JOURNAL OF PHYSICS D-APPLIED PHYSICS
·
2022
·Vol. 55
·期 45
·454001
·
IF 3.409
Ru-Yi Liu,Lei Ding,Guo-Duo Yang,Jia-Yu Zhang,Rui Jiao,Hai-Zhu Sun
Although graphitic carbon nitride (g-C3N4) is one of the most promising metal-free semiconductors in the field of photocatalytic hydrogen production, the preparation of efficient g-C3N4-based photocatalysts is still a challenge. Herein, the strategy of element doping and co-catalyst loading are employed to make an effective modification on g-C3N4. The Mo2C hollow nanospheres supported by porous B-C3N4 (B-doped g-C3N4) flakes, namely, B-C3N4/Mo2C photocatalysts are successfully constructed by the ultrasonic self-assembly-calcination approach. The unique Mo2C hollow nanospheres structures increases internal multiple visible light scattering, which facilitates light-harvesting, shortens the transport distance of carriers, and hence reduces the carriers recombination. Impressively, B-C3N4/Mo2C-35 exhibits excellent activity in photocatalytic hydrogen production, affording an H2 production rate up to 1696.4 µmol g−1 h−1, which is higher than B-C3N4/3 wt% Pt photocatalyst. Moreover, the apparent quantum efficiency of B-C3N4/Mo2C-35 at 420 nm is 2.12%. Mechanism studies suggest that this desired photocatalytic performance is attributed to a broader light absorption range, more reactive sites and faster carrier transfer rate than that of pure g-C3N4. This work develops a noble metal-free hollow nanosphere co-catalyst system and proposes new insight into the design of g-C3N4-based composite photocatalysts.
研究领域:
材料科学
·
化学工程
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环境科学
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能源科学
✓ 已验证
DOI
高影响因子
Nano Energy
·
2023
·
IF 17.6
Wei Zhong,Siwu Li,Mengchuang Liu,Qiang Wu,Ziqi Zeng,Shijie Cheng,Jia Xie
The self-sacrificing Li 2 C 2 O 4 is a promising lithium replenisher benefiting from its high specific capacity, residue-free and low-cost properties. However, the intrinsic low electrochemical activity leads to a decomposition potential up to 4.7 V, posing a challenge for the compatibility of electrolyte and cathode materials . Herein, a three-dimensional (3D) hierarchical spherical Mo 2 C/N-doped graphene co-catalysts is synthesized by self-polymerization and high-temperature annealing. It is shown that the synergistic catalytic effect of Mo 2 C and N-doped activated graphene enhances the reactivity of Li 2 C 2 O 4 and the hierarchical three-dimensional conducting network accelerates the electron-ion transport. When the nano-Li 2 C 2 O 4 is homogeneously encapsulated in the spherical catalytic center using a freeze-drying technique, the electrochemical reaction of Li 2 C 2 O 4 is greatly promoted, resulting a significant drop of decomposition potential from 4.7 V to 4.16 V. As a result, the specific capacity of Gr||LFP and SiC||LFP full cells with composite lithium replenisher can be increased by 15% and 22%, respectively. Moreover, the solid electrolyte interface (SEI) is appropriately strengthened with pre-lithiation and thus guarantees superior cycling performance.
研究领域:
材料科学
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电化学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
Science China-Materials
·
2022
·Vol. 66
·期 3
·903-912
·
IF 8.64
Zhong Wei,Zhang Ce,Li Siwu,Zhang Wei,Zeng Ziqi,Cheng Shijie,Xie Jia
Irreversible lithium loss in the initial cycles appreciably reduces the energy density of lithium-ion batteries. Prelithiation is an effective way to compensate for such lithium loss, but current methods suffer from either the instability or low capacity of prelithiation reagents. Lithium oxalate (Li 2 C 2 O 4 ) has shown great potential as a lithium-compensation material because of its high theoretical capacity (equivalent to lithium metal), low cost, and air stability. However, the practical applications of Li 2 C 2 O 4 are limited by its low electrochemical activity and high critical decomposition voltage. In this study, we performed the prelithiation of a low-voltage cathode by using Mo 2 C catalysis and nano-Li 2 C 2 O 4 . Results show that the Mo 2 C catalyst changes the electron cloud distribution around Li 2 C 2 O 4 and greatly reduces the activation energy, thereby significantly accelerating the lithium release from Li 2 C 2 O 4 . The nano-Li 2 C 2 O 4 prepared by freeze-drying shows accelerated ionic and electronic conduction as well as close contact with Mo 2 C. Benefiting from the synergistic effect, the decomposition potential of Li 2 C 2 O 4 is decreased by 0.5 V with an efficiency close to 100%. The LiCoO 2 ∥SiO full cell empowered with the nano-Li 2 C 2 O 4 /Mo 2 C prelithiation composite demonstrates 46.9% higher capacity than the control and thus has great potential for practical applications.
研究领域:
储能
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材料科学
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电化学
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纳米技术
✓ 已验证
DOI
高影响因子
Materials Today Sustainability
·
2022
·
IF 7.244
Y. Liu,H. Liu,L. Tian,L. Pang,X. Liu,J. Li
As a most promising potential next-generation energy storage system , lithium-sulfur batteries (Li–S batteries) received great attention in recent years. However, how to effectively prevent the shuttling effect and accelerate the redox reaction kinetics of polysulfides are still a challenge. Herein, a strategy of using the soft template as a pore-forming agent was proposed to prepare Mo 2 C/nitrogen-doped carbon hollow microflowers (marked as H–Mo 2 C/NC MFs), which was used as an efficient absorbent and electrocatalyst of polysulfides for Li–S batteries. Due to the physical limitations of assembling the special nanosheet into a hollow carbon matrix in the shape of a microflower, the H–Mo 2 C/NC MFs can be used as an appropriate S loading substrate. With the synergistic chemisorption from pyridine N sites and high content polar Mo 2 C nanoparticles , the as-prepared H–Mo 2 C/NC MFs can provide enhancing adsorption and catalytic conversion for polysulfides. As a result, the H–Mo 2 C/NC/S MFs-based cathode provides a high initial discharge capacity of 1104.8mAh/g at 0.2C. Even at the high rate of 1.0C, the initial capacity of 705.2mAh/g still shows good electrochemical performance, and in 1000 cycles, the average capacity decay rate is only 0.016%, with supercycle stability. This article provided a new strategy for a novel viewpoint for the reasonable design of conductive and polar materials for efficient and durable Li–S batteries.
研究领域:
能源材料科学
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电化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Chemistry
·
2020
·
IF 7.216
Nan Jiang,Guangyu Jiang,Dechao Niu,Jiayi Mao,Meiwan Chen,Kaiyuan Li,Yongsheng Li
The low sulfur utilization and fast capacity fading resulting from the sluggish redox reaction and abominable polysulfides shuttle greatly hinder the practical applications of lithium-sulfur (Li-S) batteries. Herein, we develop a facile “ in-situ growth” method to decorate ultra-small Mo 2 C nanoparticles (US-Mo 2 C) on the surface of Ketjen Black (KB) to functionalize the commercial polypropylene (PP) separators, which can accelerate the redox kinetics of lithium polysulfides conversion and effectively increase the utilization of sulfur for Li-S batteries. Importantly, the US-Mo 2 C nanoparticles have abundant sites for chemical adsorption towards polysulfides and the conductive carbon networks of KB have cross-linked pore channels, which can promote electron transport and provide physical barrier and volume expansion space for polysulfides. Due to the combined effects of the US-Mo 2 C and KB, Li-S cells employing the multifunctional PP separators modified with KB/US-Mo 2 C composite (KB/US-Mo 2 C@PP) exhibit a high specific capacity (1212.8 mAh g −1 at 0.2 C), and maintain a reversible capacity of 1053.3 mAh g −1 after 100 cycles. More importantly, the KB/US-Mo 2 C@PP cells with higher sulfur mass loading of 4.9 mg cm −2 have superb areal capacity of 2.3 mAh cm −2 . This work offers a novel and promising perspective for high-performance Li-S batteries from both the shuttle effect and the complex polysulfides conversion.
研究领域:
材料科学
·
能源存储技术
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 14
·6054-6064
·
IF 9.931
Lechen Diao,Jian Qin,Naiqin Zhao,Chunsheng Shi,Enzuo Liu,Fang He,Liying Ma,Jiajun Li,Chunnian He
Hollow β-Mo2C/N-doped carbon composite nanospheres constructed by mesoporous ultrathin carbon nanosheets anchored with ultrasmall β-Mo2C nanoparticles were synthesized through a facile green process. Nanobubbles generated by ethanol–water exchange were utilized as templates for the core, while the precipitates in the solution were directly adopted as the emulsion stabilizer and the shell. Upon the self-polymerization of dopamine, a robust shell consisting of the Mo–polydopamine complex was formed. The size of the as-obtained hollow Mo–polydopamine nanospheres can be tuned by varying the type of gas, which is proportional to the supersaturation of gas. These precursors of hollow Mo–polydopamine nanospheres were then converted into hollow β-Mo2C/N-doped carbon composite nanospheres by high-temperature carbonization treatment. The N-doped carbon matrix can act as an electron conductor and facilitate the prevention of the migration and aggregation of the Mo2C nanoparticles, while the ultrafine Mo2C nanoparticles can achieve maximum material utilization for hydrogen evolution electrocatalysis. In addition, the mesoporous 2D nanosheets combined with their constructed 3D hollow structures can expose numerous active catalytic sites while enabling free diffusion of the electrolyte and mass transfer. As a result, the hollow β-Mo2C/N-doped carbon composite nanospheres exhibit low overpotentials and robust cycling stability in both acidic and alkaline electrolytes.
研究领域:
材料科学
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电化学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2024
·Vol. 12
·期 6
·3557-3564
·
IF 10.7
Lijuan Jiang,Ruijing Wang,Huimin Zhou,Guang-Feng Wei,Xuefeng Wang
Carbides have a high d-band electronic density of states at the Fermi level and hence characteristics resembling those of platinum. However, due to the strong adsorption of hydrogen intermediates on the surface of the carbides, the kinetics of the hydrogen evolution reaction (HER) is severely limited. Here, we demonstrate a strategy to improve the HER kinetics of carbides by modulating the surface electronic structure. Mo2C–W2C ultrafine nanoparticles on reduced graphene oxide (Mo2C–W2C/RGO) with strong electron interaction are constructed to improve the HER activity. The interfacial interaction between Mo2C and W2C adjusts the electronic structure of the surface, and the favorable hydrogen desorption on this surface is proved by density functional theory calculations. Benefitting from the adjusted electronic structures on the Mo2C–W2C heterointerface, the hydrogen adsorption free energies on both the Mo and W sites of Mo2C–W2C are close to the ideal values (0 eV). As expected, the Mo2C–W2C/RGO exhibits a superior HER activity with ultra-low overpotentials of 81 mV and 87 mV at a current density of −10 mA cm−2 under acidic and alkaline conditions, respectively, as well as remarkable stability. This work reveals the modulating effect of the electronic structure of carbides on the HER activity, which has a profound guiding effect for the directional design of advanced electrocatalysts.
研究领域:
材料科学
·
电催化
·
理论计算
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2022
·
IF 6.562
Mingsheng Luo,Chenmeng Li,Qinglong Liu,Zhi Yang,Yatao Wang,Hongjuan Li
Direct hydrogenation of CO to alcohols through Fischer-Tropsch reaction process is taken great interest in recent years. In this study, a series of β-Mo 2 C/γ-Al 2 O 3 catalyst are prepared to investigate the influence of carbon and molybdenum precursor, calcination temperature, as well as the molar ratio of the carbon precursor to molybdenum precursor compounds on catalyst microstructures and the catalytic performance. The microstructure characteristics of the catalysts were examined with XRD, BET, ICP, SEM and CO-TPD. The performance test of the catalysts for syngas-to-alcohol was investigated in a fixed-bed reactor. Properly excessive amount of hexamethylenetetramine as carbon precursor calcined at a high temperature (≥700 ℃) favors the formation of high crystalline β-Mo 2 C on γ-Al 2 O 3 carrier. Catalysts with different amount of Mo were prepared to study the effect of active metal loading on microstructure and catalytic performance. The results show that the particle size of β-Mo 2 C and CO dissociation adsorption capacity, as well as the CO conversion increases with raised Mo loading. The selectivity of all higher alcohols reached the maximum when 25 % of Mo was loaded.
研究领域:
催化
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化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
DIAMOND AND RELATED MATERIALS
·
2024
·
IF 4.3
Zhen Li,Xianhui Wang,Da Li,Hongbo Zhang,Bochen Zhang
The Mo 2 C@CNTs/Cu-20wt.%Mo composite materials with outstanding mechanical properties and electrical conductivity were prepared via the combination of mechanical wet-mixing, ball-milling and spark plasma sintering technology. By regulating the morphology and content of Mo 2 C decorated on CNTs, the Mo 2 C nanoparticles are anchored on CNTs and well bonded with the matrix, resulting the good interfacial bonding in the composite material. The Cu-20wt.%Mo composite material reinforced by 0.2wt.%Mo 2 C@CNTs exhibits a yield strength of 342.19 MPa and an ultimate tensile strength of 390.37 MPa, which are respectively increased by 23.13 % and 20.34 % as compared to the Cu-20wt.%Mo. Besides, the electrical conductivity of the 0.2wt.%Mo 2 C@CNTs/Cu-20wt.%Mo composite material is also improved by 6.89 %. Furthermore, the strengthening effect of Mo 2 C@CNTs/Cu-20wt.%Mo composite material can be attributed to the contribution of Mo 2 C nanoparticles, which not only enhance the CNTs load transfer strengthening but also promote the dislocation strengthening and Orowan strengthening.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
CARBON
·
2024
·
IF 10.5
Rui Xue,Di Lan,Rong Qiang,Zicheng Zang,Junwen Ren,Yulong Shao,Lei Rong,Junwei Gu,Jingbo Fang,Guanglei Wu
Dielectric-dielectric nanocomposites with excellent synergistic effects are considered as a prospective avenue for the development of high-performance microwave absorbers. In this work, one-dimensional MoO 2 /Mo 2 C/C heterogeneous nanowires were synthesized via a straightforward co-precipitation and in situ pyrolysis process. The components were modulated by adjusting the reduction temperatures to achieve tunable electromagnetic parameters thereby optimizing the dielectric loss. The results showed that the optimized MoO 2 /Mo 2 C/C composite exhibited a minimum reflection loss of −50.7 dB at an ultra-thin thickness of 1.8 mm and an effective absorption bandwidth of 6 GHz at 2.3 mm when the calcination temperature was 700 °C. Based on the studies of electromagnetic parameters and radar cross section simulation outcomes, both the interwoven one-dimensional structure and synergistic effects between the components have endowed the material with good impedance matching and introduced various loss mechanisms such as conductivity loss, multiple polarization relaxation, and multiple reflection/scattering. This work presented a viable strategy for the preparation of one-dimensional MoO 2 -based dielectric microwave absorption materials.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2024
·
IF 3.9
Sihui He,Hao Qu,Jiadong Liu,Jian Sun,Yue Su,Ruijue Hu,Yulong Zhang,Haiquan Su
Higher alcohols synthesis (HAS) is an important branch of syngas conversion, and Mo 2 C-based catalyst is a promising system for this reaction. However, the CO conversion and alcohols selectivity of current Mo 2 C-based catalysts are still low, which hinders their industrial application. Here, a series of Mo 2 C with three-dimensional hierarchically porous (3DHP) structures were prepared via a hard template method and their catalytic performance in HAS was investigated. The CO conversion and higher alcohols proportion of the optimal 3DHP catalyst were increased from 5.1 % and 60.4 % to 17.6 % and 70.5 %, respectively, compared with that of bulk Mo 2 C under similar total alcohols selectivity. The enhancement of the catalytic performance could be related to the increased number of active sites and the synergistic effect between multivalent Mo species. Additionally, the optimal 3DHP catalyst demonstrated good stability over a period of 200 h. This study provides a potential application for 3DHP materials and an alternative for designing efficient Mo 2 C catalysts for the HAS reactions.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2018
·Vol. 47
·期 41
·14767-14773
·
IF 4.099
Sisi Dai,Bin Quan,Baoshan Zhang,Xiaohui Liang,Guangbin Ji
In this work, novel one-dimensional (1D) Mo2C/Co@C nanorods (MCRs), using a metal–organic framework (zeolitic imidazolate framework; ZIF-67) as the coating layer to form multi-interfaces, were formed via a facile hard template method. Compared with previous works relating to porous-carbon-based Mo2C nanocomposites, the well-designed MCRs in this study possess a double attenuation mechanism due to the existence of the dielectric materials Mo2C and remaining carbon (RC) and the magnetic compound Co. Thanks to a new design and the multiple useful compounds, the as-prepared MCRs have the features of demonstrating multi-interfacial polarization, a large surface area and highly isotropic dissipation. Hence, the samples not only inherit the excellent microwave absorbing abilities of Mo2C but they also have a broadened effective bandwidth. For example, the minimum reflection loss (RL) value of MCRs with 35% sample loading could reach −47.98 dB. More importantly, RL values of less than −10 dB can be observed from 11.08 to 17.08 GHz (an effective bandwidth of 6.0 GHz) with a matching thickness of 1.6 mm, which is much better than previous work involving porous-carbon-based Mo2C nanocomposites. Firstly, we have reasonably redesigned the samples to have good absorbing properties for practical applications. Secondly, we have paved a highly efficient and universal way to synthesize 1D microwave absorbers with multiple valuable interfaces.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）