Ga Incorporation Research Articles

Dry Reforming of Methane (DRM) over Hydrotalcite-Based Ni-Ga/(Mg, Al)Ox Catalysts: Tailoring Ga Content for Improved Stability

Dry reforming of methane (DRM) is a promising way to convert methane and carbon dioxide into syngas, which can be further utilized to synthesize value-added chemicals. One of the main challenges for the DRM process is finding catalysts that are highly active and stable. This study explores the potential use of Ni-based catalysts modified by Ga. Different Ni-Ga/(Mg, Al)Ox catalysts, with various Ga/Ni molar ratios (0, 0.1, 0.3, 0.5, and 1), were synthesized by the co-precipitation method. The catalysts were tested for the DRM reaction to evaluate their activity and stability. The Ni/(Mg, Al)Ox and its Ga-modified Ni-Ga/(Mg, Al)Ox were characterized by N2 adsorption–desorption, Fourier Transform Infrared Spectroscopy (FTIR), H2-temperature-programmed reduction (TPR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Raman techniques. The test of catalytic activity, at 700 °C, 1 atm, GHSV of 42,000 mL/h/g, and a CH4: CO2 ratio of 1, revealed that Ga incorporation effectively enhanced the catalyst stability. Particularly, the Ni-Ga/(Mg, Al)Ox catalyst with Ga/Ni ratio of 0.3 exhibited the best catalytic performance, with CH4 and CO2 conversions of 66% and 74%, respectively, and an H2/CO ratio of 0.92. Furthermore, the CH4 and CO2 conversions increased from 34% and 46%, respectively, when testing at 600 °C, to 94% and 96% when the catalytic activity was operated at 850 °C. The best catalyst’s 20 h stream performance demonstrated its great stability. DFT analysis revealed an alteration in the electronic properties of nickel upon Ga incorporation, the d-band center of the Ga modified catalyst (Ga/Ni ratio of 0.3) shifted closer to the Fermi level, and a charge transfer from Ga to Ni atoms was observed. This research provides valuable insights into the development of Ga-modified catalysts and emphasizes their potential for efficient conversion of greenhouse gases into syngas.

Ga-doped spinel-typed Co-Al catalysts for CO2-assisted ethane dehydrogenation

A series of Ga-doped spinel-typed Co-Al catalysts were prepared via one-step evaporation-induced self-assembly (EISA) method. These catalysts present promising catalytic performance for CO2-assisted ethane dehydrogenation, which can be ascribed to the conjunction effect of cobalt and gallium species. The incorporation of Ga into the structure of Co-Al spinel has been recognized for enhancing CO2 conversion via reverse water-gas shift reaction, leading to a favorable equilibrium shift towards ethylene, along with an improved catalyst stability as a result of coexisting Boudouard reaction. Through X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS), NH3 and CO2 temperature-programmed desorption (TPD) characterizations, coordinatively unsaturated Co2+ and Ga3+ cations were identified as collaborative catalytic active sites, with gallium species taking the prominent role. These sites were closely associated with the formation of acid-base pairs on the catalyst surface, which were crucial for the adsorption and activation of the reactants.

Effect of Ga on microstructure and properties of Ag50CuSn12 and Al2O3/oxygen-free copper welds

The effects of Ga on the properties of Ag50CuSn12 and brazed joints were studied. The results show that Ga can reduce the melting temperature of the Ag50CuSn12 and improve its wettability. With the increase of Ga content, the spreading area of the solder increases first and then decreases. And the spreading area is the largest when the content of Ga is 3 wt%, which is 48% higher than that without Ga. Ga plays an important role in grain refinement of weld microstructure. The size of the block particles in the weld decreases accompanied by the increase of Ga. The fine strip grains increase is evenly distributed. The refinement effect is also the best when the Ga content is 3 wt%. For this reason, the shear strength of the brazed joint of Al2O3 and oxygen-free copper increases first and then decreases. When the Ga content is 3 wt%, the shear strength is the highest, which is 2.2 times that of the joint without Ga.The analysis suggests that the incorporation of Ga lowers the melting point of the solder, improves its oxidation resistance, and reduces its surface tension and viscosity, thereby enhancing its wettability and diffusivity. However, excessive Ga can hinder the solder's spread.

Flexible monolayer films of poly(lactic acid)/gallic acid for active food packaging: Preparation, characterization, and bioactive properties

AbstractThe design of eco‐friendly active food packaging systems based on biobased polymeric materials is a growing field of research because of the pressing concern for sustainable development. Herein, monolayer ternary thermoplastic films composed of poly(lactic acid) (PLA), gallic acid (GA, 2.5% w/w relative to PLA), and a plasticizer (poly(ethylene glycol) [PEG] or epoxidized linseed oil [ELO], 5.0 and 7.5% w/w relative to PLA) are prepared via melt‐mixing followed by compression molding. The ensuing plasticized and self‐standing PLA/GA films are translucent and have good mechanical properties (Young's modulus ~2 GPa) and welding performance. The incorporation of GA yields films with ultraviolet‐light barrier properties (transmittance below 40%, 200–400 nm), antioxidant capacity (radical scavenging activity above 94%), and antibacterial activity against the methicillin‐resistant strain of Staphylococcus aureus (minimum of 3‐log reduction colony forming units mL−1). These thermoplastic films are easily degradable via enzymatic degradation with proteinase K from Tritirachium album, reaching weight loss values of 100% after 9 days. The films plasticized with PEG present slightly better antibacterial action and enzymatic degradation, whereas those plasticized with ELO exhibit marginally higher surface hydrophobicity and thermal stability. Thus, the combination between PLA and GA yielded biobased films with bioactive properties that have potential for application in active food packaging.

Selective Hydrogenation of Diethyl Malonate to 1,3-Propanediol Over Ga-Promoted Cu/SiO2 Catalysts With Enhanced Activity and Stability.

Cu catalysts with different compositions and different Cu and promoter contents were prepared by precipitation-gel method and studied for the selective hydrogenation of syngas or biomass-based diethyl malonate (DEM) to valuable 1,3-propanediol (1,3-PDO). The Ga-promoted 70Cu6Ga/SiO2 catalyst was found to exhibit the highest catalytic performance, achieving 100 % DEM conversion and 76.6 % 1,3-PDO selectivity under reaction conditions of 160 °C and 8 MPa H2. The 70Cu6Ga/SiO2 bimetallic catalyst also presented obviously better stability than that of the monometallic 70Cu/SiO2 catalyst in a continuous flow reactor over 180 h time-on stream. Characterization results showed that the incorporation of Ga increased the interaction between Cu and Ga species, hindered the full reduction of Cu2+ species, and thus increased the proportion of Cu+ and the number of Lewis acidic sites on the catalyst surface. The synergistic effect between Cu0 and Cu+ enhanced the adsorption and activation of ester carbonyl groups and their subsequent hydrogenation, eventually contributed to the outstanding performances of the CuGa/SiO2 bimetallic catalysts.

Efficacy of Ga3+ ions on structural, biological and antimicrobial activity of mesoporous lithium silicate bioactive glasses for tissue engineering

Mesoporous bioactive glass nanoparticles (MBGNPs) containing therapeutic ions have shown significant promise in the realm of hard and soft tissue repair and regeneration, owing to their multifunctional biological properties. In this study, gallium-incorporated silica-based gallium incorporated MBGNPs (Ga-MBGNPs) with fixed amount of Li2O (8 mol %) were synthesized using an emulsion-assisted sol-gel method. The impact of Ga2O3 integration into the silicate glass network was evaluated by investigating the microtextural properties. The results confirmed the production of spherical-shaped, nano-sized, amorphous particles with an enhanced specific surface area and ordered hexagonal meso-porosity (10–20 nm) in the developed Ga-MBGNPs. The in vitro bioactivity, assessed through hydroxyapatite (HAp) layer formation in simulated body fluid (SBF), over varying time intervals (0, 1, 3, 7, 14 & 21 days), revealed pronounced formation of short rod-like carbonated HAp with increasing immersion time and Ga3+ content in all glasses. However, a delayed apatite formation was observed for composition-dependent Ga-4 and Ga-5 MBGs during the initial incubation periods (1, 3, and 7 days). Further, the presence of Li + ions along with Ga3+ enhanced the apatite deposition when compared with the only Ga3+ inclusion. Evaluation of degradation rate and pH values indicated enhanced apatite formation with lower Ga ion content, while a slight reduction was noted with higher Ga ion content, attributable to the presence of reactive Si–O–Si bonds. Furthermore, analysis using a Zeta potential analyzer confirmed the dispersibility and bioreactivity of all glass powders owing to their higher negative surface charge. Moreover, Ga-MBGNPs exhibited notable antimicrobial effects against both E. coli and S. aureus bacteria due to the release of Ga3+ ions. Overall, the findings suggest that the incorporation of Ga in MBGNPs renders them potential multifunctional candidates for expediting the healing of bone tissue injuries in biomedical applications.

Preparation and characterisation of silybin nanoemulsions based on complex emulsifiers: stability, in vitro release properties and antioxidant capacity

SummaryThe low solubility of Silybin (Slb) presents a significant obstacle to its further application. In this study, silybin nanoemulsion (Slb‐NE) stabilised by sodium aseinate/glycyrrhetinic acid (NaCas/GA) complex emulsifiers were prepared for effective delivery of Slb. When the NaCas:GA mass ratio was 1:1, Slb‐NE had small particle size (189 nm), low PDI (0.125), and high zeta potential (−27.27 mv). SEM, TEM, and FI‐IR studies indicated that the emulsion system was spherical and homogeneous, and Slb was successfully loaded into Slb‐NE without generating new chemical bonds. Furthermore, the complex emulsifiers improved the stability of Slb‐NE. In vitro release and antioxidant experiments showed that the incorporation of GA strengthened the sustained release and antioxidant capacity of Slb‐NE. NaCas/GA can be used as a natural and green complex emulsifiers for delivery of difficult‐to‐solve ingredients.

The Effect of Ga Incorporation in TiO2/SnO2 Nanoparticle‐Decorated Hierarchical ZSM‐5 Composite as Precious‐Metal‐Free Electrocatalysts for Oxygen Electro‐Reduction

AbstractThe slow nature of oxygen electro‐reduction has become a major obstacle in fuel cell commercialization. Researchers have recently focused on developing efficient electrocatalysts to address this issue. In this study, we investigated the catalytic activity of electrocatalysts based on metal‐incorporated zeolites. We prepared the zeolite socony mobil‐5 (ZSM‐5) zeolite samples hydrothermally and modified them to introduce mesopores and metal nanoparticles. The metal nanoparticles were supported on the hierarchical zeolite socony mobil‐5 (HZSM‐5) support materials by ion‐exchange process. Surface morphology analysis revealed that the pristine material had a smooth surface which became rough upon post‐modification of the material. Hierarchical zeolites showed large surface area and pore volume. The TiSn‐loaded‐HZSM‐5 demonstrated higher catalytic efficiency than other prepared electrocatalysts for ORR. The catalytic efficiency of the synthesized electrocatalysts was in the order TiSn‐HZSM‐5>GaSn‐HZSM‐5>TiGaSn‐HZSM‐5>TiGa‐HZSM‐5 with the onset potential of 0.86, 0.81, 0.80 and 0.78 V respectively. Catalysis is affected by the size, dispersion and electronic state of metal nanoparticles as observed by the catalytic efficiency of the trimetallic electrocatalysts which have low catalytic activity compared to bimetallic counterparts. Bimetallic hierarchical zeolites based electrocatalysts have great potential in catalysis, but there is still room for improvement.

Employing a chelating agent as electrolyte additive with synergistic effects yields highly reversible zinc metal anodes.

Aqueous zinc ion batteries (AZIBs) have attracted sustained attention owing to their intrinsic safety and low cost. Unfortunately, the dendrite growth and parasitic side reactions of metallic zinc anodes severely degrade the cycling stability of the batteries and limit the practical application of AZIBs. In this work, calcium gluconate (CG), a chelating agent, as a novel electrolyte additive was introduced to tackle the thorny issue of zinc anodes in a 2 M ZnSO4 electrolyte by the synergistic effects of gluconate (GA-) anions and Ca2+ cations. Experimental characterization and computational simulations confirmed that the incorporation of GA- can not only mitigate the precipitation of Ca2+ ions, but also affect the primary solvation shell (PSS) of Zn2+ and modulate the electrode/electrolyte interfacial reaction, thereby inhibiting side reactions. Besides, trace amounts of Ca2+ cations can preferentially adsorb on the surface of the zinc anode tip, forming an electrostatic shielding shell that guides the uniform deposition of zinc ions. The Zn//Zn symmetric cells achieved a remarkably prolonged cycling lifespan ranging from 174 h to 3745 h at 6.37 mA cm-2 and 2.88 mA h cm-2 with an ultrahigh cumulative plating capacity (CPC) of about 11 900 mA h cm-2. Even at a higher current density of 5 mA cm-2 and an areal specific capacity of 5 mA h cm-2, Zn//Zn cells with the CG additive cycled for 248 h, about 5 times better than that without the CG additive. These results pave the way for the exploitation of new electrolyte additives with synergistic effects in AZIBs.

Panning ideal In(Ga)As(P)/InGaP quantum dot structures for intermediate band solar cells

The In(Ga)As(P)/InGaP quantum dot (QD)system has been investigated for QD intermediate band solar cells. In order to obtain optical transition energies compatible with the ideal ones required for the device record performance, namely: 1.95 eV, 1.24 eV and 0.7 eV, first disordered InGaP with a bandgap of 1.91 eV as the barrier material has been obtained. Then InAs QDs nucleated at 490 °C, 1.32 MLs thick, covered by a 3–4 nm GaAs capping layer and In-flushed provided radiation emission in the energy interval between 1.15 eV and 1.35 eV, fully compatible with the ideal 1.24 eV. The 4 nm capped structures have been proven to exhibit a stronger PL emission at 1.24 eV. Nominal InAs QDs suffer a pronounced incorporation of Ga, a consequence of In/Ga intermixing at their capping layer and barrier interfaces. An As/P intermixing also takes place at the quantum dot—barrier interface. The encouraging results herald further improvement of QD intermediate band solar cell’s performance.

Quenching-driven advancements in functional properties of high-temperature lead-free Sc, Ga modified 0.67BiFeO3-0.33BaTiO3 relaxor ceramics

The processing method is one of the most important deciding factors in the fabrication of BiFeO3–BaTiO3 (BF-BT) based piezoceramics because of the Bi2O3 volatization. It significantly influences the functional properties, including the piezoelectric coefficients, dielectric properties, and microstructure. This study presents a significant advancement in the realm of high-temperature lead-free piezoelectric ceramics in terms of understanding effects of processing method on functional properties. In this light, a novel ceramic solid-solution, 0.67{Bi(Fe0.97Ga0.03)1-xScxO3}-0.33(BaTiO3) with x ≤ 0.07, incorporating Scandium (Sc) and Gallium (Ga) modifications, was meticulously designed and synthesized. Impact of two distinct sintering methods, namely air quenching (AQ) and closed sintering (CS) on the structure and properties of the developed materials are investigated. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analysis verified the formation of pure perovskite phases with successful incorporation of Sc and Ga into the 0.67BF-0.33BT lattice. The FTIR analysis revealed a sharp absorptive band in the 590-604 cm−1 range, corresponding to the signature of stretching and bending vibrations of (Ti/Fe)O6 octahedra. Rietveld structure refinement confirmed the coexistence of pseudocubic (Pm-3m) and rhombohedral (R3c) phases in AQ samples, with predominantly pseudocubic phase, while CS samples closely approximated the pseudocubic phase. The microstructure of the samples exhibits small average grain size distribution (<2 μm). Temperature-dependent dielectric measurements show strong frequency dispersion in the dielectric permittivity with broadened transition peaks. The ferroelectric studies reveal low Pr and Ec values. These observations suggest a ferroelectric relaxor-like behavior of the developed materials. Moreover, the permittivity peaks maxima (Tm) temperature corresponding to CS samples for 0.04<x < 0.07 is less than 390 °C at 10 Hz while it is above 400 °C for AQ samples. The results of our study reveal that AQ samples exhibit superior electrical and ferroelectric properties as compared to the CS samples. The AQ samples demonstrate improvements in Tm (>400 °C), d33(∼35 pC/N), Pr (∼4–11 μC/cm2), PS (∼8–21 μC/cm2), Ec (∼13–25 kV/cm) with reduced dielectric loss, and a better dielectric constant over a wide temperature range.

Light-trapping structures fabricated in situ for ultrathin III-V solar cells

Here, we describe a fully in situ method of fabricating light-scattering structures on III-V materials that generates a rough morphology via vapor phase etching and redeposition. Fully in situ methods support higher industrial throughput by utilizing the growth reactor to generate the light-trapping structures after device growth without removal from the reactor. We use HCl and PH3 to etch and redeposit scattering morphologies on Ga0.5In0.5P in a dynamic hydride vapor phase epitaxy (D-HVPE) reactor. We show that the addition of PH3 leads to redeposition during the vapor phase HCl etching of Ga0.5In0.5P and that HCl flow rate and time exposed to HCl-PH3 each independently cause a linear increase in the redeposited feature size, indicating that redeposition proceeds by island growth in a III-Cl-limited, hydride-enhanced HVPE regime. Auger electron spectroscopy and scanning transmission electron microscopy with energy dispersive spectroscopy (STEM-EDS) reveal redeposition to be highly Ga-rich GaInP, i.e., Ga(In)P. The Ga-rich nature of the redeposition results from the higher thermodynamic driving force for Ga incorporation than for In during HVPE growth and the difference in the volatility of the III-Cl etch products. The resulting morphologies have high broadband scattering, as determined by normal specular reflectance and integrating sphere measurements, indicating effectiveness as light-scattering structures. In a 270-nm-thick GaAs photovoltaic device with a textured back surface, we achieve a 4.9% increase in short circuit current density (JSC) without any loss in open-circuit voltage (VOC) relative to a planar control using only a 60 s in situ texturing treatment.

Branched-gallium phosphide nanowires seeded by palladium nanoparticles

Palladium nanoparticles were produced by a chemical reagent-free and versatile method called spark ablation with control over particle size and density. These nanoparticles were used as catalytic seed particles for gallium phosphide nanowire growth by metalorganic vapour-phase epitaxy. Controlled growth of GaP nanowires using significantly small Pd nanoparticles between 10 and 40 nm diameter was achieved by varying several growth parameters. Low V/III ratios below 2.0 promote higher Ga incorporation into the Pd nanoparticles. Moderate growth temperatures under 600 °C avoid kinking and undesirable GaP surface growth. In addition, a second batch of palladium nanoparticles of concentration up to 1000 particles μm−2 was deposited onto the GaP nanowires. Subsequently, three-dimensional nanostructures evolved, with branches growing along the surface of the GaP nanowires. The GaP nanowires revealed a zinc blende structure with multiple twinning and a PdGa phase at the tip of the nanowires and branches.

Compositional effects of Ga incorporation on electrical and dielectric parameters in Ge-Se-Sb-Ga thin films

In this paper, the existence of new selenium-rich chalcogenide glassy systems i.e. (Ge20Se80)90-xSb10Gax (x = 2, 4, 6 and 10 at %) had been reported. (Ge20Se80)90-xSb10Gax glassy systems were prepared using melt-quenching technique. Thin films of (Ge20Se80)90-xSb10Gax were prepared on properly cleaned glass substrates using vacuum evaporation technique. Planar geometry of indium (In) electrodes (electrode spacing 0.08 cm) was used for electrical measurements. The physical parameters – average number of constraints, cohesive energy, mean bond energy, average coordination number, heat of atomization, glass transitition temperature and lone pair electrons had been estimated. The high values for the lone pair electrons proves the investigated system to be a good glass former. The increasing values of cohesive energy, glass transition temperature and mean bond energy with the incorporation of Ga, reveal that Ge-Se-Sb-Ga glassy systems are thermally stable glasses. The current transport mechanisms had been studied within the temperature range 173–363 K. Thermionic emission dominated in the high temperature region above 333 K. Within the intermediate temperature range 273–333 K, thermally-assisted tunneling of the charge carriers through grain boundary potential as well as thermionic emission over grain boundary potential contributed to the conduction mechanism. Below 273 K, Mott’s hopping process dominated the conduction mechanism. Dielectric measurements had been examined within the temperature range 173–363 K and the frequency range 50 Hz–1 MHz. Dielectric constant as well as dielectric loss decreased as the frequency was increased and increased as the temperature was increased. Orientation polarization described the temperature-dependence and frequency-dependence of dielectric constant. Temperature-dependence and frequency-dependence of dielectric loss was explained by conduction loss as well as hopping of charger carriers. The ac conductivity agrees with the power law: ωs where s < 1. The present investigation of dielectric parameters could be explained in terms of correlated barrier hopping (CBH) model. Profound analysis of the physical, electrical and dielectric properties and their variation as a function of Ga-content suggest the utilization of these glasses in optoelectronic devices.

Unraveling the role of GaZrOx structure and oxygen vacancy in bifunctional catalyst for highly active and selective conversion of syngas into light olefins

The direct conversion of syngas to light olefins (STO) over metal oxide-zeolite (OX-ZEO) bifunctional catalyst has aroused wide interest. However, due to unmatched reaction temperature for CO conversion to oxygenated hydrocarbons over metal oxide (200–300 °C) and C−C coupling reaction over zeolite (350–450 °C), it is still a great challenge to achieve both high light olefins selectivity and high CO conversion; moreover, the reaction mechanism needs to be further studied. Herein, the Ga-Zr oxide is taken as a probe oxide to mix with SAPO-34 zeolite for STO. A high light olefins selectivity of 88.6% is achieved at an extremely high CO conversion of 51.6% with a stable activity for 200 h. The incorporation of Ga into ZrO2 generates the GaZrOx solid solution structure with abundant concentration of oxygen vacancy and hydroxy group, the strong synergetic effect between Ga and Zr in GaZrOx benefits the CO activation and CH3O* formation at high temperatures (280–430 °C), providing a compatible temperature match for C−C coupling over SAPO-34. The GaZrOx is a promising and potential catalyst for industrial application in direct conversion of syngas to olefins, aromatics, and liquid fuels.

Insights into the Efficiency Improvement for CZTSSe Solar Cells with over 12% Efficiency via Ga Incorporation

AbstractSuppressing the band tailing and nonradiative recombination caused by massive defects and defect clusters is crucial for mitigating open‐circuit voltage (Voc) deficit and improving the device performance of CZTSSe thin film solar cells. Cation substitution is one of the most commonly used strategies to address the above issues. The latest world record efficiency of 13.0% is obtained through this strategy (Ag substitution for Cu). Nevertheless, the importance of the approach to implementing metallic ion doping is easily overlooked by researchers. Here, different approaches are adopted to realize Ga doping and the differences in the efficacy and mechanism are thoroughly investigated. It is found that the secondary phase easily emerged when the physical‐based method is employed, and thus challenging to regulate the doping effect. In the case of the chemical‐based method, Ga doping can enlarge the depletion region widthand lower the defect activation energyand Urbach energy. Furthermore, GaSn defects located at grain boundaries can expand the energy band bending between GBs and grain interiors (GIs), thereby suppressing the deep defect states and nonradiative recombination. Consequently, power conversion efficiency as high as 12.12% with a Voc of 522 mV is achieved at 2% Ga doping.

Acceptor and compensating donor doping of single crystalline SnO (001) films grown by molecular beam epitaxy and its perspectives for optoelectronics and gas-sensing

(La and Ga)-doped tin monoxide [stannous oxide, tin (II) oxide, SnO] thin films were grown by plasma-assisted and suboxide molecular beam epitaxy with dopant concentrations ranging from ≈ 5 × 1018 to 2 × 1021 cm−3. In this concentration range, the incorporation of Ga into SnO was limited by the formation of secondary phases observed at 1.2 × 1021 cm−3 Ga, while the incorporation of La showed a lower solubility limit. Transport measurements on the doped samples reveal that Ga acts as an acceptor and La as a compensating donor. While Ga doping led to an increase in the hole concentration from 1 × 1018−1 × 1019 cm−3 for unintentionally doped (UID) SnO up to 5 × 1019 cm−3, La-concentrations well in excess of the UID acceptor concentration resulted in semi-insulating films without detectable n-type conductivity. Ab initio calculations qualitatively agree with our dopant assignment of Ga and La and further predict InSn to act as an acceptor as well as AlSn and BSn as donors. These results show the possibilities of controlling the hole concentration in p-type SnO, which can be useful for a range of optoelectronic and gas-sensing applications.

Rational design of Ga-substituted NaY zeolites with controllable acidity for remarkable carbonylation of methyl nitrite to dimethyl carbonate

Lack of high performance and stability catalysts remains a technical bottleneck for the industrialization of methyl nitrite (MN) carbonylation to dimethyl carbonate (DMC). Lewis acidity is crucial for catalytic performance in MN carbonylation reaction, but the regulation of Lewis acid sites and the effects of Lewis acid strength on catalytic performance have not been clarified. Thus, rational design of NaY zeolites with controllable acidity is an effective strategy to promote their catalytic performance. Herein, we substituted Ga for partial framework Al to produce a series of NaGaY-x (x = 0 ∼ 2) zeolites with different Ga content via direct hydrothermal method and applied in this reaction. The results showed that the Lewis acid strength increased upon an appropriate amount of Ga incorporation, thereby the electron density of Pd2+ could be regulated. The optimal electron density of Pd2+ promotes the carbon monoxide (CO) adsorption and activation, which contribute to the formation of the critical intermediate species *COOCH3. Eventually, the Ga-modified PdCu/NaY catalyst exhibited remarkable catalytic activity for MN carbonylation to DMC with the weight-time yields (WTYDMC) of 1251 g·kgcat−1·h−1, and the CO conversion to DMC (CCO) of 69.2 % as well as the DMC selectivity based on CO (SDMC/CO) up to 100 %. Our work paves the way to further understand the synergistic effect between Pd2+ and Lewis acid, assists in the development of high-performance MN carbonylation catalysts.

Vacuum Electrodeposition of Cu(In, Ga)Se2 Thin Films and Controlling the Ga Incorporation Route

The traditional electrochemical deposition process used to prepare Cu(In, Ga)Se2 (CIGS) thin films has inherent flaws, such as the tendency to produce low-conductivity Ga2O3 phase and internal defects. In this article, CIGS thin films were prepared under vacuum (3 kPa), and the mechanism of vacuum electrodeposition CIGS was illustrated. The route of Ga incorporation into the thin films could be controlled in a vacuum environment via inhibiting pH changes at the cathode region. Through the incorporation of a low-conductivity secondary phase, Ga2O3 was inhibited at 3 kPa, as shown by Raman and X-ray photoelectron spectroscopy. The preparation process used a higher current density and a lower diffusion impedance and charge transfer impedance. The films that were produced had larger particle sizes.

Low temperature selective growth of Ga-doped and Ga–B co-doped germanium source/drain for PMOS devices

The peculiarities and physical properties of gallium-doped (Ge:Ga) and gallium and boron co-doped germanium (Ge:Ga:B) epilayers grown at low temperature (320 °C) by chemical vapor deposition, are investigated and benchmarked against their boron-doped (Ge:B) counterpart. Ge:Ga films with resistivities <0.3 mΩ.cm < 0.3 mΩ.cm are demonstrated, outperforming Ge:B prepared with a similar method. A selective Ge:Ga growth process based on a cyclic deposition and etch routine is developed and applied to fin structures. Full process selectivity towards nitride and oxide surfaces is demonstrated. Ga incorporation is, however, reduced compared to non-selective growth, resulting in a degradation of the electrical performance. Ti/Ge:Ga(:B) contacts are finally evaluated, with the aim of providing new solutions for advanced Ge-based devices.