Journal of Energy Storage
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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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Catalysis Science & Technology
·
2021
·Vol. 11
·期 11
·3706-3714
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IF 6.119
Lekai Zheng,Lina Hu,Yongchuan Hu,Fang Liu,Zhiming Liu,Yanming Xue,Jun Zhang,Hui Liu,Chengchun Tang
The development of efficient, stable and low-cost oxygen evolution reaction (OER) catalysts in anodes is essential for the production of hydrogen resources by electrolyzing water. Cobalt hydroxide (α-Co(OH)2) is one of the most encouraging electrocatalysts for the OER under alkaline conditions, but its catalytic activity is still unsatisfactory possibly due to its unfavorable electronic structure. The construction of heterogeneous catalysts has been considered as an effective strategy to change the interface and modulate the electronic structure of electrocatalysts, resulting in improved activities. Herein, novel self-supported α-Co(OH)2 coated Co3O4 nanosheet arrays on conductive carbon cloth have been constructed and fabricated via a simple electrodeposition method (α-Co(OH)2/Co3O4/CC), serving as efficient catalysts for the OER. The as-prepared heterostructure with optimal proportions of α-Co(OH)2 to Co3O4 exhibits an enhanced overpotential of 275 mV at 10 mA cm−2 (322 mV for α-Co(OH)2/CC and 359 mV for Co3O4/CC), a low Tafel slope of 76 mV dec−1 and excellent durability for 22 h. The further electrochemical results show that the formation of heterostructure can optimize the electronic structure of the catalysts through interfacial coupling effect, improve the charge transfer ability and increase the electrochemical active sites, all of which are beneficial to the OER performance enhancement. This work not only develops a highly efficient and stable non-precious metal catalyst toward the OER, but also opens up new ways for boosting the performance by regulating the electronic structure through interface engineering of electrocatalysts and beyond.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2020
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IF 3.573
Jinwei Chen,Meng Huang,Wang Chen,Haiyan Tang,Yi Jiao,Jie Zhang,Gang Wang,Ruilin Wang
The inherent low activity at room temperature has greatly limited the utilization of Co3O4 in indoor air purification. In this work, an extremely facile and mild method utilizing the strong oxidation of H2O2 was designed to prepare a novel Co3O4-HP catalyst. The Co3O4-HP catalyst exhibits excellent removal activity for low-level concentration (∼1 ppm) of formaldehyde (HCHO) at room temperature. Under the static test mode, it shows 90.62% HCHO removal efficiency in 180 min at an RH of ∼55%. Under the dynamic test mode, it maintains the performance to remove approximately 97.26% of HCHO within 180 min under a GHSV of ∼90,000 mL·h–1·g–1. Additionally, the HCHO removal efficiency of Co3O4-HP is also maintained at around 94.76% under a higher GHSV of ∼150,000 mL·h–1·g–1. Such a satisfying activity is due to abundant oxygen vacancy defects bringing about a large number of surface reactive oxygen species and high redox capacity and oxygen migration capacity. It is also because of the synergistic effect of surface OH groups. This strategy will open an exciting avenue to design outstanding catalysts for HCHO removal by defect engineering and the synergistic effect.
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APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Huanhuan Li,Mingyang Tan,Can Huang,Weiping Luo,Shuang-Feng Yin,Weijun Yang
Functional nanosheets have attracted great attention due to their potential applications in catalysis chemistry and material science. Herein, Co 3 O 4 nanoparticles interconnecting with nitrogen-doped carbon architectures (denoted as Co 3 O 4 /NC) was developed on nickel foam surface by a two-step solvothermal process and followed by calcination. A metal organic framework (MOF) of laminar CoMOF-NH 2 was synthesized firstly by in-situ transformation of Co 2 (OH) 3 Cl array. Then, porous Co 3 O 4 /NC nanosheets were obtained by controlled heat treatment of CoMOF-NH 2 . The Co 3 O 4 /NC supported by nickel foam can be directly used as self-supported electrodes for electrocatalysis without any binders. As-synthesized Co 3 O 4 /NC acts as effective catalysis for oxygen evolution reaction (OER). Interestingly, the optimized electrochemical efficiency for OER was achieved by Co 3 O 4 /NC nanosheet with overpotentials of 235 mV and 264 mV offering current densities of 10 mA/cm 2 and 100 mA/cm 2 , respectively. It also has a relatively low Tafel slope, which indicates the fast electron transfer kinetics of the catalyst. So Co 3 O 4 /NC nanosheet has great potential in replacing precious metal electrocatalysts in OER application.
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MICROCHIMICA ACTA
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2021
·Vol. 188
·期 2
·1-10
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IF 5.833
Zhou Xi,Wang Shuangling,Zhang Cong,Lin Yulong,Lv Jie,Hu Shuyang,Zhang Shanshan,Li Meng
A sensitive and rapid colorimetric biosensor has been developed for determination of amyloid-β peptide (Aβ) and study of amyloidogenesis based on the high peroxidase-like activity of porous bimetallic ZnO-Co 3 O 4 nanocages (NCs). Due to the high binding ability of Aβ monomer to ZnO-Co 3 O 4 NCs, the catalytic activity of ZnO-Co 3 O 4 NCs can be significantly suppressed by Aβ monomer. This finding forms the basis for a colorimetric assay for Aβ monomer detection. The detection limit for Aβ monomer is 3.5 nM with a linear range of 5 to 150 nM ( R 2 = 0.997). The system was successfully applied to the determination of Aβ monomer in rat cerebrospinal fluid. Critically, the different inhibition effects of monomeric and aggregated Aβ species on the catalytic activity of ZnO-Co 3 O 4 NCs enabled the sensor to be used for tracking the dynamic progress of Aβ aggregation and screening Aβ inhibitors. Compared with the commonly used thioflavin T fluorescence assay, this method provided higher sensitivity to the formation of Aβ oligomer at the very early assembly stage. Our assay shows potential application in early diagnosis and therapy of Alzheimer's disease (AD).
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JOURNAL OF ALLOYS AND COMPOUNDS
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2020
·
IF 4.65
Ji-Jun Dong,Chao Ma,Qiang Zhang,Wen-Long Bai,Zhi-Peng Cai,Se-Si Li,Zhen Zhang,Xue-Yan Wu,Xiao Wei,Kai-Xue Wang,Jie-Sheng Chen
Lithium-oxygen batteries (LOBs) with superior energy density are recognized as a promising next-generation energy storage device for electric vehicles. However, the morphology and particle size of Li 2 O 2 as well as the parasitic products Li 2 CO 3 give an essential impact on electrochemical properties . To address these issues, a free-standing Co 3 O 4 -NiO@Ni electrode with Co 3 O 4 -NiO heterostructure nanoneedle arrays on Ni foam was fabricated. The Co 3 O 4 -NiO heterostructure would control the morphology and size of Li 2 O 2 . The free-standing carbon-free electrode design would avoid the generation of Li 2 CO 3 . Ultrathin Li 2 O 2 film is preferentially generated within the Co 3 O 4 -NiO heterostructure nanoneedles during the discharge process. The film-like morphology of Li 2 O 2 would decrease the Li 2 O 2 /electrode interfacial resistance and charge overpotential, and enhance the discharge capacity. The free-standing Co 3 O 4 -NiO@Ni electrode exhibits an improved electrochemical performance with a high discharge specific capacity of 7905 mAh g −1 at 0.1 A g −1 and good cyclic stability of 120 cycles at 0.1 A g −1 with a cutoff capacity of 500 mAh g −1 . This work provides a new strategy for improving the electrochemical performance of LOBs through the morphology control of Li 2 O 2 .
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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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SEPARATION AND PURIFICATION TECHNOLOGY
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2020
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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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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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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2019
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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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INORGANIC CHEMISTRY
·
2019
·
IF 4.85
Dandan Wu,Runping Jia,Ming Wen,Shuai Zhong,Qingsheng Wu,Yongqing Fu,Shuhong Yu
A nanostructural catalyst with long-term durability under harsh conditions is very important for an outstanding catalytic performance. Herein, a new ultrastable PtCo/Co3O4–SiO2 nanocatalyst was explored to improve the catalytic performance of carbon monoxide (CO) oxidation by virtue of the surface active lattice oxygen derived from strong metal–support interactions. Such a structure can overcome the issues of Co3O4–SiO2 inactivation by water vapor and the Pt inferior activity at low temperature. Further, Co3O4–SiO2 nanosheets endow superior structure stability under high temperatures of up to 800 °C, which gives long-term catalytic cyclability of PtCo/Co3O4–SiO2 nanocomposites for CO oxidation. Moreover, the large specific surface areas (294 m2 g–1) of the nanosheet structure can expose abundant surface active lattice oxygen, which significantly enhanced the catalytic activity of CO oxidation at 50 °C over 30 days without apparent aggregation of PtCo nanoparticles after 20 cycles from 50 to 400 °C. It can be expected to be a promising candidate as an ultrastable efficient catalyst.
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