BIORESOURCE TECHNOLOGY
·
2019
·
IF 6.669
Xin Zhang,Ziguo Yuan,Qian Yao,Ying Zhang,Yao Fu
In this work, corn cob was used as raw material to selectively produce acetonitrile via catalytic fast pyrolysis (CFP) in ammonia over Ga/HZSM-5 catalyst. A series of catalysts with different catalyst carriers (including HZSM-5, USY, MCM-41, HY, and γ-Al 2 O 3 ) and active metals (including Fe, Co, Ni, Cu, Zn, Cr, Ca, Mg and Ga) were prepared and screened. The reaction conditions, such as temperature, ammonia flow rate and residence time were changed to investigate the effect on the product distribution and acetonitrile production. The results indicated that with the desired catalyst (2% Ga/HZSM-5) and optimal reaction conditions (Temperature 700 °C; ammonia flow rate 80 ml/min; residence time 2.4 s), the highest carbon yield of acetonitrile from corn cob with a value of 18.4% could be obtained, and the carbon selectivity in bio-oil was 83.5%. This study provides an economical and environmental-friendly method for the direct production of acetonitrile from abundant biomass.
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APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Xinxin Ren,Qingbo Yu,Jia Pan,Qingping Wang,Yuqi Li,Naishen Shi,Shuli Deng
It is well known that the design of precursor structure is an effective method to optimize the photocatalytic activity of g-C 3 N 4 , and it will be interesting to investigate the relationship between the precursor structure and the structure of the target catalyst. In this paper, by adjusting the addition amount of glutaraldehyde (GA), three kinds of glutaraldehyde/dicyandiamide (GA/DCDA) precursors with equilibrium/imbalance hydrogen bond interaction can be obtained, and the carbonized glutaraldehyde (C-GA)/g-C 3 N 4 composite catalysts with different carbon content can be obtained after calcination. The obtained C-GA/g-C 3 N 4 composite catalysts have different photocatalytic activity for methylene blue degradation. Compared with the original g-C 3 N 4 , the photocatalytic activity of C-GA/g-C 3 N 4 -2 composite is increased by 2.69 times. Through the analysis of thermal decomposition kinetics and structural characterization, we can see that the equilibrium interaction in the structure of GA/DCDA-2 precursor can promote the conversion of dicyandiamide to melamine, and glutaraldehyde carbonization will form more C-GA, and form a composite catalyst with closer interaction with g-C 3 N 4 . C-GA with close interaction and higher content can effectively promote the separation of photogenerated carriers and visible light absorption, thus improving its photocatalytic activity.
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2022
·Vol. 106
·期 1
·513-526
·
IF 4.186
Bingheng Sun,Benxue Jiang,Jintai Fan,Le Zhang,Long Zhang
Red-emitting color-convertors have attracted considerable attention for promising applications in solid-state lighting (SSL) to improve color rendition. However, the current nitride and fluoride phosphor powders have encountered several challenges, such as high cost, narrow emission bands, and insufficient stability during operation, which limit the development of high-power full-spectrum SSL. In this study, thermally robust Gd 3 (Al,Ga) 5 O 12 :Mn (GAGG:Mn) solid-solution ceramics (SSCs) with dual wavelength red-emission bands were prepared via an oxygen solid-state sintering reaction. The doped Mn ions occupied octahedral Al 3+ and Ga 3+ sites to generate Mn 4+ luminescent centers with pronounced deep-red emissions peaking at 698 nm ( 2 E → 4 A 2 ), and Mn 2+ luminescent centers with broad red emissions at 628 nm ( 4 T 1 → 6 A 1 ). Because the cationic radius matching effect induced the regulation of valence state of Mn, the photoluminescence of the GAGG:Mn SSCs can be tailored by the substitution of Al 3+ with Ga 3+ . Moreover, the Mn 3+ also existed in the GAGG lattice host, and their concentration decreased with increasing Ga 3+ contents owing to the mismatch of ionic radius between Mn 3+ and Ga 3+ ions. With the optimization of Al/Ga ratio and concentration of Mn ions, a broad emission band ranging from 550 to 800 nm (bandwidth = 250 nm) was achieved from Gd 3 Al 3 Ga 2 O 12 :0.3%Mn SSCs upon 465-nm excitation. Moreover, the GAGG:Mn SSC has over 17-fold enhanced thermal conductivity compared with the corresponding phosphor powder. This paper opens a door of regulating the valence state of luminescence centers with cation substitution and the application of oxide red-emitting color-convertors.
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APPLIED CATALYSIS A-GENERAL
·
2022
·
IF 5.723
Ge Yang,Xi Yan,Yan Chen,Xiao-Jing Guo,Wan-Zhong Lang,Ya-Jun Guo
In recent years, Ga-based catalysts attract much attention in propane dehydrogenation (PDH) reaction due to environmental friendliness and low cost. Nevertheless, it is still challenging to obtain high selectivity of propylene under harsh reaction conditions. In this work, the supported catalysts (Ga- x Mg/ZSM-5) were prepared with the sequential impregnation method and applied in the PDH reaction. The results show that MgO as an additive reduces the acidity of the catalysts, promotes the dispersion of Ga 2 O 3 and improves the selectivity of propylene. As a result, the average particle size of the Ga/ZSM-5 catalyst is larger (4.5 nm), and the initial propylene selectivity is only 71.0 %. In contrast, the optimal Ga-0.7Mg/ZSM-5 catalyst shows the smallest particle size (2.4 nm) and the highest propylene selectivity of 90.8 %. In comparison with the previous GaO x catalysts in literatures, the Ga-0.7Mg/ZSM-5 catalyst exhibits a superior production rate of propylene ( r C 3 H 6 ) based on either catalyst weight or Ga 2 O 3 weight.
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Molecular Catalysis
·
2021
·
IF 5.062
Huayan Zheng,Nilesh Narkhede,Guoqiang Zhang,Huacheng Zhang,Lina Ma,Shirui Yu
The small amount of promoter has shown increase in the methanol formation rate by several folds. Hence, hydrotalcite having sufficient trivalent cations are preferred; however, traditional coprecipitation route often leads to poor Cu dispersion owing to higher cationic charge in the layered structure that result in aggregation of the sheets. The present paper reports synthesis of porous, nanostructured Cu/ZnO/Ga 2 O 3 catalysts from pure phase hydrotalcite precursors by using aqueous miscible organic solvent treatment method. The 20% Ga containing catalyst showed ca. 2.5-fold increase in both surface area and % dispersion of the exposed Cu as compared to that prepared from standard coprecipitation method with similar composition. The stabilization induced by mutual dispersion of Cu, Zn and Ga components in the exfoliated sheets resulted in confinement of the Cu particle size up to 5 nm in the spent catalyst. The best performing catalyst of the series, Cu 0.4 Zn 0.4 Ga 0.2 -LDO exhibited STY of 762 mg•g Cat −1 •h −1 for methanol formation from syngas which was decreased by only 8.6% during 50 h of the reaction on stream. Further, it was revealed that, Ga is more conductive to stabilization of Cu as compared to Al, resulting in 23% higher methanol formation rate as compared to the Al containing catalyst.
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JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A
·
2021
·Vol. 110
·期 2
·273-286
·
IF 4.396
Kai Li,Hongchuan Tian,Ai Guo,Liguo Jin,Weizhen Chen,Bailong Tao
Bacterial infection and poor osteogenic capacity can result in the loosing or failure of titanium (Ti)-based implants in the clinic. Therefore, it is urgent to design an effective approach to enhance the osteogenic property and restrict bacterial activity. In this study, a layered double hydroxide (LDH) composed of Ga and Sr ions on Ti substrates by a hydrothermal method, then calcined in 250°C and denoted as LDH250. The scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were confirmed that the LDH films were successfully formed on the Ti substrates. Importantly, the obtained LDH films can induce an alkaline microenvironment around the Ti surface and regulate the behaviors of osteogenic cells and bacteria. In vitro cellular experiments, the LDH250 can enhance the differentiation of both MC3T3-E1 cells and osteoblasts, stimulate alkaline phosphatase activity (ALP), collagen secretion, and mineralization levels. Meanwhile, antimicrobial assay against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) demonstrated that the LDH250 samples had strong antibacterial abilities, which attributed to the release profile of Ga 3+ could act as a “Trojan horse” to destroy the bacterial iron metabolism, inducing of local alkaline environment, and producing reactive oxygen species. Hence, this study provides an effective method for reducing antibacterial infection and enhancing the bone integrative capacity of Ti-based implants for orthopedic applications.
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CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Guanliang Yu,Weirong Wang,Chun Jiang
Adjusted crystal fields can lead to new hybrid materials with promising optical performance. Transition metal ions (TMIs) with d-d electron transitions are sensitive to their surroundings and can be ideal candidates for crystal field research. Herein, we have selected single Ni 2+ -doped spinel oxide nanocrystals as a model system to systematically explore luminescence mechanisms in different crystal fields. Ni 2+ -doped ZnAl 2 O 4 , ZnGa 2 O 4 , and ZnCr 2 O 4 nanospinels with broad near-infrared (NIR) emission bands fully cover the second biological window (1100–1400 nm). We have developed a ZnX 2 O 4 (X = Al, Ga or Cr) (ZXO) spinel framework system using a melting-evaporation procedure, and the whole fabrication period only required 20 min. By changing X ions in the ZXO matrix framework, linear tunable photoluminescence was successfully realized. A sample with a mixed phase of ZnAl 2 O 4 and ZnCr 2 O 4 (ZACO) was also prepared using the same method, and ultrabroadband emissions ranging from 1050-1550 nm were detected. It is valuable to further explore the combinations based on these frameworks to realize tunable emission spectra. Fundamental research on the physical processes will open a new gateway for further research of TMI-doped nanocrystals with promising luminescence properties and broaden the applications to a variety of areas, especially in the biomedical field.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Jinxin Wei,Zhe Hu,Wenjie Zhou,Yi Qiu,Hanqing Dai,Yuanyuan Chen,Zhongjie Cui,Siyu Liu,Haiyang He,Wanlu Zhang,Fengxian Xie,Ruiqian Guo
With the blooming development of zero-dimensional nanomaterials , I-III-VI alloying quantum dots (QDs) with outstanding photoelectrical properties have emerged to attract much attention as promising environmentally-friendly substitutions for conventional binary Cd-based QDs. In this work, a facile one-pot method was introduced to synthesize unreported quaternary Ag-Cu-Ga-Se/ZnSe (ACGSe/ZnSe) QDs. A relatively high photoluminescence quantum yield (PL QY) of 71.9% and a tunable emission from 510 to 620 nm were successfully achieved. We explored the roles of alloying compositions in ACGSe/ZnSe QDs, inferring that increased Ag proportion would not only lower the V defect level which leads to the blue shift of emission, but also slow the ZnSe shelling process owing to the larger lattice distortion. At last, the white light-emitting diodes (WLEDs) were fabricated with ACGSe/ZnSe QDs as the conversion layer, indicating that the as-prepared QDs are a promising candidate for further applications.
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INORGANIC CHEMISTRY
·
2012
·
IF 4.601
Wenlong Yin,Kai Feng,Wendong Wang,Youguo Shi,Wenyu Hao,Jiyong Yao,Yicheng Wu
The twelve quaternary rare-earth selenides Ba2MLnSe5 (M = Ga, In; Ln = Y, Nd, Sm, Gd, Dy, Er) have been synthesized for the first time. The compounds Ba2GaLnSe5 (Ln = Y, Nd, Sm, Gd, Dy, Er) are isostructural and crystallize in a new structure type in the centrosymmetric space group P1̅ of the triclinic system while the isostructural compounds Ba2InLnSe5 (Ln = Y, Nd, Sm, Gd, Dy, Er) belong to the Ba2BiInS5 structure type and crystallize in the noncentrosymmetric space group Cmc21 of the orthorhombic system. The structures contain infinite one-dimensional anionic chains 1∞[GaLnSe5]4– and 1∞[InLnSe5]4–, and both chains are built from LnSe6 octahedra and MSe4 (M = Ga, In) tetrahedra in the corresponding selenides. As deduced from the diffuse reflectance spectra, the band gaps of most Ba2MLnSe5 (M = Ga, In; Ln = Y, Nd, Sm, Gd, Dy, Er) compounds are around 2.2 eV. The magnetic susceptibility measurements on Ba2GaGdSe5 and Ba2InLnSe5 (Ln = Nd, Gd, Dy, Er) indicate that they are paramagnetic and obey the Curie–Weiss law, while the magnetic susceptibility of Ba2InSmSe5 deviates from the Curie–Weiss law as a result of the crystal field splitting. Furthermore, Ba2InYSe5 exhibits a strong second harmonic generation response close to that of AgGaSe2, when probed with the 2090 nm laser as fundamental wavelength.
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CATALYSIS LETTERS
·
2025
·Vol. 155
·期 2
·1-15
·
IF 2.4
Li Ziyuan,Luo Mingsheng,Yang Zhi,Cui Xiaoteng,Yang Wenshuai,Xia Lingman,Shao Changke,Rahman Roshni
To effectively mitigate the global warming issue, it is crucial to develop advanced technologies that can significantly reduce carbon dioxide emissions. CO 2 hydrogenation for methanol synthesis is increasingly recognized as a promising chemical approach for the green-house gas utilization. In this study, we present a highly active, selective and stable Mo modified ZnCu-MOF and ZnCuAl-LDH composite catalysts, which achieves 18% CO 2 conversion and 70% methanol selectivity at 230 °C, 3.0 MPa at a space velocity of 3600 mL·g cat −1 ·h −1 . Furthermore, after 140 h of operation, the catalyst demonstrates superior durability. In-situ DRIFT results reveal that this CO 2 hydrogenation reaction over the ZnCu-MOF and ZnCuAl-LDH composite catalysts proceeds through key intermediate formate species, ultimately leading to the methanol formation. In contrast, the Mo-modified catalysts facilitate the CO insertion reaction (CO 2 → CO*, CO* + *CH x → CH 3 OH), thereby enhancing the methanol yield. Graphical
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CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Qin Zhang,Jiaqi Yang,Bo An,Ke Wang,Dongxing Song,Huijuan Su
Gd 0.1 Ce 0.9-x Ga x O 2-δ (x = 0, 0.04,0.07, 0.12) are synthesized via the citric acid-EDTA combustion method as an electrolyte material for intermediate-temperature solid oxide fuel cells. XRD and Rietveld refinement revealed that the material exhibits a single-phase cubic fluorite structure. SEM and EDS analyses demonstrated that the incorporation of Ga ions improved the sample's density, increased the grain size, and provided better element dispersion. XPS analysis confirms that Ga-Gd co-doping leads to increased oxygen vacancy concentration and modifies the oxidation states of Ce. Impedance spectroscopy results indicated that Ga-Gd co-doped ceria has higher ionic conductivity and lower activation energy compared to Gd single-doped ceria. In comparison to Gd 0.1 Ce 0.9 O 1.95 , the best-performing Gd 0.1 Ce 0.83 Ga 0.07 O 2-δ achieved nearly a 26-fold increase in ionic conductivity and a 66 % reduction in activation energy. The clearance coefficient of Gd 0.1 Ce 0.83 Ga 0.07 O 2-δ reached 100.95, while the blocking factor decreased by nearly 73 % compared to Gd 0.1 Ce 0.9 O 1.95 . The incorporation of Ga ions led to a nearly one order of magnitude reduction in the dissipation of oxygen vacancy concentration in the space charge layer, with the potential decreasing from 0.3971V (Gd 0.1 Ce 0.9 O 1.95 ) to 0.3117V (Gd 0.1 Ce 0.83 Ga 0.07 O 2-δ ). Dielectric studies clarified the contribution of the Gd-Ga synergistic effect on interfacial polarization. In terms of single-cell performance, the NiO-GDC| Gd 0.1 Ce 0.83 Ga 0.07 O 2-δ |LSCF cell exhibited higher power density and current density, particularly showing a 42.9 % performance improvement at 650 °C compared to NiO-GDC|Gd 0.1 Ce 0.9 O 1.95 |LSCF. Density functional theory calculations indicated that the incorporation of Ga ions effectively suppresses the electronic conductivity of CeO 2 and significantly reduces the formation energy, binding energy, and migration barrier of oxygen vacancies. Therefore, Ga-Gd co-doping can be regarded as an effective strategy for enhancing the performance of ceria-based electrolytes in IT-SOFCs.
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Materials
·
2024
·Vol. 17
·期 6
·1258
·
IF 3.1
Min Liu,Yansen Zhang,Song Hu,Guohong Zhou,Xianpeng Qin,Shiwei Wang
Ce-doped gadolinium gallium aluminum oxide (Ce: GGAG) precursors were first prepared by the microwave-assisted homogeneous precipitation method (MAHP). Thermal gravity-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), specific surface area analysis (BET) and field emission scanning electron microscopy (FE-SEM) were employed to investigate the crystal structure, phase evolution and morphologies of the Ce: GGAG precursors and powders. The influence of Ga ion concentration in the salt solution on the properties of Ce: GGAG powders was investigated. All the precursors were transformed into single-phase GGAG after being calcined at 950 °C in a furnace for 3 h. Monodispersed Ce: GGAG powders were obtained as the Ga ion concentration was lower than 0.06 mol/L. Single-phase and dense Ce: GGAG ceramics were obtained after sintering at 1600 °C in a flowing oxygen atmosphere for 10 h. Specifically, the Ce: GGAG ceramic reached its maximum density of ~6.68 g/cm3, which was close to its theoretical density of 6.70 g/cm3, and exhibited the highest optical transmittance of 65.2% at 800 nm after hot isostatic pressing sintering (HIP) as the Ga ion concentration was 0.02 mol/L. The decay time and light yield of the GGAG ceramic were 35 ns and 35,000 ± 1250 ph/MeV, respectively, suggesting that Ce: GGAG ceramics prepared using MAHP-synthesized nanopowders are promising for scintillation applications.
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