 O 3 ) microstructures were synthesized via hydrothermal method using gallium nitrate hydrate and ammonium hydroxide to synthesize gallium hydroxide, followed by calcination at a 1000 °C. Scanning electron microscopy revealed that following calcination, the material showed a large number of microparticles with lengths of ≤1 μm and diameters of 250–350 nm. Energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy analyses indicated the high purity and near-stoichiometric composition of the material. The results also confirm the formation of β-phase Ga 2 O 3 with high crystallinity.

Role of humidity in oxidation of ultrathin GaSe

The oxidation mechanisms of exfoliated Gallium Selenide (GaSe) are strongly influenced by humidity. We have observed that the presence of water molecules leads to formation of Ga2O3, SeO2, and Se via sequence of intermediate reactions which include generation of aqueous solution of selenic acid. Raman spectra of GaSe flakes undergoing oxidation in a humidity-controlled environment reveal formation of selenic acid-related species causing Raman scattering signal in the regions around 830 cm−1 and around 1230 cm−1. This observation sheds light on the path of chemical reactions, going via an intermediate stage of formation of gallium hydroxide and selenium oxide-water complexes with further decompositions of these compounds to Ga2O3, SeO2, and amorphous selenium.

Synthesis, crystal structure and optical properties of Me(OH)(HCOO)2 (Me = Al, Ga)

Aluminium and gallium hydroxide diformates have been synthesized. Both compounds exhibit similar monoclinic lattice, according to the X-ray, neutron diffraction and IR spectroscopy data. Their samples possess a bright light-blue emission under UV excitation. The origin of intrinsic emission is elucidated by means of DFT calculations.

Water-soluble metalloporphyrinates with excellent photo-induced anticancer activity resulting from high tumor accumulation

To develop a water-soluble and tumor-targeted photosensitizer for photodynamic therapy (PDT), a porphyrin framework containing the metal ion gallium(III) was combined with platinum(II)-based groups to produce two new pentacationic metalloporphyrinates, Ga-4cisPtTPyP (5,10,15,20-tetrakis{cis-diammine-chloro-platinum(II)}(4-pyridyl)-porphyrinato gallium(III) hydroxide tetranitrate) and Ga-4transPtTPyP (5,10,15,20-tetrakis{trans-diammine-chloro-platinum(II)} (4-pyridyl)-porphyrinato gallium(III) hydroxide tetranitrate). Both complexes exhibited high singlet oxygen quantum yields (Φ∆) and remarkable photocytotoxicity with appreciable phototoxic indexes (PIs). In particular, Ga-4cisPtTPyP showed a low IC50 value (Colon 26: 0.12μM; Sarcoma 180: 0.08μM) under illumination and its PI up to 1000. With outstanding tumor accumulation (tumor/muscle ratio>9), Ga-4cisPtTPyP almost completely inhibited tumor growth over two weeks in an in vivo PDT assay. These results imply that Ga-4cisPtTPyP could be a promising anticancer agent for use in PDT.

Characterization of spin-coated gallium oxide films and application as surface passivation layer on silicon

Gallium oxide films have shown a great potential as passivation layers on silicon solar cells. In this work, we employed the spin-coating method to form gallium oxide films on p-type silicon substrate as a surface passivation layer. The dependences of the structure and the surface passivation effect of the gallium oxide films on the annealing temperatures were investigated. Both Ga 3d and 2p 3/2 regions were also measured by X-ray photoelectron spectroscopy analysis to obtain the complementary information on the composition of the Ga2O3 films (versus depth). In addition, the Qeff polarity change and a C-V clockwise hysteresis of Ga2O3 passivated samples were also discussed in this study. The gallium oxide films underwent an amorphous-to-crystalline phase transformations as the annealing temperature was increased above 550 °C. With an annealing temperature increased from 450 to 850 °C, the thickness of an interfacial silicon oxide layer increased from 2 to 7.4 nm; the interface state density, Dit, decreased from 4.21 × 1011 to 1.53 × 1011 eV−1 cm−2 and the effective oxide charge density, Qeff, changed from −3.7 × 1010 to 1.1 × 1011 cm−2 respectively. The Dit dominated the films passivation effect of the gallium oxide films with increasing annealing temperatures. The residual gallium hydroxide can act as a hydrogen reservoir for hydrogen diffusion and the interface hydrogenation play an important role in the Dit decrease.

Effect of post-deposition annealing on low temperature metalorganic chemical vapor deposited gallium oxide related materials

Low temperature metalorganic chemical vapor deposition using trimethylgallium and water was investigated. The surface morphology of the film was almost flat at a deposition temperature below 182°C. This flat film was a mixture of nanocrystalline and amorphous phase. The film deposited at a temperature of 272°C resulted in a nanowire structure. X-ray diffraction measurements revealed that the nanowire film was a mixture of gallium hydroxide, gallium oxyhydroxide, and gallium tohdite or gallium oxide. We also found that post-deposition annealing above 600°C significantly changed the crystal structure of the both flat and nanowire films. Monoclinic gallium oxide phase was dominant after the post-deposition annealing above 600°C.

Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR spectroscopy

Ordering of gallium(III) in a series of magnesium gallium (MgGa) layered double hydroxides (LDHs), [Mg1−xGax(OH)2(NO3)x·yH2O] was investigated using solid-state 1H and 71Ga NMR spectroscopy as well as powder X-ray diffraction. Three different proton environments from Mg3OH, Mg2GaOH and intergallery water molecules were assigned and quantified using {1H,71Ga} HETCOR and 1H MAS NMR. A single 71Ga site originating from the unique Ga site in the MgGa LDH׳s was observed in 71Ga MAS and 3QMAS NMR spectra. Both 1H MAS NMR spectra recorded at 21.1T (900MHz) and elemental analysis show that the synthesized MgGa LDH׳s had a lower Mg:Ga ratio than that of the starting reactant solution. The origin of this is the formation of soluble [Ga(OH)4]− complexes formed during synthesis, and not due to formation of insoluble gallium (oxy)hydroxides. No sign of GaOGa connectivities or defects were detected for the MgGa LDH׳s.

Compound-induced changes in thermal, structural and optical properties of indium–gallium–zinc oxides prepared by sol–gel method

In this study, IZO/IGZO powders and films of different composition ratios were fabricated by sol–gel method. The influences of the composition ratio on the decomposition temperature, crystallization behavior, structural and optical properties of multi-component oxides were thoroughly examined. Thermogravimetric/differential scanning calorimetric results revealed that in contrast to zinc and indium oxides, the high crystallization temperature and low crystallinity of gallium oxide were attributed to the high dehydroxylation temperature of gallium hydroxide, which led to the high decomposition and crystallization temperatures of IGZO compound. The XRD analysis of the IGZO films confirmed that the addition of Ga amount made the films turn into amorphous easily. However, TEM analysis suggested that the IZO film (In:Zn = 1:2) and the IGZO (In:Ga:Zn = 1:1:1) film consisted of short-range-order nanostructure although the selected area diffraction of both samples indicated that they are amorphous. The transmittance measurements agreed well with the XRD results; that is, the band gaps of the IZO/IGZO films obviously depend on the composition ratio and are closely related to the change of the structural properties.

Variable Coordination Modes of Potentially Tetradentate Phosphino‐ and Arsinoarylthiolato Ligands Derived from E(2‐SHC6H4)3 (E = P, As) in Gallium(III) Complexes

AbstractP(2‐SHC6H4)3 (PS3H3) reacts with GaMe3 (1:1) to give GaMe{P(2‐SC6H4)2(2‐SHC6H4)‐κ3S,S′,P} (1), which could be deprotonated with NEt3 to give [NEt3H][GaMe{P(2‐SC6H4)3‐κ3S,S′,P}] (2). The 1:2 reaction of E(2‐SHC6H4)3 [E = P (PS3H3), As (AsS3H3)] with GaMe3 gave the dinuclear complexes GaMe{E(2‐SC6H4)2(2‐S{GaMe2(THF)}C6H4)‐κ3S,S′,E} [E = P (3), As (4)]. Serendipitous hydrolysis of 4 resulted in small amounts of the hexanuclear gallium hydroxide complex cyclo‐{GaMe(μ‐OH)}6{As(2‐SC6H4)3‐κS,S′,S′′}2 (5). Complexes 1–4 were fully characterized, complexes 2–5 also by X‐ray crystallography.

水酸化ガリウム共沈濃縮-ICP-AESによる海水中の希土類元素の定量

水酸化ガリウム共沈濃縮-ICP-AESによる海水中の希土類元素の定量

Lanthanide-Ion-Assisted Structural Collapse of Layered GaOOH Lattice

GaOOH nanorods were prepared by hydrolysis of Ga(NO(3))(3)·xH(2)O by urea at ~100 °C in the presence of different amounts of lanthanide ions like Eu(3+), Tb(3+), and Dy(3+). On the basis of X-ray diffraction and vibrational studies, it is confirmed that layered structure of GaOOH collapses even when very small amounts of lanthanide ions (1 atom % and more) are present in the reaction medium during the synthesis of GaOOH nanorods. The incorporation of lanthanide ions at the interlayer spacing of the GaOOH lattice, followed by its reaction with OH groups that connect the layers containing edge-shared GaO(6) in GaOOH, is the reason for the collapse of the layered structure and associated amorphization. This leads to the formation of finely mixed hydroxides of lanthanide and gallium ions. These results are further confirmed by steady-state luminescence and excited-state lifetime measurements carried out on the samples. The morphology of the nanorods is maintained upon heat treatment at high temperatures like 500 and 900 °C, and during this process, the finely mixed lanthanide and gallium hydroxides facilitate diffusion of lanthanide ions into the Ga(2)O(3) lattice, as revealed by the existence of strong energy transfer with an efficiency of more than 90% between the host and lanthanide ions.

Comparison of different phosphorus-containing ligands complexing 68Ga for PET-imaging of bone metabolism

Abstract 99mTc-phosphonate structures are well established tracers for bone tumour imaging. Our objective was to investigate different 68Ga-labelled phosphonate ligands concerning labelling kinetics, binding to hydroxyapatite and bone imaging using μ-PET. Seven macrocyclic phosphorus-containing ligands and EDTMP were labelled in nanomolar scale with n.c.a. 68Ga in Na-HEPES buffer at pH∼4. Except for DOTP, all ligands were labelled with >92% yield. Binding of the 68Ga-ligand complexes on hydroxyapatite was analysed to evaluate the effect of the number of the phosphorus acid groups on adsorption parameters. Adsorption of 68Ga-EDTMP and 68Ga-DOTP was >83%. For the 68Ga-NOTA-phosphonates an increasing binding with increasing number of phosphonate groups was observed but was still lower than 68Ga-DOTP and 68Ga-EDTMP. μ-PET studies in vivo were performed with 68Ga-EDTMP and 68Ga-DOTP with Wistar rats. While 68Ga-EDTMP-PET showed uptake on bone structures, an excess amount of the ligand (>1.5 mg EDTMP/kg body weight) had to be used, otherwise the 68Ga3+ is released from the complex and forms gallium hydroxide or it is transchelated to 68Ga-transferrin. As a result, the main focus of further phosphonate structures has to be on complex formation in high radiochemical yields with macrocyclic ligands with phosphonate groups that are not required for complexing 68Ga.

Etching of GaAs(100) with Aqueous Ammonia Solution: A Synchrotron-Photoemission Spectroscopy Study

Etching of the GaAs(100) surface with aqueous ammonia solution is studied by highly surface-sensitive synchrotron-radiation photoemission spectroscopy. It is shown that such treatment effectively removes the native oxide layer leaving the surface covered with elemental arsenic, as well as arsenic hydroxides AsOH and As(OH)3, gallium hydroxide GaOH, and gallium suboxide GaxO. After annealing of the surface at 500 °C, the arsenic and gallium hydroxides disappear, while the excess arsenic is dimerized. The residual carbon contamination prevents disappearance of gallium hydroxide and hinders dimerization of excess arsenic on annealing. Rinsing the etched surface with 2-propanol instead of water prior to annealing results in considerable reduction of carbon contamination after annealing.

Dipeptide-assisted growth of uniform gallium oxohydroxide spindles

The catalytic dipeptide His–Ser was used as an additive in mineralizing gallium ions to form GaOOH, a solid precursor of Ga 2O 3. This dipeptide was chosen to mimic the enzyme structure of silicatein, similar to the well-known catalytic triad of chymotrypsin. The dipeptide promoted formation of spindle-structured GaOOH under acidic conditions by behaving as a heterogeneous nucleation seed. In contrast, no well-defined, structured gallium species were produced in the absence of dipeptide. The catalytic function of the dipeptide was most pronounced at pH values in the range 3–5, which are lower than the pKa of imidazole in the His side chain. These results suggest that the catalytic role of dipeptide influences the gallium hydroxide conversion and growth. This study suggests that a designed peptide with active functionality can be further exploited to produce inorganic compounds with controlled nucleation and growth.

Wet Etching of GaAs(100) in Acidic and Basic Solutions: A Synchrotron−Photoemission Spectroscopy Study

The interaction of the oxide-free GaAs(100) surface with acidic (HCl + 2-propanol) and basic (aqueous NH3) solutions is studied by synchrotron−photoemission spectroscopy. It is found that both solutions attack mostly surface gallium atoms and form weakly soluble gallium chlorides and soluble gallium hydroxides, respectively. Thereby, Ga−As bonds at the surface are broken, and elemental arsenic is left behind on the GaAs surface. In addition, adsorbed 2-propanol molecules are observed on etching with HCl + 2-propanol solution, but no adsorbed water molecules are detected on etching with aqueous ammonia solution.

Optical properties of a ‐plane GaN strained by photo‐chemically grown gallium hydroxide

AbstractWe report the observation of green emission centered at 500nm, accompanied with luminescence enhancement and spectral blue shift (∼31meV) in the bandedge emission from a ‐plane grown gallium nitride (GaN) passivated with gallium hydroxide (GaOOH). From study of the photo‐current response and polarization‐resolved low‐temperature micro‐photoluminescence (μ ‐PL) we resolved an evolution of gain competition process between the green and the UV emission bands. By dissolving the oxide we recover the emission characteristics of the as‐grown a ‐GaN. These observations can be ascribed to a formation of compressively‐strained a ‐GaN due to a coherently grown GaOOH atop layer. The latter is responsible for the spectral blue shift and the generation of acceptor like deep‐levels causing the green‐band transition in the emission and photo‐current response. Enhancement of bandedge emission from the oxide covered a ‐GaN is due to the GaOOH surface passivation effect which was prepared by the photo‐enhance wet oxidation method. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Quantitative Adsorption and Local Structures of Gallium(III) at the Water-α-FeOOH Interface

The adsorption of Ga(III) at the water-alpha-FeOOH (goethite) interface has been investigated by means of quantitative adsorption experiments, extended X-ray absorption fine structure (EXAFS) spectroscopy, and surface complexation modeling. Under the conditions studied, pH range 3-11 and surface coverages of 0.9-3.2 micromol/m2, Ga(III) was found to adsorb strongly to alpha-FeOOH, and the surface species were more resistant toward hydrolysis and formation of soluble Ga(OH)4- than either solid gallium hydroxides or soluble polynuclear complexes. The EXAFS measurements revealed the presence of octahedral Ga(III) complexes at the water-alpha-FeOOH interface, with practically no structural variations as a function of pH or total gallium concentration. Analysis of the first coordination shell required an anharmonic model indicating a distorted geometry of the GaO6 octahedra, with mean Ga-O distances at 1.96-1.98 angstroms. A method based on the continuous Cauchy wavelet transforms (CCWT) was used to identify backscattering atoms in the higher coordination shells. This analysis indicated predominately Fe backscattering, and the quantitative data fitting resulted in three Ga-Fe paths at 3.05, 3.2, and 3.55 angstroms, which correspond to two edge-sharing and one corner-sharing linkage, respectively. The collective results from EXAFS spectroscopy showed that Ga(III) adsorbs to Fe equivalent sites at the surface alpha-FeOOH as an extension of the rows of Fe octahedra in the bulk structure. This interpretation was further corroborated by a Ga-Fe-Fe multiple scattering path at 6.13 angstroms. The quantitative adsorption and proton data were modeled using a surface complexation formalism based on a 1 pK(a) constant capacitance model. In agreement with the EXAFS results, the model obtained included one predominating surface complex with the stoichiometry [triple bond]FeOGa(OH)2(-0.5) and the stability constant log beta(intr.) = -2.55 +/- 0.04 ([triple bond]FeOH(-0.5) + Ga3+ + 2H2O <--> [triple bond]FeOGa(OH)2(-0.5) + 3H+).

Tetra-tert-Butyl-di-m-Hydroxo Digallium(III) and 1,12-Diaza-3,4:9,10-Dibenzo-5,8-Dioxo-cyclo-Pentadecane. Structure and Isomers of the Coordination Compound

Tri-t-butylgallium has been reacted with the macrocycle 1,12-diaza-3,4:9,10-dibenzo-5,8-dioxocyclopentadecane which could be a potential ligand for gallium(III). A reaction product was analyzed and single crystal X-ray diffraction experiments showed that it consisted of the cyclic dimer of di-t-butylgallium-hydroxide hydrogen bonded to the macrocycle. Without a co-crystallized organic molecule di-t-butylgallium hydroxide crystallizes as a trimer. Density functional calculations have been used to predict the structures and the total energies for the monomer, dimer, trimer, and tetramer of dimethylgallium hydroxide in order to provide a basis for the understanding of oligomer population for the dimethylgallium hydroxides. Force field calculations are shown to be able to produce a similar strain energy difference for dimer, trimer, and tetramer forms of (CH3)2Ga(OH) and this method can economically be used for larger alkyl groups. The force field computations show that the trimeric di-t-butyl gallium(III) hydroxide is much more stable than the dimeric form which therefore must owe its existence to the association with the hydrogen-bonded macrocycle.