JOURNAL OF THE AMERICAN CERAMIC SOCIETY
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2020
·Vol. 104
·期 6
·2860-2867
·
IF 3.502
Da-Wang Tan,Zhen-Yong Lao,Zhan Zhang,Wei-Ming Guo,Shi-Kuan Sun,Hua-Tay Lin
B 4 C-TiB 2 ceramics (TiB 2 ranging 5~70 vol%) with Mo-Co-WC as the sintering additive were prepared by spark plasma sintering. In comparison with B 4 C-TiB 2 without additive, the enhanced densification was evident in the sintered specimen with Mo-Co-WC additive. Core-rim structured grain was observed around TiB 2 grains. The interface of the rim between TiB 2 and B 4 C phases demonstrated different feature: the inner borderline of the rim exhibited a smooth feature, whereas a sharp curved grain boundary was observed between the rim and the B 4 C grain. The formation mechanism is discussed: the epitaxial growth of (Ti,Mo,W)B 2 rim around the TiB 2 core may occur as a result of the solid solution and dissolution-precipitation between TiB 2 phase and the sintering additive. It was revealed that the fracture toughness increased as the content of TiB 2 content increased, alongside the decreased hardness. B 4 C-30 vol% TiB 2 specimen demonstrated the optimal combination of mechanical properties, reaching Vickers hardness of 24.3 GPa and fracture toughness of 3.33 MPa·m 1/2 .
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高影响因子
CHEMOSPHERE
·
2020
·
IF 5.778
Jianjun Lian,Heli Wang,Hongping He,Weilin Huang,Mei Yang,Yin Zhong,Ping’an Peng
Iron sulfide (FeS) is an important scavenger for hexavalent molybdate (Mo(VI)) in an anoxic environment; it plays a crucial role in the mobilization and transformation of Mo(VI), although the underlying reaction mechanisms between Mo(VI) and FeS remain unclear. This study investigates the Mo(VI) reaction kinetics with the amorphous FeS over a pH range 5.0–9.0 and Mo’s chemical form on the FeS surface. It is found that the Mo(VI) reaction kinetics with FeS follow a pseudo first-order model, and the reaction rate constant ( k obs ) increases with a decrease in the pH value. The k obs at pH 5.0 is 0.027 min −1 , which is about 38 times higher than that at pH 9.0. The rapid Mo(VI) removal under acidic conditions is due to quick Mo(VI) transformation into stable MoS 2 and thiomolybdate (Mo V O x S y ). The amount of MoS 2 formed on the surface of FeS increases with a decrease in the pH value. Under neutral and alkaline conditions, Mo(VI) is not transformed into MoS 2 by FeS because the precipitation of iron oxy-hydroxide passivates the active sites of FeS. The study also investigates the effect of the initial dosage of FeS (20–200 mg L −1 ) and Mo(VI) (10–50 mg L −1 ) on the reaction kinetics of Mo(VI) with FeS. The results provides important information on the environmental fate of Mo(VI) in the anoxic environment containing amorphous FeS.
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Journal of Materials Chemistry C
·
2020
·Vol. 8
·期 27
·9337-9344
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IF 7.059
Aili Wang,Lili Zhao,Hui Liu,Ziqian Zhou,Chengbo Li,Yong Xiang,Weijia Zhou,Feng Hao
The development of low-dimensional non-precious metal catalysts for the hydrogen evolution reaction (HER) is highly desired for clean energy utilization. Herein, we have reported a facile synthesis protocol of Cu–Mo–O (CMO) nanowires and nanosheets on Cu foam (CMOW/CF and CMOS/CF) through a one-step reaction of Cu nanowires with (NH4)6Mo7O24 solution directly under mild conditions. The final product morphology has been tuned by mechanical stirring. The as-synthesized CMOS/CF exhibits a low operating overpotential of 112 mV at a current density of 10 mA cm−2 with a high electrochemical active area of 25.1 mF cm−2 and excellent long-term stability in the 1 M KOH electrolyte. Moreover, by using the CMOS/CF as cathodic and anodic electocatalysts, a two-electrode electrolyzer capable of driving 10 mA cm−2 at a cell voltage of 1.69 V was achieved, along with promising stability. The high performance of the CMOS/CF can be attributed to higher electrochemical area and more Mo catalytic sites induced by mechanical stirring. This work provides a facile method for the synthesis and catalytic site regulation through a simple method of low-dimensional nanomaterials for the HER with relatively high electrochemical active area and catalytic activity.
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MATERIALS RESEARCH BULLETIN
·
2016
·
IF 2.435
Honghong Liu,Hong Gong,Mingming Zou,Heng Jiang,Rasaki Sefiu Abolaji,Ayesha Khan Tareen,Branislav Viliam Hakala,Minghui Yang
Mo-N-co-doped mesoporous TiO 2 microspheres were synthesized via a solvothermal method, followed by nitriding treatment under ammonia gas flow. The efficiency of the samples was investigated by monitoring the degradation of Rhodamine-B under visible light irradiation. The experimental results revealed that Mo-N-co-doped mesoporous TiO 2 microspheres showed better performances than Mo-TiO 2 microspheres. It was observed that; 0.1% molar quantity of Mo doped on TiO 2 at 500 °C for 2 h under nitriding conditions gave highest photocatalytic activities. The nitridation under ammonia gas of Mo-TiO 2 samples created oxygen vacant sites and led to incorporation of substitutional and interstitial Nitrogen. The enhanced visible light photocatalytic activities of Mo-N-co-doped TiO 2 photocatalyst was attributed to the large surface areas, narrow band gap and intense light absorbance in visible region. This study may create a promising and eco-friendly method towards synthesis of metal and non-metals co-doped on semiconductor materials to improve their photocatalytic activities and applications.
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高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2024
·
IF 8
Jiacheng Xi,Kai Liang,Niu Yao,Huiyu Yuan,Junyan Cui,Xinghui Hou
Hydrogen sulfide (H 2 S) is a toxic and flammable substance that its effective real-time detection has great significance for ensuring safety. Currently, the detection of low concentration H 2 S remains a challenge. In this paper, the 3D monoclinic-tetragonal mixed phase Mo/Bi- x with hierarchical structure has been successfully prepared by a simple one-step solid-phase method for low concentration H 2 S detection. The effect of Mo doping on its morphology, structure, composition and gas sensitivity of BiVO 4 has been investigated. XRD, SEM, TEM, Raman, UV–vis and XPS techniques are employed to explore the potential sensing mechanism. The results show that the addition of Mo leads to a gradual transformation of BiVO 4 from a class cube structure to a strip structure, accompanied by partial conversion of the monoclinic phase to the tetragonal phase. For the typical sample (Mo/Bi-0.1), it exhibits extremely high response ( R g / R a ) of 43.5–10 ppm H 2 S at 200 °C, high selectivity ( Q H 2 S / methanol = 7.15 ), rapid response and recovery time of 11/15 s and relatively low theoretical detection limit (20.5 ppb). This can be attributed to the presence of unique long plate structures, abundant oxygen vacancies, chemisorbed oxygen and a monoclinic-tetragonal phase heterojunction. This research provides a potential strategy for the design of other H 2 S sensitive materials.
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ACS Catalysis
·
2024
·
IF 11.3
Miao Liu,Ying He,Ying-Ying Jiao,Ling Ding,Di An,Yang Yang,Qing-Qing Hao,Hui-Yong Chen,Qun-Xing Luo
The nature of Mo-catalyzed glucose epimerization in the aqueous phase was elaborately studied. We herein formulate the thermodynamic properties (e.g., ΔrHT, ΔrGT, and Keq.T) of the reversible epimerization by collecting the equilibrium composition. The isotopic tracing and NMR spectra show that the overall tautomerization network encompasses the reversible epimerization and isomerization and the irreversible degradation of all hexoses. The leaching tests and kinetic and spectroscopic studies reveal that glucose epimerization catalyzed by Mo-containing solid catalysts in the aqueous phase resembles homogeneous catalysis. All catalysts enable a near-equilibrium yield of mannose (28%) at 373 K except MoP but undergo a different kinetic course of which MoN is the best catalyst according to the apparent kinetic parameters. The molybdenum species dissolved in an aqueous solution evolves into the truly active centers of the MoVI–O–MoVI bridged polymolybdates. Moreover, we propose that a single Mo center as Lewis acidic site coordinates with the aldoses to form a bidentate complex, which thereby contributes two different mechanisms to generate the epimers, viz., the intramolecular 1, 2-carbon exchange and two-step isomerization. The former proceeds through a three-membered cyclic transition state (TSC) that mediates the simultaneous cleavage of the bond between C-2 and C-3 and formation of the bond between C-1 and C-3, whereas the latter undergoes two hydride transition states (TSH-1 and TSH-2) via the hydride transfer twice, leading to the chiral inversion of the configuration at C-2. Last but not least, the presence of phosphates in an aqueous solution leads to the deactivation of Mo-based catalysts because of the interplay between glucose and phosphates.
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Molecular Catalysis
·
2024
·
IF 3.9
Xiaoyu Yan,Xiaoqing Xu,Yuhan Sun,Xiuyi Li,Jiale Xu,Renjie Ji,Rui Huang,Chunyi Li
Compared with propane dehydrogenation (PDH) technology, oxidative dehydrogenation (ODH) of propane is an effective way to break through the thermodynamic constraints, which has changed the endothermic reaction into exothermic. Meanwhile, coking in PDH was significantly reduced by the presence of an oxidant in ODH of propane. Therefore, ODH of propane has attracted wide interest and has been studied in recent years. However, the contradiction between the conversion of propane and the selectivity of propene was the intrinsic problem of ODH of propane that required further study. In this work, a novel aluminum/potassium-doped mixed metal oxide catalyst Mo 1 V 0.5 Al 0.02 K 0.03 O x was synthesized using a simple co-impregnation method, whose selectivity for propene (83.2 %) and conversion of propane (12.7 %) at 300 °C were the best among all other alkali metal/alkaline-earth metal-doped catalysts. The further discussion illustrated that doping potassium and alumina could synergistically adjust the density of acid sites on the catalyst, establishing an equilibrium between high propane conversion and the ideal propene selectivity. After modification, the density of Brønsted acid decreased, leading to an enhancement in the selectivity of propene. Simultaneously, the addition of steam in the feed gas promotes propene to oxygenates and improves the conversion of propane under the condition of constant contact time.
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MOLECULES
·
2024
·Vol. 29
·期 15
·3633
·
IF 4.2
Shihao You,Jing Di,Tao Zhang,Yufeng Chen,Ruiqin Yang,Yesong Gao,Yin Li,Xikun Gai
To explore advanced oxidation catalysts, peroxymonosulfate (PMS) activation by Co-Ni-Mo/carbon nanotube (CNT) composite catalysts was investigated. A compound of NiCo2S4, MoS2, and CNTs was successfully prepared using a simple one-pot hydrothermal method. The results revealed that the activation of PMS by Co-Ni-Mo/CNT yielded an exceptional Rhodamine B decolorization efficiency of 99% within 20 min for the Rhodamine B solution. The degradation rate of Co-Ni-Mo/CNT was 4.5 times higher than that of Ni-Mo/CNT or Co-Mo/CNT, and 1.9 times as much than that of Co-Ni/CNT. Additionally, radical quenching experiments revealed that the principal active groups were1O2, surface-bound SO4•−, and •OH radicals. Furthermore, the catalyst exhibited low metal ion leaching and favorable stability. Mechanism studies revealed that Mo4+on the surface of MoS2participated in the oxidation of PMS and the transformation of Co3+/Co2+and Ni3+/Ni2+. The synergism between MoS2and NiCo2S4reduces the charge transfer resistance between the catalyst and solution interface, thus accelerating the reaction rate. Interconnected structures composed of metal sulfides and CNTs can also enhance the electron transfer process and afford sufficient active reaction sites. Our work provides a further understanding of the design of multi-metal sulfides for wastewater treatment.
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iScience
·
2024
·
IF 4.6
Jinhu Wang,Junyu Gao,Yingxuan Miao,Dong Li,Yunxuan Zhao,Tierui Zhang
While photocatalytic technology has brought additional opportunities and possibilities for the green conversion and sustainable development of ammonium-based nitrogen fertilizers, the low activation efficiency of the molecular N 2 has impeded its further application feasibility. Here to address the concern, we designed an amorphous molybdenum hydroxide anchored on the ultrathin magnesium-aluminum layered double hydroxide (Mo@MgAl-LDH) nanosheets for benefiting the N 2 photofixation to NH 3 . With the aid of the designed amorphous Mo(V) species, the pristine MgAl-LDH exhibited a considerable performance of nitrogen photofixation under visible light irradiation (NH 3 production rate of 114.4 μmol g −1 h −1 ) due to the improved N 2 activation efficiency. The work demonstrated a feasible strategy for nitrogen photofixation using amorphous Mo(V) species, which may also deliver a novel inspiration for the development of amorphous photocatalysts toward the photoactivation of molecular N 2 .
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JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
·
2025
·
IF 3
Qi Li,Zhangqiao Zhou,Yan Nie,Lu Yang,Yu Wang,Jinsong Chen,Xian Wang
The preparation of soft magnetic composites requires effective surface modification of alloy powder to enhance insulating properties and achieve dense, uniform coating layers. Firstly, the gas-atomized Fe-Ni-Mo powder was surface modified using the atomic layer deposition method, forming a uniform and dense Al 2 O 3 insulating layer. The secondary surface modification of organic polymers further improves the properties of soft magnetic composites. This study systematically evaluates the effects of the primary and secondary surface modification on the properties of powder particles and soft magnetic composites. The primary modification generates an extremely thin insulating layer of approximately 2.5 nm, which increases the particle resistivity by 9 orders of magnitude. The permeability frequency stability of the soft magnetic composites increased from 11.3 % to 96.5 %, resulting in significant core loss reduction. The secondary modification effectively enhances the formability of soft magnetic composites. Optimal permeability of 242.7 at 1 kHz is achieved, maintaining 95.2 % frequency stability up to 1 MHz, while core loss remains below 570 mW cm −3 under 100 kHz/100 mT conditions. The surface treatment method in this work can provide a reference for the surface insulation modification of soft magnetic composites.
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Nanoscale
·
2025
·Vol. 17
·期 27
·16515-16522
·
IF 5.1
Zhengwei Li,Zixuan Fang,Jiajun Zhu,Wenxi Yang,Yubing Guo,Fan Wang,Jiyang Li,Mengqiang Wu
NCA (LiNixCoyAl1−x−yO2, x ≥ 0.8) cathode materials have become some of the leading candidates for lithium-ion batteries due to their superior specific discharge capacity and more cost-effective production. Yet, NCA materials are facing significant challenges such as surface reconstruction and micro-cracks, which adversely impact their electrochemical performance and practical application. Herein, a simple doping modification strategy using high-valence Mo6+ cations is proposed to address these issues. The experimental analysis results demonstrate the following: (1) the high-valence Mo6+ cations provide additional positive charge and reduce the migration barrier for Li+, thereby improving the Li+ transport kinetics of NCA; (2) Mo6+ doping not only refines the primary particle size, which compacts the stacking of particles, but also optimizes the microstructure of NCA, which prevents the development of micro-cracks and thus enhances the interfacial and bulk-phase stability of NCA; (3) acting as lattice pillars in the TM layers, the high-valence Mo6+ cations increase the thermodynamic barrier for Ni2+ migration from TM sites to lithium sites as well as strengthen the binding with oxygen atoms, thereby suppressing surface reconstruction and oxygen release. Based on the results of electrochemical testing, the prepared Li(Ni0.80Co0.15Al0.05)0.995Mo0.005O2 (NCAM-1) demonstrates a remarkable capacity retention rate of 89.3% after 100 cycles within the voltage range of 3.0–4.3 V and at a rate of 1C, which is significantly higher than the 79.1% retention observed for Li(Ni0.80Co0.15Al0.05)O2 (NCA). Additionally, NCAM-1 delivers a specific discharge capacity of 153.5 mA h g−1 at a high rate of 10C, which is substantially elevated compared to that of NCA (113.5 mA h g−1).
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MINERALS ENGINEERING
·
2020
·
IF 3.795
Hai Yan,Bingqiao Yang,Mengyuan Zeng,Pengliang Huang,Aiping Teng
Molybdenite and chalcopyrite is generally separated through the selective depression of chalcopyrite using potentially toxic depressants such as sodium sulfide and cyanides. In this work, xanthan gum (XG), a polymer polysaccharide, was investigated as a potential molybdenite depressant in copper-molybdenum sulfides separation. Single mineral flotation tests indicated that molybdenite could be effectively depressed by XG, while chalcopyrite was slightly affected. The artificial mixed minerals flotation tests proved that molybdenite and chalcopyrite could be selectively separated with the addition of XG. The adsorption mechanism was studied through zeta potential and infrared spectroscopy measurements. The results revealed that XG mainly adsorbed on molybdenite surfaces other than chalcopyrite. In a word, the experiments results illustrated that XG could be applied as a promising depressant in the selective flotation separation of molybdenite and chalcopyrite, which has the advantage of environment compatibility over conventional copper depressants.
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