JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Changsheng Wu,Zhiyong Wang,Xianbo Jin
Niobium (Nb) is primarily used as the active material in Nb electrolytic capacitors in the form of metallic fine powder. Unlike traditional methods of preparing niobium powder through chemical or electrochemical reduction of metal compounds in molten salts, we report here the efficient preparation of Nb nanopowder via electrolysis of NbS 2 in the NaCl-KCl melt at 973 K. The NbS 2 is simply synthesized by carbo-sulfidation of Nb 2 O 5 . The following electro-desulfidation in the molten electrolyte converts solid NbS 2 into Nb nanopowder at the cathode, with S 2- ions moving to the anode and being oxidized to gaseous sulfur. The reduction path was verified to be NbS 2 → L x NbS 2 → NbS 2-w → Nb. Through constant cell electrolysis at 2.9 V, NbS 2 is rapidly reduced to nodular Nb nanopowder (50-100 nm), with a Current efficiency and energy consumption of approximately 94% and 3.58 kW·h kg⁻¹ Nb, respectively.
研究领域:
材料科学
·
电化学
·
纳米技术
·
冶金学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Fei Yan,Xiaotong Ding,Yanxin Quan,Xiaolong Yang,Haoyu Sun,Juanjuan Qi,Ping Li,Lidong Wang
Dimethyl sulfoxide (DMSO) is an important solvent in numerous industries. The biodegrading process of DMSO is slow and produces toxic volatile compounds including CH 3 SCH 3 , CH 3 SH, and H 2 S. Hence, it is important to develop chemical methods for treating DMSO-containing wastewater. In the present work, niobium oxyhydroxide and niobium oxide were synthesized and used to activate hydrogen peroxide for the degradation of DMSO to DMSO 2 . The niobium oxyhydroxide catalyst exhibited much better catalytic activity for DMSO oxidation than niobium oxide. EPR spectra and radical scavenging experiments confirmed that O 2 •− and 1 O 2 are the main active species for the oxidation of DMSO. FTIR analysis and DFT calculation confirmed that the surface hydroxyl of niobium oxyhydroxide can be substituted by hydroperoxo group of H 2 O 2 to form Nb−OOH group, which can directly oxidize DMSO or indirectly oxidize DMSO via O 2 •− and 1 O 2 . However, H 2 O 2 cannot form hydroperoxo group on the surface of niobium oxide, which might trigger the lower activity of niobium oxide catalysts than the niobium oxyhydroxide catalyst. The niobium oxyhydroxide catalyst exhibited good reusability and was promising for the treatment of DMSO-containing wastewater.
研究领域:
环境化学
·
催化
·
废水处理
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2022
·Vol. 105
·期 12
·7455-7466
·
IF 4.186
Fangyi Huang,Hua Su,Qin Zhang,Xiaohui Wu,Yulan Jing,Yuanxun Li,Xiaoli Tang
The BaZnP 2− x Nb x O 7 microwave dielectric ceramics were prepared by solid-state reaction method to investigate the impact of Nb 5+ on the composition, microstructure, and vibrational properties, as well as sintering characteristics and microwave dielectric properties. The solubility of Nb 5+ in the BaZnP 2− x Nb x O 7 lattice was limited. A moderate amount of Nb 5+ substitution could promote the densification process. The vibrational characteristics of the BaZnP 2 O 7 ceramics were first studied by performing experimental and theoretical Raman and infrared spectroscopy measurements in this work, and their relationship with the microwave dielectric properties was studied. The acquired results showed that (Ⅰ) ε r was influenced by both the density and the second phase; (Ⅱ) the density and full width at half maximum of the Raman vibrational peak played a critical role in affecting the Q × f values. The BaZnP 2− x Nb x O 7 samples sintered at 925°C exhibited the outstanding microwave dielectric properties with x = 0.02: ε r = 7.98, Q × f = 60 615 GHz (tan δ = 2.18 × 10 −4 ; f = 13.21 GHz) and τ f = −52.93 ppm/°C ( ρ bulk = 4.03 g/cm 3 ; ρ r = 92.69%). The proposed ceramic is expected to be used in microwave substrates.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2025
·
IF 2.5
Si Guo,Chao Deng,Gang Shi,Dawei Wang,Likui Wang
MXenes are emerging as highly promising materials for pseudocapacitive applications, offering exceptionally high specific capacitance. To date, over 30 distinct MXene compositions and nearly 20 solid solutions have been synthesized in the lab. However, research predominantly centers on Ti3C2Tx and a handful of other single-metal MXenes, with scant attention paid to solid-solution MXenes. Herein, a series of solid solution MAX phases (Nb1−yTiy)4AlC3 and corresponding (Nb1−yTiy)4C3Tx MXenes have been synthesized. The maximum proportion of Ti that can be incorporated into the M site has been examined. We found that the rate performance of MXenes improves with increasing Ti content. Especially, (Nb0.7Ti0.3)4C3Tx and (Nb0.6Ti0.4)4C3Tx retain 62.92% and 68.38% of their capacitances, when the scan rate is increased from 5 mV s−1 to 1000 mV s−1, respectively, compared to Nb4C3Tx's 13.88% retention. (Nb0.7Ti0.3)4C3Tx shows a specific capacitance of 311.06 F g−1 under a current density of 1 A g−1 and good cycling stability. This research demonstrates that the electrochemical characteristics of (Nb1−yTiy)4C3Tx solid solution MXenes can be manipulated by adjusting the ratio of transition metals.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
RARE METALS
·
2021
·Vol. 41
·期 1
·166-178
·
IF 4.003
Zhang Bo-Lin,Deng Li-Feng,Liu Bo,Luo Chun-Yun,Liebau Michael,Zhang Shen-Gen,Gläser Roger
Abstract Combining the redox properties of Co and the acid properties of Nb in a Co 3 -Nb-O x catalyst is shown to provide superior performance in the selective catalytic reduction of NO with NH 3 (NH 3 -SCR). Co 3 O 4 shows average activity, however, it exhibits a poor N 2 selectivity. Nb 2 O 5 is not active for NH 3 -SCR. However, the mixed Co 3 -Nb-O x catalyst shows higher NO conversion and N 2 selectivity than the single Co 3 O 4 and Nb 2 O 5 catalysts at 100–300 °C. The results of temperature programmed reduction by H 2 and X-ray photoelectron (XP) spectra indicate that the addition of Nb changes the chemical states of Co and decreases the concentration of Co 3+ and O α , adjusting the activity for catalytic oxidation to a moderate level. This suppresses the formation of undesired N 2 O from the over-oxidation of NH 3 . Incorporation of Co and Nb into one solid synergistically couples their redox behavior and surface acidity, ensuring the high catalytic activity and N 2 selectivity in NH 3 -SCR. Graphical Abstract
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2024
·Vol. 171
·期 12
·122505
·
IF 3.1
Dongsheng Jiang,Zhuan Zhao,Huan Zhang,Ruifang Wang,Jianxun Song,Yusi Che,Jilin He
In this study, metallic niobium was produced by electrolysis in a NaCl-KCl melt using NbCxOy as a soluble anode. The anodic dissolution behavior of NbCxOy in the NaCl-KCl melt and the reduction mechanism of niobium ions were examined using cyclic voltammetry, linear sweep voltammetry, square wave voltammetry, electrochemical impedance spectroscopy, and chronopotentiometry. The results revealed that the electrode reduction process of niobium ion was Nb(Ⅴ) → Nb(Ⅲ) → Nb(Ⅰ) → Nb, with these reactions being diffusion-controlled. During successive multiturn scans, the reduction process of niobium ions favored the pathway of Nb(V) → Nb(III) → Nb. As the electrolytic voltage increased, the dissolution of niobium ions in NbCxOy also increased, with a tendency to oxidize into high-valence niobium ions. Constant-current electrolysis in a NaCl-KCl melt, using NbCxOy as the anode and Mo rods as the cathode resulted in the deposition of mainly metallic niobium on the Mo cathode, manifesting that NbCxOy can be used to extract metallic niobium. This study provides a theoretical foundation for the realization of a green and efficient extraction process for metallic niobium.
研究领域:
冶金学
·
电化学工程
✓ 已验证
产品关联
DOI
高影响因子
HYDROMETALLURGY
·
2021
·
IF 4.156
Linquan Sun,Hongdong Yu,Fancheng Meng,Tao Qi,Shili Zheng,Yihe Peng,Lina Wang
Niobium consumption has burgeoned owing to the increasing application of niobium in critical industries, including the aerospace and oil and gas industries. Conventional metallurgical technologies and separation methods for niobium extraction use highly concentrated HF, which is hazardous to both humans and the environment. A solvent extraction system comprising trioctyl tertiary amine (N235) and 4-methyl-2-pentanone (MIBK) that can extract and separate niobium from an oxalate-containing H 2 SO 4 solution is proposed in this paper. Niobium solutions tend to contain titanium and iron impurities; therefore, the effects of various conditions on the separation of the three elements were investigated. The extraction mechanism and thermodynamics of the process were also examined. Over 82% niobium was extracted at an organic-to-aqueous phase ratio of 1:1 and the H + concentration of 8.29 mol/L using an organic phase with 50 vol% N235 and 50 vol% MIBK as the extractants at 20 °C. Only 18.4% titanium and 3.35% iron were co-extracted. Two stripping processes, both of which further separated niobium and titanium, are also proposed herein. The possible composition of the niobium-containing extraction complex was [(R 3 NH)·NbO(C 2 O 4 ) 2 (H 2 O) 2 ], as supported by a Fourier transform infrared spectroscopy (FT-IR) analysis and ultraviolet–visible (UV–vis) spectrophotometry . The extraction mechanism was inferred to be the association of R 3 NH + in N235 with the [NbO(C 2 O 4 ) 2 (H 2 O) 2 ] − from the acidic niobium-containing solution, and the stripping mechanism was concluded to be anion exchange. The enthalpy change (∆H o ) of the extraction system was −11.0 kJ/mol at 288.15–313.15 K, which indicated that niobium extraction from the H 2 SO 4 solution with oxalate using N235 and MIBK was an irreversible exothermic process.
研究领域:
冶金学
·
化学工程
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2024
·
IF 20.2
Shiyong Mou,Siyuan Liu,Weidong Dai,Yanjuan Sun,Fan Dong
Electrochemical oxidative amidation (EOA) strategies offer a sustainable and potentially promising route for amide synthesis. However, the efficiency and activity of catalysts under oxidative conditions are highly dependent on noble metals. Herein, we present our experimental findings and fundamental understanding that fluorine-doped Nb 2 O 5 nanosheet arrays on carbon paper (F-Nb 2 O 5 /CP) serve as an efficient and robust non-noble catalyst for the electrochemical synthesis of formamide from ammonia and methanol under ambient conditions. In 0.5 M KHCO 3 solution, this catalyst achieved a high Faradaic efficiency of 52.0 %, with an N selectivity of 79.1 % at 1.5 V versus Hg/HgO electrode. The catalyst exhibited remarkable stability, maintaining its performance over 120 h. By integrating in-situ spectroscopy studies with density functional theory calculations, we revealed that fluorine doping induces a shift in the d-band center of the Nb site. This shift alters the adsorption behavior of OH - and *NH 2 intermediate on the F-Nb 2 O 5 (100) surface, thereby effectively lowering the C-N coupling energy barrier, and boosting the production of formamide.
研究领域:
材料科学
·
电化学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
He Sun,Jiaming Chen,Yusheng Yang,Min Qiu,Milin Zhang
A low-grade ore containing 4 % niobium and 7 % titanium has been extracted from Bayan Obo tailing, but its potential has not been fully utilized. This study aims to recover the niobium and titanium elements from this low-grade ores in the form of their carbides. The process involves reducing niobium and titanium to (Nb,Ti)C through a carbothermal process. During this process, iron and silicon are also reduced to Fe-Si intermetallic compounds, allowing (Nb,Ti)C to diffuse into them. Subsequently, selective electrochemical oxidation is used to separate (Nb,Ti)C from the Fe-Si intermetallic compounds in an aqueous ferrous sulfate solution. The Fe-Si intermetallic compounds are first oxidized to the Fe 3 Si phase, and then to the Fe 5 Si 3 phase in the solution with pH 0.35. The (Nb,Ti)C/matrix interfaces are identified as the preferred site of electrochemical pitting corrosion. By exploiting the electrochemical oxidation reaction of iron in the matrix, (Nb,Ti)C powders are separated along these interfaces. The by-products of this process are FeSi alloys, which are evaluated for their electrocatalytic properties in oxygen evolution reactions. It is found that the Fe 5 Si 3 alloy by-product exhibits good electrocatalytic activity and kinetics in the oxygen evolution reaction, demonstrating its potential for practical applications.
研究领域:
冶金学
·
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
·
2025
·
IF 4.6
Qinglin Zeng,Bochao Xu,Zepeng Lv,Shaolong Li,Jilin He,Jianxun Song
This study demonstrates the synthesis of a NbC x O y solid solution through carbothermic reduction and the subsequent extraction of metallic niobium through molten salt electrolysis. Thermodynamic analysis and carbothermic reduction were conducted to determine the optimal conditions for synthesizing the NbC x O y solid solution at different compositions, enabling precise control over their composition. Furthermore, metallic niobium was produced via the molten salt electrolysis of the selected NbC x O y solid solution for 16 h at 2.9 V in the NaCl–KCl eutectic molten salt at 750 °C.
研究领域:
材料科学
·
冶金工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
·
2020
·
IF 2.463
Xingbang Dong,Huanjun Zhang,Yang Yang,Shiquan Feng,Zheng Wang,Chaosheng Yuan,Kun Yang,Xuerui Cheng
InNbO 4 and InNbO 4 :Eu 3+ phosphors were synthesized by solid-state reaction method. The structural stability and crystal field under high pressure are investigated up to 34.5 GPa using in-situ Raman and luminescence spectra . The evolution of Raman and luminescence spectra with pressure of InNbO 4 revealed one reversible phase transition at around 12 GPa. A progressive red shift and luminescence quenching were observed for InNbO 4 :Eu 3+ phosphors during compression. The pressure-induced variation of local environment and crystal field around Eu 3+ ions was analyzed using Judd–Ofelt (J-O) intensity parameter Ω 2. Both the parameter Ω 2 and luminescence property were indicative of a pressure-induced lower asymmetry around Eu 3+ sites in InNbO 4 . These results suggest that the pressure has a great influence on fluorescence intensity and energy levels of Eu 3+ ions.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Le Fu,Fuqing Jiang,Bo Li,Yongxin Cheng,Guofu Xu,Jiwu Huang,Håkan Engqvist,Wei Xia
The addition of dopant(s) is an effective strategy to regulate the microstructure and properties of ZrO 2 -based ceramics. In this study, we investigated the effects of ternary element alloying, namely tantalum (Ta), niobium (Nb), and hafnium (Hf) elements, on the microstructure and transformability of ZrO 2 nanocrystallites in a ZrO 2 -SiO 2 nanocrystalline glass-ceramic (NCGC) during sintering and thermal treatments. The ternary dopants enhanced the transformability of tetragonal ZrO 2 (t-ZrO 2 ) nanocrystallites during sintering, i.e., the dopants acted as t-ZrO 2 destabilizer. The Ta, Nb and Hf elements dissolved in ZrO 2 nanocrystallites, forming ZrO 2 solid solution. Meanwhile, lamella nanotwins were formed within many ZrO 2 nanocrystallites. No obvious segregation of dopants was detected at ZrO 2 grain boundaries. t-ZrO 2 and monoclinic (m) ZrO 2 nanocrystallites were metastable in thermal treatments process, with “t” to “m” and the reverse “m” to “t” polymorphic transformation occurred simultaneously. Meanwhile, t-ZrO 2 and m-ZrO 2 nanocrystallites had a great tendency to grow larger during thermal treatments.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）