JOURNAL OF THE AMERICAN CERAMIC SOCIETY
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2020
·Vol. 103
·期 12
·6764-6779
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IF 3.502
Yongfeng Wu,Yunwang Zhong,Yan Guan,Chong Gu,Guangyu Shao,Benyang Shi,Zhiming Su,Binbin Xu,Zhaoju Yu,Anhua Liu
In this work, porous core-shell structured Co 2 Si@SiC/C/SiOC/SiO 2 /Co 3 O 4 nanoparticles were fabricated by a polymer-derived ceramic approach. The in situ formation of mesopores on the shell, microstructural, and phase evolution of resulting nanoparticles were investigated in detail. The obtained nanoparticles-paraffin composites possess a very low minimum reflection coefficient (RC min ) −60.9 dB, broad effective absorption bandwidth 3.50 GHz in the X-band and 15.5 GHz in the whole frequency range (from 2.5 to 18 GHz). The results indicate outstanding electromagnetic wave (EMW) absorbing performance among all the reported cobalt-based nanomaterials, due to the reasons as follows: (a) The unique core-shell structure as well as complex phase composition of SiC/C/SiOC/SiO 2 /Co 3 O 4 in the shell, result in a large number of heterogeneous interfaces in the nanoparticles; (b) Nanoparticles have both dielectric and magnetic loss; (c) Mesopores in the shell prolong the propagation path of EMW, thereby increasing the absorption/reflection ratio of EMWs. Thanks to the material structure design, the resulting core-shell structured cobalt-containing ceramic nanoparticles have great potential for thin and high-performance EMW absorbing materials applied in harsh environment.
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NEW JOURNAL OF CHEMISTRY
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2020
·Vol. 44
·期 26
·11042-11048
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IF 3.288
Yi Yang,Qiu Zhang,Fengyan Li,Zhinan Xia,Lin Xu
This paper reports for the first time the preparation of Co3O4 nanorods by simple hydrothermal and annealing methods, which are doped with polyoxometalates that act as an intermediary in electronic transmission to accelerate electron transport. The designed H3PW12O40(PW12)/Co3O4–Cu2S composite film was prepared by the screen printing method to boost its efficiency as the counter electrode for quantum dot-sensitized solar cells, where the preparation process is simple and inexpensive. PW12/Co3O4–Cu2S (Jsc = 16.60 mA cm−2, Voc = 0.636 V, Rct = 0.32 Ω and FF = 0.436) shows better electrocatalytic performance compared to the original Co3O4 and Cu2S. Accordingly, the photoelectric conversion efficiency of PW12/Co3O4–Cu2S is 4.67%, which is 10%, 46%, 55.6%, and 72% higher than those of Co3O4–Cu2S (4.2%), Cu2S (2.54%), PW12/Co3O4 (2.07%), and Co3O4 (1.30%), respectively. Electrochemical impedance spectroscopy and Tafel measurements performed on two CE symmetric virtual cells proved the excellent electrocatalytic activity of PW12/Co3O4–Cu2S. Therefore, this composite film can be used as an alternative option for QDSSC counter electrodes.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2020
·
IF 5.774
Zishun Li,Xuekun Tang,Ganghong Huang,Xianping Luo,Dongsheng He,Qian Peng,Jing Huang,Minlin Ao,Kun Liu
A hierarchical Co 3 O 4 -Bi 2 O 3 composite was first prepared via an adsorption-calcination method using a bismuth-based MOF (Bi-BTC) as the precursor and substrate. In the composite, Co 3 O 4 nanoparticles are loaded on the outer layer of Bi 2 O 3 rods derived from Bi-BTC and show a uniform honeycomb-like morphology. In dyes degradation tests, the Co 3 O 4 -Bi 2 O 3 composite exhibits much better peroxymonosulfate (PMS) activation performance in RhB degradation than pure Bi 2 O 3 or Co 3 O 4 . The Co 3 O 4 -Bi 2 O 3 /PMS system also shows high performance for various azo dyes and maintains good catalytic performance at wide pH range. Besides, the good chemical stability of Co 3 O 4 -Bi 2 O 3 ensures it good reusability in four recycling tests. XPS and electrochemical analysis indicate the interaction of Bi species promotes the activation capacity of Co 3 O 4 nanoparticles. The results of radicals quenching tests and ESR analysis reveal the singlet oxygen and superoxide radicals are the dominant functional radical species in Co 3 O 4 -Bi 2 O 3 /PMS system and subsequently a reasonable activation mechanism is proposed.
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CHEMICAL ENGINEERING JOURNAL
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2020
·
IF 10.652
Yulin Jiang,Chengen He,Shengqiang Qiu,Jinlong Zhang,Xianggang Wang,Yingkui Yang
Graphene/Co 3 O 4 composites have been considered as promising electrode materials for high-performance supercapacitors; however, their practical applications have been limited by the complex synthesis technologies and narrow potential window of around 0.5 V. Herein we report a facile and economical approach to the massive production of graphene/Co 3 O 4 composites through the one-pot ball-milling of graphite, (NH 4 ) 2 CO 3 , and Co(CH 3 COO) 2 . During the process, graphite was intercalated by (NH 4 ) 2 CO 3 and synchronously exfoliated into few-layer graphene sheets containing functional groups. Co 3 O 4 nanocrystals were then in-situ grown on the surface of graphene sheets via mechanochemical reactions between (NH 4 ) 2 CO 3 and Co(CH 3 COO) 2 . The as-prepared graphene/Co 3 O 4 composites exhibit a high specific capacitance of 570 F g −1 at 1 A g −1 , and retain 93% of initial capacitance when the current density is increased by 20 times. The excellent electrochemical performance can be attributed to the synergistic effect between the highly-conductive graphene and nanostructured Co 3 O 4 capable of accelerating the electron conduction and ion transport for increasing the capacitive contribution. Asymmetric supercapacitors were also assembled using graphene and graphene/Co 3 O 4 as negative and positive electrodes, respectively. The asymmetric devices demonstrate a wide operating potential window up to 1.6 V, thus achieving a high specific capacitance of 190 F g −1 at 1 A g −1 . Accordingly, the energy density is as high as 67.5 W h kg −1 at the power density of 0.8 kW kg −1 . This work provides an affordable and scalable approach to prepare graphene-based composites with metal oxides for high-performance electrode materials for electrochemical energy storage.
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Journal of Energy Storage
·
2021
·
IF 6.583
Lei Liu,Zijian Zhou,Changqing Wang,Jie Xu,Hongqiang Xia,Guozhang Chang,Xiaowei Liu,Minghou Xu
Co 3 O 4 has been regarded as one of the most promising materials for redox energy storage due to its high theoretical conversion and complete redox reversibility. However, when undergoing charge-discharge cycles at high temperature, the material becomes sintered. The reversibility of the cobaltous oxides highly deteriorates, and the reoxidation reaction rate notably decreases. In addition, the obvious thermal hysteresis in the redox reaction process also limits the energy storage performance of the material. In this work, Co 3 O 4 with different micro-nanostructured morphologies is synthesized to evaluate its thermochemical energy storage performance. The capacity of the synthesized and commercial Co 3 O 4 is tested by thermogravimetric analysis (TGA). The fresh and recycled oxides are well characterized. Results suggest that all samples show complete reversibility, and the conversion decreases slightly after 30 cycles. The synthesized samples show better performance, especially cubic Co 3 O 4 . The reoxidation rate of the commercial sample is approximately 150 μmol/min/g, but that of the cubic sample is approximately 300-200 μmol/min/g in the first five cycles. The oxidation rate of the cubic sample decreases and finally remains at about 180 μmol/min/g from the 5th cycle to the 30th cycle. After 5 charge-discharge cycles, the commercial Co 3 O 4 is severely sintered, while the cubic oxides are only slightly sintered. After 30 redox cycles, the morphology of commercial oxides completely changed, while that of the cubic oxide retains the approximate shape of a cube. Moreover, the thermal hysteresis values of the commercial and cubic Co 3 O 4 are 24.7°C and 10.1°C, respectively, suggesting that the energy loss of cubic oxides is much smaller. The higher exothermic temperature of the cubic Co 3 O 4 redox process also indicates that it can supply high-grade thermal energy.
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CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Yanling Chen,Xue Bai,Yetong Ji,Ting Shen
A novel reduced graphene oxide-supported hollow Co 3 O 4 @N-doped porous carbon (Co 3 O 4 @NPC/rGO) composite was synthesized via self-assembly and pyrolysis-oxidation using bimetallic zeolite imidazolate frameworks and graphene oxide as precursors. The as-obtained composite exhibited superior performance on peroxymonosulfate (PMS) activation over a wide pH range. Complete removal of sulfamethoxazole (SMX, 25 mg·L −1 ) was achieved within 5 min and the reaction rate constant was higher than those of the most reported heterogeneous catalyst/PMS systems for SMX degradation. It was demonstrated that both radical pathways (SO 4 − , OH, and O 2 − ) and non-radical pathways ( 1 O 2 and direct electron transfer) were involved in the SMX degradation. Significantly, the contribution ratio of each reactive oxidative species (ROS) in the bulk solution or on the catalyst surface was differentiated and calculated for the first time. SO 4 − both in the bulk solution and on the catalyst surface as well as the 1 O 2 in the bulk solution were the dominant ROS. The possible degradation mechanism of SMX by Co 3 O 4 @NPC/rGO/PMS system was proposed. Co active sites with high activity, the electron-rich ketonic group and the nitrogen doping sites within Co 3 O 4 @NPC/rGO contributed to the excellent catalytic activity. The ecotoxicity of SMX and its intermediates was investigated. Besides, the reusability, stability and application potential in actual waterbodies of Co 3 O 4 @NPC/rGO were evaluated. Overall, this work expands the environmental application of metal–organic frameworks (MOFs)-derived hollow nanomaterials and provides a promising heterogeneous catalyst for the elimination of refractory contaminants by sulfate radical-based advanced oxidation processes (SR-AOPs).
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APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Jiaqi Chen,Lili Zhang,Jingwen Sun,Junwu Zhu,Xin Wang,Yongsheng Fu
Ingenious design of catalysts structure is vital for accelerating ammonium perchlorate (AP) thermal decomposition at lower temperature and accompanying with more heat release. In this work, a self-templated approach is adopted to construct hierarchical hollow double-shelled Co 3 O 4 using cobalt glycerate solid spheres as precursors. The structural transformation from the solid species to the hollow double-shelled Co 3 O 4 sphere is implemented by a solution growth combined with a subsequent calcination . The hierarchical hollow double-shelled morphology, large surface area and unique electronic structure endue Co 3 O 4 with enhanced catalytic performance for thermal decomposition of AP. The AP decomposition temperature is decreased to 318 °C and heat release is increased from 491 J g −1 to 1280 J g −1 .
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2021
·
IF 9.028
Ying Xiong,Yumei Zhao,Xingkun Qi,Jiayi Qi,Yuanyuan Cui,Haibiao Yu,Ying Cao
In this paper, Gd-promoted Co3O4 catalysts were prepared via a facile coprecipitation method for low-temperature catalytic N2O decomposition. Due to the addition of Gd, the crystallite size of Co3O4 in the Gd0.06Co catalyst surprisingly decreased to 4.9 nm, which is much smaller than most additive-modified Co3O4 catalysts. This huge change in the catalyst’s textural structure endows the Gd0.06Co catalyst with a large specific surface area, plentiful active sites, and a weak Co–O bond. Hence, Gd0.06Co exhibited superior activity for catalyzing 2000 ppmv N2O decomposition, and the temperature for the complete catalytic elimination of N2O was as low as 350 °C. Meanwhile, compared with pure Co3O4, Ea decreased from 77.4 to 46.8 kJ·mol–1 and TOF of the reaction increased from 1.16 × 10–3 s–1 to 5.13 × 10–3 s–1 at 300 °C. Moreover, Gd0.06Co displayed a quite stable catalytic performance in the presence of 100 ppmv NO, 5 vol % O2, and 2 vol % H2O.
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PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2019
·
IF 7.65
Wei Li,Yuxin Li,Deyun Zhang,Yeqing Lan,Jing Guo
CuO-Co 3 O 4 @CeO 2 nanoparticles used as a heterogeneous catalyst were prepared via a sol-gel method and characterized by various techniques. For comparison, a series of oxides was investigated for activating peroxymonosulfate (PMS) during the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D). The results indicated that CuO-Co 3 O 4 @CeO 2 exhibited the highest catalytic performance among the catalysts. Complete degradation of 2,4-D (20 mg/L) was realized within 45 min at 1 mM PMS, CuO-Co 3 O 4 @CeO 2 loading of 0.07 g/L, and pH of 6. Recycling experiments confirmed that CuO-Co 3 O 4 @CeO 2 was very stable, and the 2,4-D degradation efficiencies ranged from 100% to 97.5%, decreasing by only 2.5% after the fifth run. The outstanding catalysis of CuO-Co 3 O 4 @CeO 2 resulted from the synergy of cerium, cobalt, and copper. Electron paramagnetic resonance and radical scavenger experiments confirmed the production of SO 4 • − and • OH radicals in the CuO-Co 3 O 4 @CeO 2 /PMS system, which were responsible for efficient decomposition of 2,4-D. Furthermore, the combination of CuO-Co 3 O 4 @CeO 2 andPMS was applied to treat natural water containing 2,4-D, and a high 2,4-D removal rate was also achieved. Based on these results, it was deduced that CuO-Co 3 O 4 @CeO 2 can be utilized as a catalyst to activate PMS and destroy organic contaminants in aqueous solution.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2019
·
IF 3.218
Sumbal Farid,Weiwei Qiu,Jialin Zhao,Xuedan Song,Qing Mao,Suzhen Ren,Ce Hao
In recent years, a noticeable shifting from conventional fossil fuels to renewable energy based systems has embarked electrochemical splitting of water as the most promising way to produce clean energy of hydrogen. Generally, the lack of active and stable electrocatalysts for oxygen evolution reaction (OER) limits the practicability of water splitting as a renewable source of energy. In this work, interconnected 3D structure of cobalt oxides nanoparticles (Co 3 O 4 NPs) derived from ZIF-67 with nitrogen-doped carbon nanotubes (N-CNTs) of polypyrrole (PPy) origin is successfully synthesized as OER electrocatalysts. Impressively, the highly conductive N-CNTs that run through the Co 3 O 4 NPs not only endow the resulting product Co 3 O 4 /N-CNTs with large active surface area and enhanced charge transfer between Co 3 O 4 NPs, but also prevent Co 3 O 4 NPs from aggregation. As a result, the as-synthesized Co 3 O 4 /N-CNTs electrocatalyst exhibits outstanding OER activity with a low onset potential of ~1.37 V (vs RHE), overpotential of only 200 mV to attain a stable current density of 10 mA cm − 2 in basic media and very small Tafel slope of 40 mV dec − 1 . Moreover, the enhanced nitrogen-content also improves the OER kinetics by proficient charge transfer. The superb electrocatalytic performance and higher stability make the Co 3 O 4 /N-CNTs a proficient non-precious electrocatalyst for the OER.
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Nanoscale
·
2019
·Vol. 11
·期 12
·5285-5294
·
IF 6.97
Yunzhao Liu,Xiaowei Chi,Qi Han,Yuexiu Du,Jiaqi Huang,Xinghao Lin,Yu Liu
The Na–O2 battery system is attracting increasing attention due to its superiority in specific capacity and cost. However, its practical implementation is hindered by many issues, such as high charge–discharge overpotential, limited cycling life, and poor reversibility, all of which result from the mediocre O2 electrode. Herein, to surmount these critical challenges, hierarchical Co3O4@MnCo2O4.5 nanocubes (h-Co3O4@MnCo2O4.5 Ns) with a yolk–shell structure are designed for the first time as the novel O2 electrode. h-Co3O4@MnCo2O4.5 Ns are synthesized from a metal–organic framework via a template-assisted method, which is demonstrated to be helpful in creating a high specific surface area of 130.4 m2 g−1, a hierarchical macro- and mesoporous structure, and synergistic yolk-shelled Co3O4@MnCo2O4.5 active sites. These unique structural properties endow h-Co3O4@MnCo2O4.5 Ns with remarkably enhanced electrocatalytic activity towards both the ORR and OER. The Na–O2 battery based on h-Co3O4@MnCo2O4.5 Ns displays an ultrahigh initial discharge capacity of 8400 mA h g−1, ultralow charge–discharge overpotential of 0.45 V, long cycling life of 135 cycles, and excellent rate capability.
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Nano Energy
·
2019
·
IF 15.548
Zirui Lou,Dachao Yuan,Fengyu Zhang,Yichen Wang,Yaguang Li,Liping Zhu
CO oxidation is one of the most important catalytic reactions and it has to be run at relatively high temperature. Photothermal catalysis system could convert light as heat to drive CO oxidation rather than their conventional counterparts that use only thermal stimulus. But the light intensity required in this photothermal catalysis system is much higher than the solar intensity, restricting the application of photothermal CO oxidation. Here we present a Fe 3 Si based photothermal converted system to assist Co 3 O 4 rhombus-shaped nanorods catalysts for achieving efficient photothermal CO oxidation just under weak solar irradiation . Based on photothermal experiments, we conclude that Fe 3 Si based photo-thermal converted system can convert 0.3–0.35 kW m −2 solar irradiation into a temperature as high as 160 °C, 3 times higher than existing photothermal catalytic systems , which able to excite the activity of Co 3 O 4 rhombus-shaped nanorods for complete CO oxidation, solely irradiated by third of standard solar light and outdoor sunlight. The results suggested that the photothermal CO oxidation can be driven by ambient solar irradiation in the presence of Fe 3 Si based photothermal system and Co 3 O 4 rhombus-shaped nanorods, facilitating for industrial applications.
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