Energies
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2021
·Vol. 15
·期 1
·53
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IF 3.004
Kai Miao,Tan Li,Jing Su,Cong Wang,Kaige Wang
Catalytic hydropyrolysis via the introduction of external hydrogen into catalytic pyrolysis process using hydrodeoxygenation catalysts is one of the major approaches of bio-oil upgrading. In this study, hydrodeoxygenation of acetone over Mo/HZSM-5 and HZSM-5 were investigated with focus on the influence of hydrogen pressure and catalyst deactivation. It is found that doped MoO3could prolong the catalyst activity due to the suppression of coke formation. The influence of hydrogen pressure on catalytic HDO of acetone was further studied. Hydrogen pressure of 30 bar effectively prolonged catalyst activity while decreased the coke deposition over catalyst. The coke formation over the HZSM-5 and Mo/HZSM-5 under 30 bar hydrogen pressure decreased 66% and 83%, respectively, compared to that under atmospheric hydrogen pressure. Compared to the test with the HZSM-5, 35% higher yield of aliphatics and 60% lower coke were obtained from the Mo/HZSM-5 under 30 bar hydrogen pressure. Characterization of the spent Mo/HZSM-5 catalyst revealed the deactivation was mainly due to the carbon deposition blocking the micropores and Bronsted acid sites. Mo/HZSM-5 was proved to be potentially enhanced production of hydrocarbons.Keywords:hydrodeoxygenation;biomass;hydropyrolysis;MoO3;bifunctional catalysts
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HYDROMETALLURGY
·
2021
·
IF 4.156
Yubiao Li,Qihang Xiao,Zhiming Li,Andrea R. Gerson
The slow leaching rate of molybdenite (MoS 2 ), due to its inert nature, and low recovery hinders the application of traditional hydrometallurgical processing. This study investigated the effects of grinding speed and time, molar ratio of sodium chlorate (NaClO 3 , oxidant) to MoS 2 , leaching time and temperature on the leaching efficiency of molybdenum (Mo). Grinding at low speeds via mechanical activation decreased particle size. However, at speeds over 450 rpm for 1.0 h, or at lower speeds but with longer time, it triggers a solid-state reaction (mechanochemistry) producing soluble Na 2 Mo 2 O 7 . This may be due to the existence of an energy threshold for the solid-state reaction. The most suitable activating conditions were 600 rpm for 0.5 h, with a molar ratio of NaClO 3 : MoS 2 = 5, leached in 0.1 M NaOH solution for 2.0 h at 348 K, giving rise to a Mo recovery of 74.8%. The initial acid leaching stage of the ground mixture is dominated by the dissolution of Na 2 Mo 2 O 7 , giving rise to elevated Mo recovery. The later stage is controlled by the dissolution of MoS 2 , slowing down the increase in Mo extraction. As compared to alkaline conditions, acidic leaching of MoS 2 ground at low speeds (non solid-state reaction) gives greater Mo recovery, due to the greater activity of NaClO 3 to MoS 2 under acidic conditions. However, the greatest Mo recovery is achieved in alkaline solution for MoS 2 ground at high speed (solid-state reaction) due to the occurrence of mechanochemical reaction.
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JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Xin Zhou,Haopeng Luo,Bo Sheng,Xingyu Chen,Yihao Wang,Quanyuan Chen,Juan Zhou
The limited production of Cu + in the Cu 2+ /PMS processes constrained its large-scan application for the elimination of organic pollutants . In this study, molybdenum powder (Mo) was applied as the co-catalyst to improve the degradation of 2,4-dichlorophenol (2,4-DCP) in Cu 2+ /PMS system at pH 5.6. By the assistance of Mo, Cu 2+ was rapidly reduced to Cu + which exhibited super activity for the peroxymonosulfate (PMS) activation. Compared with Cu 2+ /PMS processes, the PMS decomposition rate and 2,4-DCP degradation efficiency respectively increased by 62.1% and 83.6% in the Mo co-catalytic Cu 2+ /PMS system after reaction for 20 min. The degradation of 2,4-DCP was completed via both the free radical and non-radical pathways and the free radicals rather than Cu 3+ contributed most to the reaction. In contrast to fresh Mo, the ratio of Mo 4+ increased and Mo 6+ decreased in the used Mo powder, due to the oxidation of Mo 0 by Cu 2+ and/or ∙OH and the reduction of Mo 6+ by O 2 ∙ − . Additionally, the coexistence of Cl - and humic acid with low concentrations showed little effects on the Mo/Cu 2+ /PMS system while HCO 3 − presented an obvious depression for 2,4-DCP degradation. During five cycling runs, all the degradation rates were higher than 92.8%, indicating the good stability of Mo/Cu 2+ /PMS system.
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ACS Nano
·
2020
·
IF 14.588
Feng Ma,Yangyang Wan,Xiaoming Wang,Xinchao Wang,Jiashun Liang,Zhengpei Miao,Tanyuan Wang,Cheng Ma,Gang Lu,Jiantao Han,Yunhui Huang,Qing Li
The sluggish kinetics of lithium polysulfides (LiPS) transformation is recognized as the main obstacle against the practical applications of the lithium–sulfur (Li–S) battery. Inspired by molybdoenzymes in biological catalysis with stable Mo–S bonds, porous Mo–N–C nanosheets with atomically dispersed Mo–N2/C sites are developed as a S cathode to boost the LiPS adsorption and conversion for Li–S batteries. Thanks to its high intrinsic activity and the Mo–N2/C coordination structure, the rate capability and cycling stability of S/Mo–N–C are greatly improved compared with S/N–C due to the accelerated kinetics and suppressed shuttle effect. The S/Mo–N–C delivers a high reversible capacity of 743.9 mAh g–1 at 5 C rate and an extremely low capacity decay rate of 0.018% per cycle after 550 cycles at 2 C rate, outperforming most of the reported cathode materials. Density functional theory calculations suggest that the Mo–N2/C sites can bifunctionally lower the activation energy for Li2S4 to Li2S conversion and the decomposition barrier of Li2S, accounting for its inherently high activity toward LiPS transformation.
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JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
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2020
·
IF 3.442
Yuting Song,Wencheng Fang,Caixia Liu,Zhixia Sun,Fengyan Li,Lin Xu
Modification of semiconductor materials by polyoxometalates (POMs) is a promising strategy for increasing their photoelectrocatalytic (PEC) activity. In this work, we synthesized POM-modified CdS composite nanocrystals based on three kinds of Keggin-type mixed-addendum Mo/W POMs (Ag 3 PMo 3 W 9 O 40 , Ag 3 PMo 6 W 6 O 40 , and Ag 3 PMo 9 W 3 O 40 ). This is the first report on the semiconductor properties of the three Keggin-type mixed-addendum Mo/W POMs. Their PEC performances were studied by transient photocurrent responses, electrochemical impedance spectroscopy , and PEC oxidation of As(III) to As(V). The PEC performances of POM-modified CdS composite nanocrystals (CdS/Ag 3 PMo 3 W 9 O 40 , CdS/Ag 3 PMo 6 W 6 O 40 , and CdS/Ag 3 PMo 9 W 3 O 40 ) were superior to the performance of pure CdS nanocrystals. CdS/Ag 3 PMo 3 W 9 O 40 composite nanocrystals exhibited the highest efficiency for the PEC oxidation of As(III) to As(V), which was about 85% higher than that of the pure CdS nanocrystals. The present study provides insight into developing novel composite nanocrystals with Keggin-type mixed Mo/W POMs for efficient PEC oxidation.
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JOM
·
2021
·Vol. 73
·期 11
·3451-3459
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IF 2.474
Chen Ben,Li Zhi-Bo,Zhang Guo-Hua,Chou Kuo-Chih
To improve the performance of Mo-based cermets, Mo-(Ni)-Al 2 O 3 cermets were prepared with raw materials of nano-sized Al 2 O 3 powder. The effects of Al 2 O 3 and Ni additions on the densification behavior, microstructure, bending strength, and hardness of the Mo-(Ni)-Al 2 O 3 cermets were experimentally analyzed. The results showed the content of Al 2 O 3 had a great influence on the degree of densification of Mo-Al 2 O 3 cermets at the sintering temperature of 1600°C. In addition, the Al 2 O 3 particles were distributed evenly in the matrix of Mo-based cermets, which refined the grains of Mo and increased the hardness of cermets. Because of the weak interfacial bonding strength between Al 2 O 3 ceramic phase and Mo metal phase, the bending strength decreased continuously with increasing Al 2 O 3 content. However, Ni addition improved the wetting and adhesion of Al 2 O 3 and Mo. With the addition of Ni, the relative density increased, and thus hardness and bending strength were improved.
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Catalysis Science & Technology
·
2021
·Vol. 11
·期 22
·7445-7453
·
IF 6.119
Yijuan Wang,Ziyi Guo,Jianzhi Wang,Ningbo Yu,Yanan Xue,Faquan Yu
Crystal structure and morphology can be regulated by inducing the positioning growth of metal sulfide, which is an efficient strategy to improve the oxygen evolution activity of the anode. Herein, solid NiMoO4 nanoplate arrays were used as cages to immobilize the metal source, and Mo doped NiSx is obtained by in situ solvothermal sulfuration reaction with polysulfide as the sulfur source. The electronic structure, conductivity, crystallographic phase and microscopic morphology of oxygen evolution catalysts could be controlled simultaneously by polysulfide induced solid metal oxide sulfidation, thereby greatly improving their electrocatalytic oxygen evolution activity. Benefiting from these, the prepared Mo doped nickel-sulfur electrodes show great performance toward the oxygen evolution reaction with overpotentials of 184 mV and 240 mV at current densities of 50 and 100 mA cm−2 in alkaline electrolyte. This study provides a new pathway by polysulfide induced sulfidation based on solid metal oxide for developing metal sulfide electrode materials with high oxygen evolution reaction performance for overall water splitting.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
·
IF 4.939
Ying Gao,Hanwei He,Wenyu Tan,Yizhi Peng,Xiaomei Dai,Yihui Wu
Exploring efficient, abundant, low-cost and stable materials for hydrogen evolution reaction (HER) is highly desired but still a challenging task. Herein, Ni–Se–Mo electrocatalysts supported on nickel foam (NF) substrate were synthesized by a facile one-step electrodeposition method. The Ni–Se–Mo film presents high electrocatalytic activity and stability toward HER, with a low overpotential of 101 mV to afford a current density of 10 mA cm −2 in 1.0 M KOH medium. Such excellent HER performance of Ni–Se–Mo film induced by the synergistic effects from Mo-doped Ni–Se film leads to the fast electron transfer . This work provides the validity of interface engineering strategy in preparing highly efficient transition metal chalcogenides based HER electrocatalysts.
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Catalysis Science & Technology
·
2020
·Vol. 10
·期 5
·1368-1375
·
IF 5.721
Cankun Jiang,Lulu Zhang,Fan Gao,Xueyan Huang,Rui Lei,Yun Ye,Jie Yuan,Ping Liu
A CdS@MoOx core–shell nanorod photocatalyst has been constructed by a one-step in situ photodeposition method, which effectively utilizes the photoproduced-hole-induced dehydration and condensation of Mo–O–H derived from the hydrolyzed product of MoCl5, to successfully deposit a layer of MoOx on the surface of CdS NRs. X-ray photoelectron spectroscopy further confirmed that S–Mo bonds serve as bridges for carrier transport between the core and the shell, significantly reducing the interface impedance and improving the carrier transmission efficiency. Due to the superior interfacial carrier separation as well as the enhanced light absorption, the optimal CdS@MoOx-0.9 nanocomposite exhibits a high hydrogen production performance (5.42 mmol g−1 h−1) under visible light irradiation (λ > 400 nm). We have experimentally shed light on the mechanism of this excellent enhancement performance in detail. Moreover, our work can broaden the range of construction and application of developing other photocatalytic materials containing transition metal oxides.
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ACS Applied Energy Materials
·
2020
·
IF 4.473
Yin’an Zhu,Ye Pan,Weiji Dai,Tao Lu
Electrochemical splitting of water to hydrogen is widely considered as an efficient and sustainable solution to relieve the energy crisis. In this work, we report a facile dealloying method based on metallic glass (Ni61Zr36Mo3) to introduce abundant oxygen vacancies (Ov) for the electrocatalytic hydrogen evolution reaction (HER). The corroded ribbons are composed of a sandwich-like structure with Ni–Mo–O nanoporous layer outside and raw metallic glass inside. This complex structure delivers a low overpotential of 71 ± 2.6 mV at −20 mA cm–2geo in 1.0 M KOH solution, a Tafel slope of 57 ± 3 mV dec–1, and 100 h long-term stability for HER, which is much better than those of the crystallized counterpart, nanoporous Ni, and the commercial benchmark 20% Pt/C electrocatalyst. The high concentration of oxygen vacancies (71.5%), the alloying effect of Mo, and amorphous composition synergistically contribute to the superior electrocatalytic ability and enhanced reaction kinetic of nanoporous Ni–Mo–O, indicating it an excellent low-cost alternative for platinum in hydrogen production.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2018
·
IF 4.229
Cong Wang,Hongli Wang,Zhili Wang,Xiaoju Li,Yue Chi,Minggang Wang,Dawei Gao,Zhankui Zhao
Ammonia borane (AB) has been identified as one of the most promising candidates for chemical hydrogen storage . However, the practical application of AB for hydrogen production is hindered by the need of efficient and inexpensive catalysts. For the first time, we report that the incorporation of Mo into Cu@Co core-shell structure can significantly improve the catalytic efficiency of hydrogen generation from the hydrolysis of AB. The Cu 0.81 @Mo 0.09 Co 0.10 core-shell catalyst displays high catalytic activity towards the hydrolysis dehydrogenation of AB with a turnover frequency (TOF) value of 49.6 molH 2 mol cat −1 min −1 , which is higher than most of Cu-based catalysts ever reported, and even comparable to those of noble-metal based catalysts. The excellent catalytic performance is attributed to the multi-elements co-deposition effect and electrons transfer effect of Cu, Mo and Co in the tri-metallic core-shell NPs.
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INORGANIC CHEMISTRY
·
2024
·
IF 4.3
Jianmin Li,Changyan Guo,Yanan Niu,Xianglei Cao,Jiang Li,Jide Wang
The photocatalytic oxidation of benzyl alcohol and the simultaneous evolution of hydrogen from water are efficient dual-optimal routes. It is important to develop composite catalysts that combine redox properties and facilitate electron–hole separation and transport. Herein, the bimetallic-doped Mo-ZIS@Ti photocatalyst was designed and synthesized, and the selective oxidation of benzyl alcohol and hydrogen evolution by water splitting was realized at the same time. Under visible light irradiation, benzyl alcohol was completely converted with more than 99% selectivity for benzaldehyde, and the H2 production rate was 5.6 times higher than the initial ZIS. The exceptional catalytic performance was ascribed to utilizing Ti-MIL-125 as a precursor, wherein slowly releasing-doped Ti formed robust Ti–S bonds that quickly transfer electrons and reduce sites. Meanwhile, doping Mo effectively captures photogenerated holes and acts as active sites for oxidation reactions. Both experimental characterization and work function calculations demonstrate that the bimetallic synergism effectively modulates the electronic structure of ZIS, promotes the directional separation of electrons and holes, and significantly improves the photoactivity and stability of ZIS. This work contributes a route to obtain benzaldehyde and green hydrogen at the same time and also gives new insights for the construction and mechanism study of bimetallic-doping catalysts.
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