ENERGY & FUELS
·
2020
·
IF 3.421
Chunhao Wang,Xiang Xu,Yang Guo,Fan Zhou,Hongyu Chen,Haoyang Li,Zheng Zeng,Liqing Li
The cobalt carbide (Co2C) innovatively prepared from Co–Mn layered double hydroxide (CoMn LDH) has been investigated and evaluated toward its alternative synthesis conditions and different catalytic performances. Along with various characterization techniques, the preparation basically contains four steps (synthesis of CoMn LDH, calcination, reduction, and crystallization) that transform CoMn LDH to CoMn spinel and then to Co2C. Catalyst evaluation toward toluene pyrolysis was conducted. The sample with Co2C exhibited almost 100% conversion rate of toluene, where the resulting hydrogen yield (∼1.8%) is 6 times more than that of the blank test by using silica sand (∼0.3%), realizing the full transfer of hydrogen element from toluene to hydrogen molecule. Furthermore, based on the textural analysis and density functional dispersion correction calculation, which theoretically explained the easy accessibility of toluene to the crystal surface of Co2C(001) with a relatively high adsorption energy (about −280 kJ mol–1), it suggested that Co2C may expand more extensive applications in the field of catalysis.
研究领域:
材料科学
·
催化化学
✓ 已验证
DOI
高影响因子
Journal of Energy Chemistry
·
2021
·
IF 9.676
Genlin Liu,Cheng Yuan,Pan Zeng,Chen Cheng,Tianran Yan,Kehua Dai,Jing Mao,Liang Zhang
Utilizing catalysts to accelerate the redox kinetics of lithium polysulfides (LiPSs) is a promising strategy to alleviate the shuttle effect of lithium–sulfur (Li–S) batteries. Nevertheless, most of the reported catalysts are only effective for LiPSs reduction, resulting in the devitalization of catalysts over extended cycles as a consequence of the continuous accumulation of Li 2 S passivation layer. The situation gets even worse when employing mono-directional catalyst with poor electron conductivity because the charge transfer for the decomposition of solid Li 2 S is severely hampered. Herein, a high-conductive and dual-directional catalyst Co 3 C decorated on porous nitrogen-doped graphene-like structure and carbon nanotube (Co 3 C@PNGr-CNT) is fabricated as sulfur host, which not only promotes the precipitation of Li 2 S from LiPSs during discharge but also facilitates the decomposition of Li 2 S during subsequent charge, as evidenced by the reduced activation energies for both reduction and oxidation processes. Furthermore, the long-term catalytic stability of Co 3 C is corroborated by the reversible evolution of Co–C bond length over extended cycles as observed from X-ray absorption fine structure results. As a consequence, the fabricated Co 3 C@PNGr-CNT/S cathode delivers a low capacity decay of 0.043% per cycle over 1000 cycles at 2C. Even at high sulfur loading (15.6 mg cm −2 ) and low electrolyte/sulfur (E/S) ratio (∼8 μL mg −1 ) conditions, the battery still delivers an outstanding areal capacity of 11.05 mAh cm −2 after 40 cycles. This work provides a rational strategy for designing high-efficient bidirectional catalyst with single component for high-performance Li-S batteries.
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Xiaodan Zhang,Fei Yu,Jie Zhang,Zhiyong Tang,Yuhan Sun
Wall-coating is an attractive approach for immobilizing catalyst into microchannels due to potential enhancement in heat and mass transfer and a small pressure drop. A novel hybrid method was thus developed for efficiently wall-coating special cobalt carbide catalyst into FeCrAlloy microchannels on the direct production of lower olefins from syngas. The effect of pretreatment was investigated to form a uniform Al2O3 layer on the surface of FeCrAlloy substrate. The small loss of coated catalyst layer in the mechanical adherence test by exposing the FeCrAlloy substrate to a fast nitrogen flow indicated its outstanding stability in the immobilization of cobalt carbide catalyst. The coating catalyst exhibited a stable and good activity after reaching the steady state. Additionally, calculations revealed that the wall-coated and fixed-bed microreactors had comparable mass transfer factor jD, but the former provided a five times larger heat transfer factor jH and 100 times lower pressure drop per unit length, confirming in detail the advantages of wall-coating. The proposed wall-coating strategy can be applied for immobilizing other catalyst within metallic microchannels, providing a practical technical solution for industrial implementation of microreactors.
研究领域:
化学工程
·
催化材料
✓ 已验证
DOI
高影响因子
ADVANCED MATERIALS
·
2024
·Vol. 36
·期 35
·2404046
·
IF 27.4
Xiaoling Hong,Qiao Zhao,Yanping Chen,Zhibin Yu,Mengzhen Zhou,Yan Chen,Wenhao Luo,Chang Wang,Na Ta,Haitao Li,Runping Ye,Xiaotao Zu,Wei Liu,Jian Liu
Cobalt carbide (Co 2 C) possesses high catalytic efficiency Fischer–Tropsch synthesis (FTS), while the products selectivity appears sensitive to crystallography geometry. Since the Anderson–Schulz–Flory (ASF) distribution in FTS is broken through fabricating facetted Co 2 C nanocrystals, yet the underlying mechanism of Co 2 C crystallization remains unclarified suffering from sophisticated catalyst composition involving promoter agents. Herein, the synthesis of high-purity single-crystal nanoprisms (Co 2 C-p) for highly efficient FTS is reported to lower olefins. Through comprehensive microstructure analysis, e.g., high-resolution TEM, in situ TEM and electron diffraction, as well as finite element simulation of gas flow field, for the first time the full roadmap of forming catalytic active cobalt carbides is disclosed, starting from reduction of Co 3 O 4 precursor to CoO intermediate, then carburization into Co 2 C-s and subsequent ripening growth into Co 2 C-p. This gas-induced engineering of crystal phase provides a new synthesis strategy, with many new possibilities for precise design of metal-based catalyst for diverse catalytic applications.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Nano Materials
·
2019
·
IF 0
Sefiu Abolaji Rasaki,Hangjia Shen,Tiju Thomas,Minghui Yang
Transition metal carbides have received significant attention for oxygen reduction reaction (ORR) applications primarily owing to their good conductivity. However, cobalt carbide based catalysts (CoCx) are difficult to prepare, owing to the preferential formation of metallic cobalt and cobalt oxide instead. Also, cobalt carbide nanoparticles rapidly coarsen and undergo grain growth. This is a problem as it results in low current density and poor active site exposures. In this study, carbon-supported CoCx (C@CoCx) is successfully synthesized using the solid–solid separation synthesis method. The limitations identified to be associated with cobalt carbide nanoparticle based electrocatalysts are overcome. Here, the synthetic approach ensures good distribution and protection of CoCx on in situ generated carbon nanotubes. This results in robust activities with an appreciable onset potential of ∼0.92 V, a half-wave potential of ∼0.8 V, and a durability of ∼100% (tested on ∼22 h continuous operation runs). In alkaline medium, C@CoCx compares favorably with commercial platinum dispersed on carbon (20 wt % Pt/C) and shows a higher current density of ∼300 μA/cm2 at an electrode potential of 0.6 V. All of these indicate that there is a synergistic charge transfer between CoCx and an in situ generated carbon nanotube. This is due to intimate contact that exists between the two phases; it is in fact responsible for superior methanol tolerance observed, making it a good candidate for direct methanol fuel cells.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Fang Li,Haili Lin,Huiqin Yu,Xuemei Jia,Shifu Chen,Jing Cao
Replacing the sluggish oxygen evolution reaction with the oxidation of benzyl alcohol to construct the hybrid water electrolysis system has been attractive for its merits of environmentally friendly and economically efficient. However, the activity of the catalyst to oxidize alcohols needs to be further improved. Tailoring the d-band center (E d ) has been proven as an effective method to promote the hydrogen evolution reaction (HER). How feasible is this strategy in the oxidation of benzyl alcohol? Here, using Co 2 C as a research platform, the doping nonmetal heteroatom (P, S, N) engineering is adopted to promote its electrocatalytic BA oxidation and HER performance. The results of electrochemical tests show that the P-doped Co 2 C (P–Co 2 C) only requires a low potential of 1.33 and 1.38 V vs. RHE to achieve current densities of 20 and 100 mA cm −2 for BA oxidation, which is superior to that of S–Co 2 C, N–Co 2 C, and pristine Co 2 C. The conversation and faradaic efficiency for BA is up to 98.1% and 93.8% during ten consecutive cycle tests. The P–Co 2 C also exhibited outstanding activity and stability toward HER. The density functional theory (DFT) calculation revealed that specified P doping could modify the d-band center of Co 2 C approaching the peak of the volcano map (electrochemical overpotentials ∼ E d ). The Gibbs free energy of the BA oxidation was also reduced, thus optimizing the adsorption and desorption process of intermediates. On the other hand, the catalyst surface physical properties of Co 2 C such as hydrophilicity was promoted by the doped heteroatoms which was favorable for the gas-liquid-solid triphase electrocatalytic reaction. This work offers a facial perception of regulating the d-band to design advanced bifunctional electrocatalysts for organic matter oxidation and HER.
研究领域:
电化学
·
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Minhua Zhang,Haipeng Yu,Yuzhe Sun,Yingzhe Yu,Yifei Chen,Lingtao Wang
Cobalt carbide (Co 2 C) has been discovered as the promising active phase for Fischer–Tropsch to olefins (FTO) process and higher alcohols synthesis (HAS) from syngas, in the form of nanoprisms and nanospheres, respectively. However, CO 2 formation is inevitable on Co 2 C catalysts, especially in FTO process. So far, the mechanism of CO 2 formation on Co 2 C surfaces is less understood. This work provides fundamental insights into CO 2 formation on Co 2 C nanospheres and nanoprisms through computational and experimental study. DFT calculations demonstrate that: Co 2 C (1 0 1) and (0 2 0) surfaces exposed on Co 2 C nanoprisms are basically not active for water gas shift (WGS) reactions but the introduction of Na greatly promotes CO 2 formation. CO 2 is less favored on Co 2 C(1 1 1) surface which is dominant on Co 2 C nanospheres, however, the reverse WGS activities can be promoted with Na addition. The experimental results confirmed removing Na from Co 2 C can efficiently suppress WGS activity, thus reducing CO 2 selectivity while the selectivity of light olefins retained. Though previous studies focused on Na addition to promote the yield of light olefins, our work indicates that Na also promotes undesired CO2 formation. Our results suggest that Na is crucial for active phase formation but not necessarily beneficial during the CO hydrogenation reactions.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2018
·
IF 3.525
Xinxing Wang,Wen Chen,Tiejun Lin,Jie Li,Fei Yu,Yunlei An,Yuanyuan Dai,Hui Wang,Liangshu Zhong,Yuhan Sun
ABSTRACT Co 2 C-based catalysts with SiO 2 , γ-Al 2 O 3 , and carbon nanotubes (CNTs) as support materials were prepared and evaluated for the Fischer-Tropsch to olefin (FTO) reaction. The combination of catalytic performance and structure characterization indicates that the cobalt-support interaction has a great influence on the Co 2 C morphology and catalytic performance. The CNT support facilitates the formation of a CoMn composite oxide during calcination , and Co 2 C nanoprisms were observed in the spent catalysts, resulting in a product distribution that greatly deviates from the classical Anderson-Schulz-Flory (ASF) distribution, where only 2.4 C% methane was generated. The Co 3 O 4 phase for SiO 2 - and γ-Al 2 O 3 -supported catalysts was observed in the calcined sample. After reduction, CoO, MnO, and low-valence CoMn composite oxide were generated in the γ-Al 2 O 3 -supported sample, and both Co 2 C nanospheres and nanoprisms were identified in the corresponding spent catalyst. However, only separated phases of CoO and MnO were found in the reduced sample supported by SiO 2 , and Co 2 C nanospheres were detected in the spent catalyst without the evidence of any Co 2 C nanoprisms. The Co 2 C nanospheres led to a relatively high methane selectivity of 5.8 C% and 12.0 C% of the γ-Al 2 O 3 - and SiO 2 -supported catalysts, respectively. These results suggest that a relatively weak cobalt-support interaction is necessary for the formation of the CoMn composite oxide during calcination, which benefits the formation of Co 2 C nanoprisms with promising catalytic performance for the sustainable production of olefins via syngas.
研究领域:
化学工程
·
催化科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS RESEARCH BULLETIN
·
2024
·
IF 5.3
Haoliang Wen,Bo Lei,Weidong Zhang
The rational design of hollow-structured composite absorbing materials is emerging as a promising approach for enhancing microwave performance. The present study successfully synthesized a series of ZIF-67/MoS 2 composites with adjustable size range using a two-step method and achieved the formation of magnetically responsive Co/C/MoS 2 hybrids through high temperature pyrolysis. The findings demonstrated that ZIF-67/MoS 2 (1:12) exhibited a wide effective attenuation bandwidth (EAB) (5.60 GHz from 12.40 GHz to 18.0 GHz) with a thickness of 2.4 mm, and minimum reflection loss (−43.46 dB) at 2.1 mm. However, Co/C/MoS 2 hybrid possessed the better EAB (5.95 GHz from 11.61 GHz to 17.56 GHz) at 1.2 mm and minimum reflection loss (−51.83 dB) at a thickness of 1.0 mm. The ingeniously synthesized ZIF-67/MoS 2 and Co/C/MoS 2 composites, hence, unravel themselves as a promising and exceedingly efficient contender for lightweight microwave absorption.
研究领域:
材料科学
·
电磁学
✓ 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）