CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Hang Liu,Shengqiang Song,Andrie M. Garbers-Craig,Zhengliang Xue
Cr 2 O 3 is a well-known corrosion resistant oxide used in refractory applications. However, it can oxidize into toxic and water-soluble Cr(VI) compounds upon reaction with calcium aluminate cement phases in the presence of oxygen, which subsequently causes disposal problems after use. This study describes the extent to which chromium in the spinel Mg(Al,Cr) 2 O 4 phase can be oxidized to Cr(VI) when it reacts with the calcium aluminate cement phases C 12 A 7 , CA, CA 2 and free CaO at 1300 °C in air, using XRD, XPS and leaching tests (TRGS 613 standard) as analytical tools. On reaction with CaO, the Mg(Al,Cr III ) 2 O 4 spinel mainly transformed into hauyne (Ca 4 Al 6 Cr VI O 16 ) and Ca 5 Cr 3 O 12 which contains both Cr(IV) and Cr(VI). The reaction of C 12 A 7 and CA with the spinel phase also resulted in the formation of Ca 4 Al 6 CrO 16 . Conversely, the reaction of Mg(Al,Cr III ) 2 O 4 spinel with CA 2 resulted in the formation of only a trace amount of Cr(VI). Water-soluble Cr(VI) leached in large quantities (>100 mg/L) from samples where the Mg(Al,Cr III ) 2 O 4 reacted with either C 12 A 7 or CA. Almost no Cr(VI) leached from the sample when Mg(Al,Cr III ) 2 O 4 reacted with CaO, using the standard TRGS 613 leach test, but a significant amount of Cr(VI) was released into solution when leached with a HCl solution for 12 h. Both Cr(IV) and Cr(VI) present in the Ca 5 Cr 3 O 12 dissolved into acidic solution. Only a small amount of Cr(VI) leached from the sample that resulted when spinel was reacted with CA 2 , even after a prolonged HCl leach. Cr(III) in spinel Mg(Al,Cr) 2 O 4 is very stable and does not leach in either distilled water or acidic solution.
研究领域:
材料科学
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环境科学
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DOI
高影响因子
International Journal of Electrochemical Science
·
2023
·
IF 1.5
Sen Tian,Xuemei Ye,Yaping Dong,Wu Li,Bo Zhang,Bo Li,Haitao Feng
To synthesize Cr 2 O 3 from ferrochromium, the electrolysis of ferrochromium in an electrolyzing cell and the properties of Cr 2 O 3 prepared by thermal decomposition of (NH4)2CrO 4 were studied. Experimental results showed that with a 1:5 molar ratio of NH 3 ∙H 2 O:2CrO 4 2- and current density of 140 A/m 2 at room temperature, Cr and Fe can be completely separated by solid-liquid separation, and (NH 4 )2CrO 4 can be obtained. The optimized current efficiency was 62%. The four-step thermal decomposition process of (NH 4 )2CrO 4 was analyzed by TG-DTA. The XRD and FTIR results proved that crystalline Cr 2 O 3 with a fine particle size was obtained. Spherical Cr2O3 with a particle size of 71~216 nm and a specific surface area of 4~38 m 2 /g was confirmed by SEM and BET. UV-Vis results proved that Cr2O3 presented bright green (L*=34.78~49.97, a*=0.91~-14.73, and b*=6.08~17.92), and the forbidden band width was 1.91~2.25 eV. The purity of Cr 2 O 3 was over 99%.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Hang Liu,Shengqiang Song,Pin-Wen Guan,Guixuan Wu,Mithun Nath
Despite great potential in several applications, the pseudo-ternary system Al 2 O 3 –CaO–Cr 2 O x is an overlooked phase diagram due to the formation of a few toxic, carcinogenic, and water-soluble Cr 6+ compounds. In the research paper, equilibrium experimentation of selected compositions was conducted at 1073, 1373, and 1673 K and investigated using XRD , SEM-EDS, and leaching tests. Further, thermodynamic modeling of limited databases of the pseudo-ternary system Al 2 O 3 –CaO–Cr 2 O x was validated using DFT calculations. Including the recently discovered novel phase CaAl 2 Cr 2 O 7 (wuboraite), the seven phases not available in the SGTE SUBstance (SSUB) database, along with the CaCrO 4 and CaCr 2 O 4 phases existing therein, were modeled using Density Functional Theory (DFT). Based on the above experiments and the present CALPHAD model, we have calculated the isothermal sections (1073, 1373, and 1673 K) of the Al 2 O 3 –CaO–Cr 2 O x system for different oxygen partial pressures ( P (O 2 )= 0.21 atm and P (O 2 )= 10 −8 atm).
研究领域:
材料科学
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化学工程
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DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
De-Rui Kong,Yu-Ying Xin,Xian-Fa Zhang,Zhao-Peng Deng,Li-Hua Huo,Shan Gao
The development of a non-enzymatic electrochemical sensor possessing well dual-sensing to H 2 O 2 and glucose remains challenging due to less report. Herein, spinel CoCr 2 O 4 nanoparticles with small size were synthesized by sol–gel reaction, which were then simply mixed with commercial graphene under ultrasonic to obtain uniformly dispersed CoCr 2 O 4 /Graphene composite. They were deposited onto the surface of bare glassy carbon electrode (GCE) through a common drop-coating method. The CoCr 2 O 4 /Graphene/GCE sensor firstly achieves highly dual-sensing to H 2 O 2 and glucose in 0.1 M NaOH solution. At 0.4 and 0.55 V, its sensitivities to H 2 O 2 and glucose can separately reach up to 1168.6 and 1722.5 μA mM −1 cm −2 , and the corresponding detection limits are as low as 18 nM and 12 nM. These key indexes are the best among reported dual-functional spinel oxide-based electrodes. This excellent electrochemical sensing ability stems from its large electrode active area, good conductivity, and the synergism between graphene and CoCr 2 O 4 nanoparticles with mixed redox couplings, which provides an efficient platform for dual-sensing detection. In addition, the modified electrode can accurately determine glucose in human tears, rat serum and orange juice, as well as H 2 O 2 in milk whey, mouthwash and disinfectant, thus predicting its good application prospects.
研究领域:
电化学传感器
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材料科学
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分析化学
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DOI
高影响因子
Nanoscale
·
2023
·Vol. 15
·期 41
·16741-16751
·
IF 6.7
Jin Song,Fenglong Wu
The hydrolysis of ammonia borane (NH3BH3) on metal-based heterogeneous catalysts under light irradiation has been considered as an efficient technique for hydrogen (H2) generation, in which the activity of the catalyst can be improved by increasing the electron density of the active metal. However, studies focused on reducing the electron density of the active metal are rare. Here, we report an electron density manipulation strategy to prepare highly electron-deficient ultrathin Co nanosheets via transferring nanosheets to support mesoporous Cr2O3 by simple one-step in situ reduction (denoted as Co/Cr2O3). X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) spectra confirm the formation of electron-deficient Co nanosheets and the Co–O–Cr bond due to electron transfer from the nanosheets to mesoporous Cr2O3. Importantly, the Co–O–Cr bond can work as a bridge to accelerate the electron transfer under light irradiation and then improve the electron-deficiency degree of Co nanosheets. As a result, the optimal Co/Cr2O3 exhibits a high intrinsic catalytic performance with the turnover frequency (TOF) value of 106.8 min−1 and significantly reduces the activation energy (Ea) to 16.8 kJ mol−1 under visible light irradiation, which make it among the best ever recorded monometallic Co-based catalyst with enriched electrons. The density functional theory (DFT) calculation results suggest that the electron-deficient Co nanosheets are responsible for the greatly decreased H2O activation and dissociation energy barriers and then the acceleration of the evolution of H2. The work provides a new perspective for designing high efficiency catalysts for H2 production, which is beneficial for relative energy conversion and storage catalysis.
研究领域:
材料科学
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催化化学
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能源转换与存储
✓ 已验证
DOI
PubMed
高影响因子
International Journal of Applied Ceramic Technology
·
2020
·Vol. 18
·期 3
·684-696
·
IF 1.762
Zhengkun Cai,Minjin Jiang,Qianqian Guo,Xiaosong Jiang,Song Chen,Hongliang Sun
High-density chromium deficient calcium-doped lanthanum chromite-based ceramics (La 0.8 Ca 0.2 Cr 0.98 O 3 ) were prepared by hot pressing (HP) at different sintering pressures, and the highest density can reach 98.8%. The effects of sintering pressure on the microstructure, mechanical properties, and electrical conductivity of La 0.8 Ca 0.2 Cr 0.98 O 3 materials were studied. The experimental results show that HP can increase the density of lanthanum chromite-based ceramic materials and significantly inhibit the growth of grain size. As the sintering pressure increases, the strength and hardness gradually increase, but the fracture toughness decreases. When the sintering pressure is greater than 58 MPa, the presence of the second phase CaCr 2 O 4 can be detected in the XRD results of the sintered ceramics. The SEM results showed that CaCr 2 O 4 had two completely different morphologies in the sintered ceramics, and it was initially speculated that the possible causes were due to two different generation pathways. The electrical conductivity decreases with increasing sintering pressure, whereas the maximum electrical conductivity obtained is 18.61 S/cm in vacuum at 800°C for pressureless sintering ceramic.
研究领域:
材料科学
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陶瓷工程
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DOI
高影响因子
Toxics
·
2025
·Vol. 13
·期 4
·262
·
IF 4.1
Wei Zhang,Huan Yang,Shaohong You,Xia Zhong,Pingping Jiang,Xudong Lan,Rui Ma
Current research focuses more on redox of toxic Cr(VI), with less attention to Cr(III) changes in flooded soil. First, the structure of acid birnessite and cryptomelane was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and other test methods. This study investigated farmland soil in Yuxi, Yunnan Province, under flooding stress induced by the addition of two distinct concentrations of manganese oxides. Throughout the experiment, key physicochemical properties of the soil—including pH, redox potential (Eh), Cr(VI) concentration, and chromium speciation—were systematically measured and analyzed. Structural characterization demonstrated distinct morphological and surface area properties. Specifically, acid birnessite, with petal-like stacked spheres, has a specific surface area of 103.76 m2/g, while cryptomelane, strip-shaped, has an area of 95.92 m2/g. The submergence experiment yielded the following phenomena: (1) During the 60-day flooding experiment, soil amended with 0.5% or 1% acid birnessite or cryptomelane exhibited an increase in Eh compared to the control group. (2) At the end of the 60-day submergence period, the Cr(VI) concentration in the soil treated with 1% acid birnessite increased by 2.4 times compared to the control group. In addition, after 60 days, Cr(VI) concentrations in the soil exceeded 5 mg/L in soils with manganese oxide added to them. This study evaluates how manganese oxides oxidize Cr(III), aiding in assessing their environmental risks and long-term impacts on metal transformation. The findings help predict chromium behavior in farm soils and guide remediation strategies.
研究领域:
环境科学
·
土壤学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2019
·
IF 3.218
Meng Zhang,Zhengwei Xiong,Jinzhi Jia,Zhangyang Zhou,Botao Wu,Yuanyuan Ni,Xiuwen Zhou,Linhong Cao
A hollow Cr 2 O 3 /CrN nanoshell was synthesized directly in the ammonia atmosphere. X-ray diffraction analysis indicated that the crystalline phase was gradually transformed from the hexagonal Cr 2 O 3 to cubic CrN, in company with the shrinking of the lattice cells with the increase of ammonification time. Based on its more stable crystalline structure and well conductivity of the CrN relative to the Cr 2 O 3 , the electrochemical performance of Cr 2 O 3 /CrN composites was modified, including increased specific capacitance, enhanced cycle stability and improved electrical conductivity. While the ratio of oxygen to nitrogen is 81.89%, the Cr 2 O 3 /CrN composites own the highest specific capacitance of 333.2 F/g at 10 mV/s and maintain an initial capacitance of 84.7% after 5000 charge-discharge cycles, attributing to the maximum specific surface area. The variation of electrochemical properties of Cr 2 O 3 /CrN composites was systematically studied. These results provided a new route for designing transition metal oxides/transition metal nitrides composites as electrode materials for supercapacitors .
研究领域:
材料科学
·
电化学
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Honghong Lei,Peng Jiang,Bin Li,Yuncheng Zhou,Rui Zhang,Jianlei Kuang,Wenbin Cao,Wei Wang
The (S, N) co-doped Ba 2 In 2- x Cr x O 5+ y (0 ≤ x ≤ 0.5) oxides are successfully obtained by mixing the Ba 2 In 2- x Cr x O 5+ y oxides and thiourea through a simple ball milling method followed by sintering at 400 °C for 3 h. The colors of the compounds change from orange-brown to yellow-green after reacting with thiourea. When Cr amount is small ( x = 0.1), the crystal structure of (S, N) co-doped Ba 2 In 2- x Cr x O 5+ y is orthorhombic Ba 2 In 2 O 5 phase. When x ≥ 0.3, the crystal structure of the sample is cubic BaInO 2.5 phase. And this phase transition is the same as Ba 2 In 2- x Cr x O 5+ y . XPS results reveal that Cr 6+ in Ba 2 In 2- x Cr x O 5+ y (0 ≤ x ≤ 0.5) oxides are reduced to Cr 3+ after sintering. S exists in both cation and anion forms, and N exists in substitutional forms. UV–Vis analysis indicates that the yellow-green hue comes from the d-d transition of Cr 3+ , and the doping of S, N ions leads to a red shift of the absorption edge of the samples.
研究领域:
材料科学
·
化学
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DOI
高影响因子
Solar RRL
·
2021
·Vol. 5
·期 5
·2100064
·
IF 8.582
Zhiyuan Xu,Shanglong Peng,Hao Lin,Shuhao Tian,Zilei Wang,Jian He,Lun Cai,Juan Hou,Pingqi Gao
Compared with vacuum evaporation, metal oxides deposited by solution process exhibit advantages, for example, dopants can be easily incorporated in a wide range and the contents are easy to be regulated by changing the composition of precursors. Herein, solution-processed p-type copper-doped chromium oxide (Cu:CrO x ) films with tunable oxygen vacancy are demonstrated via a postannealing process. The synthetic and postannealing temperature have a significant impact on the chromium cation oxidation state in the Cu:CrO x films, leading to the variation of work function for the oxide films. By adjusting the work function of Cu:CrO x films, a low contact resistivity of 95 mΩ cm 2 can be realized for the Ag/Cu:CrO x /p-Si contact. Finally, the optimized Cu:CrO x films are used as the hole transporting layer in c-Si solar cells, showing an increased power conversion efficiency from 15.2% (without Cu:CrO x ) to 16.9% (with Cu:CrO x ). The results show an effective stage to use p-type metal oxides as a hole-selective layer in c-Si solar cells.
研究领域:
材料科学
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能源技术
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产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Fei Xue,Fengzhu Zhao,Jihui Wang,Wenbin Hu
Zn 1- x Cr x O resistive switching film with different Cr content was prepared on SS304 substrate by sol–gel method combined with spin plating and heat treatment. The surface morphology, composition, structure, semiconductor type and oxygen vacancy concentration of Zn 1- x Cr x O films were observed and analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Mott-Schottky curves, X-ray photoelectron spectroscopy (XPS) electron paramagnetic resonance spectroscopy (ESR) and density functional theory (DFT) calculation. And the corrosion resistance of Zn 1- x Cr x O film were investigated by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the prepared Zn 1- x Cr x O films have a uniform dense surface which belongs to n -type semiconductor type, and the oxygen vacancy concentration in the films increases with the increase of Cr content. With the increasing of Cr content, the corrosion resistance of films is decreased. During the immersion process, the corrosion resistance of Zn 1- x Cr x O film is firstly increased and then decreased with increasing immersion time. By applying immersion and polarization treatment the corrosion resistance of Zn 1- x Cr x O film could be regulated between the high and low resistance states (HRS and LRS) due to the creation and disappearance of oxygen vacancies in the film.
研究领域:
材料科学
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电化学
·
表面科学
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产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2025
·
IF 5.1
Wei Wu,Xiaohui Sun,Xueying Zhao,BAOLEI LIU,Guohua Wu,Xuyang Zhang,Bo Wang,Xiangwei Wang,Xianhui Rong,Nana LIU
Polymer dispersed liquid crystals (PDLC), as an electrochromic material, can rapidly undergo reversible switching between scattering and transparent states, demonstrating significant potential in electro-optic fields. However, traditional PDLC films are limited to simplicial transition between a scattering state and a transparent state without switchable colors, lacking the opportunity for adaptive camouflage especially in military related items. In this study, chromium trioxide (Cr2O3) and ionic liquid (IL) were incorporated into the PDLC, enabling color change through redox reactions between the IL and liquid crystal molecules with reversibly transition from green to yellow, possessing excellent electrochromic adaptive camouflage performance. By applying a 5 V electric field, the PDLC films can be successfully manipulated to simulate the colors of various terrestrial backgrounds, including the green forests, the yellow and green mountainous regions, the yellow wilderness areas, the white snow, and the yellow deserts. This research provides new insights into the application of PDLC films for switchable color adaptive camouflage, broadening the application range of PDLC.
研究领域:
材料科学
·
光学工程
·
军事应用
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）