CARBON
·
2021
·
IF 9.594
He Yu,Cong Wang,Fanyi Meng,Jin Xiao,Junge Liang,Hyunseok Kim,Sanghoon Bae,Danqing Zou,Eun-Seong Kim,Nam-Young Kim,Meng Zhao,Baoqiang Li
This research investigates a microwave transduction-based humidity sensor that is a promising candidate for real-time clinical healthcare applications and green miniaturized wearable electronic devices. Optimization of sensing material, sensing platform, and device fabrication techniques produces a carbon dots (CDs)-decorated metal organic framework (MOF)-derived porous Co 3 O 4 (CDs-Co 3 O 4 ) microwave resonator-based sensor with excellent real-time humidity detection. Inspired by the water absorption component polyacrylamide in baby diapers, the acrylamide is adopted to synthesize CDs for microwave humidity sensor. Combining CDs with MOF-derived porous Co 3 O 4 enhances humidity sensitivity under microwave excitation, with a frequency shift of 3.40 MHz/% RH and a loss variation of 0.15 dB/% RH between 5% and 99% RH. These values are 49.7% (for frequency shift) and 20.5% (for return loss) higher than Co 3 O 4 sensor. Moreover, CDs-Co 3 O 4 exhibits high selectivity towards water vapor against other volatile organic compounds, and the response or recovery time are both less than 5 s. Fabricated by an integrated passive device technology, the sensing platform is miniaturized at 0.98 × 0.80 × 0.22 mm 3 with superb device stability and reliability. The CDs-Co 3 O 4 sensor remarkably monitors respiratory patterns of breathing or apnea, as well as subtle changes in the humidity levels of an approaching finger. A charge transfer process and microwave interactions are the mechanisms for improved humidity sensitivity.
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ACS Sustainable Chemistry & Engineering
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2020
·
IF 7.632
Mei Li,Shengbo Zhang,Liwen Li,Jinyu Han,Xinli Zhu,Qingfeng Ge,Hua Wang
The facile synthesis of low-cost, eco-friendly photocatalysts with high charge separation efficiency and CO2 adsorption capacity for efficient photocatalytic CO2 reduction remains a challenge. Herein, a hollow structured p-n heterojunction catalyst, polydopamine (PDA)-ZnO/Co3O4, was successfully synthesized by pyrolyzing bimetallic ZnCo-ZIFs, followed by modification with PDA. Through optimizing the Zn/Co ratio, a high separation efficiency of the photogenerated electron–hole pairs has been achieved. Furthermore, by tuning the content of PDA on the surface of ZnO/Co3O4, the adsorption capacity of CO2 can be maximized. Consequently, PDA15/ZnO/Co3O4 showed a CO production rate of 537.5 μmol/g/h with a CO selectivity of 97.7% without using the photosensitizer and additional sacrificial agent. Band structure based on results of X-ray photoelectron spectroscopy, photoelectrochemical characterization, as well as density functional theory calculation was used to propose a plausible mechanism for photocatalytic CO2 reduction on the PDA15/ZnO/Co3O4. The present study provides an effective approach to fabricate highly efficient photocatalysts based on semiconducting metal oxides for CO2 reduction with remarkable abilities of absorbing lights, separating charge carriers, and adsorbing CO2.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2020
·
IF 5.774
Ran Tian,Haoran Dong,Jie Chen,Rui Li,Qianqian Xie
In this study, amorphous Co 3 O 4 nanoparticles-decorated biochar was synthesized and employed to activate peroxymonosulfate (PMS) for sulfamethazine (SMT) degradation in aqueous solution. Hydrochar of corn straw obtained from hydrothermal carbonization was impregnated in CoCl 2 solution for anchoring cobalt nanoparticles onto biochar surface before pyrolysis. Application conditions of as-prepared cobalt-loaded biochar (Co-BC) involving dosage, pyrolysis temperature, cobalt loading, solution pH and groundwater components were examined; and the stability of the catalyst was investigated by examining its performance in recycling experiments (3 rounds) and the variation of catalytic mechanism in recycling experiment was investigated. 100% SMT was removed under the optimum condition within 60 min: 1.0 mmol/L CoCl 2 aqueous solution, 800 °C of pyrolysis temperature, 400 mg/L Co-BC, 0.06 mM PMS, solution pH 8. The results turned out that the amorphous Co 3 O 4 nanoparticles were favorable for the activation of PMS. BC not only played as a support for dispersion of Co 3 O 4 nanoparticles but also acted as an electron shuttle between Co 3 O 4 and PMS/SMT molecules. During the recycling use, the key free radicals changed from ▪OH and SO 4 ▪- to SO 4 ▪- and only low degree of cobalt ions leaching was monitored. Additionally, the mixed groundwater components exerted trivial influence on the reaction system.
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Nanoscale
·
2020
·Vol. 12
·期 7
·4374-4382
·
IF 6.895
Xingmei Guo,Cheng Qian,Xiaohan Wan,Wei Zhang,Haowei Zhu,Junhao Zhang,Hongxun Yang,Shengling Lin,Qinghong Kong,Tongxiang Fan
Streptococcus thermophilus, a Gram-positive (G+) bacterium featuring a teichoic acid-rich cell wall, has been employed as both a phosphorus source and template to synthesize a biomorphic Co2P-Co3O4/rGO/C composite as an efficient electrocatalyst for the oxygen reduction reaction (ORR). Different from the conventional method for the synthesis of phosphides, bio-derivative phosphorus vapor was emitted from the inside out, which facilitated the in situ transformation of the chemically adsorbed Co precursor on the bacteria into Co2P-Co3O4 heterogeneous nanoparticles, which featured a Co2P-rich body and Co3O4-rich surface. Besides, reduced graphene oxide (rGO) was also introduced in the synthetic process to keep Co2P-Co3O4 scattered and further promote the electron transport efficiency. All the Co2P-Co3O4 nanoparticles and rGO sheets were supported on the bacteria-derived carbon substrate with submicron-spherical morphology. The as-obtained Co2P-Co3O4/rGO/C composite exhibited excellent electrocatalytic performance for ORR with onset and half-wave potentials of 0.91 and 0.80 V vs. RHE, respectively. Furthermore, its long-term stability and methanol tolerance were better than those of commercial Pt/C. Thus, this work presents a new strategy of using an interior bio-phosphorus source to obtain heterojunction particles featuring a phosphide-rich body and oxide-rich surface, which may provide some insights for the construction of efficient heterogeneous electrocatalysts.
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PubMed
高影响因子
ENVIRONMENTAL RESEARCH
·
2020
·
IF 5.715
Hualin Jiang,Lei Tian,Pinghua Chen,Yingchen Bai,Xueqin Li,Hongying Shu,Xubiao Luo
Co 3 O 4 @rGO were facilely prepared by template free self-assemble in this study. The morphology of Co 3 O 4 @rGO was actiniaria-like core-shell structural nanocomposites. The formation mechanism of Co 3 O 4 @rGO core-shell nanocomposite was discussed according to its significant time-dependent morphology evolution course. To evaluate the application potential of Co 3 O 4 @rGO, its adsorption performance toward highly toxic antimony ions were studied. The Co 3 O 4 @rGO nanocomposite exhibit high anti-interference ability and high adsorption ability. The maximum adsorption capacities towards Sb(III) and Sb(V) are 151.04 and 165.51 mg/g, respectively. River water samples containing antimony violating the limit were used to evaluate the practical application of Co 3 O 4 @rGO, and high performance was achieved. The EU and China limits for antimony in drinking water can be met by using mesoporous Co 3 O 4 @rGO treating the actual river water samples with original antimony concentration lower than 50 μg/L. Adsorption isotherm, adsorption kinetics, pH and co-existing ions effects were also studied in details. The results indicate that mesoporous Co 3 O 4 @rGO is an excellent adsorbent for antimony removal. Mesoporous Co 3 O 4 @rGO nanocomposite is a potential candidate for antimony removal from waste water.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Yan Wang,Xiaochuang Di,Xinming Wu,Xuanhua Li
Lightweight and high-efficiency electromagnetic (EM) wave absorption are two key factors in the research of new-type absorbers, which could be obtained by regulating the component, structure, or suitable impedance matching. In this paper, a nanoporous carbon/Co/Co 3 O 4 /carbon nanotubes (CNTs)/reduced graphene oxide (RGO) composite with polyhedral structure was prepared by high-temperature pyrolysis of Co-based zeolitic imidazolate frameworks (ZIF 67). The carbon/Co/Co 3 O 4 /CNTs/RGO composite was composed of carbon polyhedrons, in which Co and Co 3 O 4 particles were encapsulated by carbon polyhedrons and CNTs. With a filler ratio of 20 wt%, this absorber displayed the highest reflection loss (R L ) of −59.2 dB at 11.2 GHz with 2.5 mm thickness and the absorption bandwidth (R L exceeding −10 dB) of 5.7 GHz (12.3–18 GHz) with a thickness of only 2 mm. The outstanding microwave absorption performance of this material results from proper impedance matching, synergistic effect, enhanced interfacial polarizations and interior cavities. This strategy may provide guidance for the manufacture of new-type absorbers with high-efficiency characteristics.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2020
·
IF 3.807
Dandan Han,Yuan Zhao,Ye Shen,Yen Wei,Liucheng Mao,Guangjian Zeng
High electrochemical performance of supercapacitor electrodes largely rely on the heterostructure of different active component materials. Furthermore, the integration of Co 3 O 4 nanowire (internal conductive highway) to bridge the Ni-Co layered double hydroxides nanosheets (provided high specific capacity), which is favorable for fast charge transfer, as well as improved conductivity. Thus, the Co 3 O 4 @Ni-Co LDH core-shell nanowire arrays electrodes exhibit a remarkable specific capacitance (1318 F·g −1 at 0.5 A·g −1 ) and also a relatively low resistance. Due to synergistic interaction of porous NiCo-LDH nanosheets and inner Co 3 O 4 nanowire, an asymmetric supercapacitor (ASC) is assembled with Co 3 O 4 @Ni-Co LDH as the anode and active carbon as cathode. The as-fabricated ASC shows high energy density of 46.3 Wh·kg −1 and exhibit superior cyclic stability of 92% retention after 5000 cycles, suggesting this electrode is promising for efficient electrochemical capacitors.
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CARBOHYDRATE POLYMERS
·
2021
·
IF 9.381
Chen Hou,Linhui Fu,Yang Wang,Wenqiang Chen,Fang Chen,Sufeng Zhang,Jianzhi Wang
Smart nanomaterials that can simultaneously detect and eliminate contaminants in water environment are significant for health protection. To achieve such goal, Co-MOF-74 was in-situ assembled on regenerated cellulose membranes followed by calcination process, thus achieving dual-functional Co 3 O 4 /cellulose derivative membrane (Co 3 O 4 /CDM) catalyst. The Co 3 O 4 morphology was readily controlled by further recrystallization of the deposited MOF precursor. Combining the high enrichment ability of cellulose membrane and outstanding peroxidase-active of Co 3 O 4 , the fast color reaction for phenol was accomplished within 10 min by Co 3 O 4 /CDM with the assistance of H 2 O 2 and 4-aminoantipyrine (4-AAP). Moreover, the Co 3 O 4 /CDM also portrayed an excellent degradation property for phenol elimination via sulfate radical-advanced oxidation processes (SR-AOPs). The degradation efficiency of phenol reached 93% in 20 min, and the possible mineralization mechanism was proposed based on the XPS and LC-MS analysis. Thus, Co-MOF-74 derived Co 3 O 4 /CDM shows excellent properties in aiding the colorimetric detection and degradation of phenol in aqueous solutions.
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EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
·
2019
·Vol. 2019
·期 24
·2933-2939
·
IF 2.578
Xuefeng Hu,Zeshu Zhang,Yibo Zhang,Liwei Sun,Heyuan Tian,Xiangguang Yang
Graphical A Pt/Co 3 O 4 catalyst was prepared by the galvanic displacement method, which exhibited excellent catalytic activity for toluene combustion (T 90 = 150 °C at GHSV = 60 000 mL g –1 h – 1 ) and outstanding stability reflected in a continuous 100 h on-stream toluene combustion lifetime experiment without loss in catalytic activity. Catalytic combustion has become one of the most economical, feasible and effective tools for the abatement of VOCs. However, it is difficult to prepare supported Pt catalysts possessing both excellent catalytic activity and stability by traditional preparation methods, such as incipient-wetness impregnation method and nanoparticle loading method. In this work, we prepared Pt/Co 3 O 4 catalyst with high catalytic activity and stability for the catalytic combustion of toluene by galvanic displacement method. As comparing, additional reference samples were prepared using incipient-wetness impregnation method and nanoparticle loading method, respectively. All of the samples were characterized by XRD, TEM, H 2 -TPR, O 2 -TPD and XPS techniques. The catalyst prepared by galvanic displacement method exhibited the best catalytic activity with the temperature of 90 % toluene conversion about 150 °C (T 90 = 150 °C) and outstanding stability reflected in a continuous 100 h on-stream toluene combustion lifetime experiment without catalytic activity decline at the GHSV = 60 000 mL g –1 h –1 compared to which prepared by traditional methods. These results are attributed to the excellent oxygen mobility, the high surface chemisorbed oxygen species concentration and the strong interaction between Pt and support Co 3 O 4 . Therefore, our work provided a universal strategy for designing high-efficiency and stable catalyst for the abatement of VOCs at low temperature.
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ACS Catalysis
·
2015
·
IF 9.312
Zhongzhe Wei,Jing Wang,Shanjun Mao,Diefeng Su,Haiyan Jin,Yihe Wang,Fan Xu,Haoran Li,Yong Wang
The earth-abundant nanohybrids Co0/Co3O4@N-doped carbon nanotubes were fabricated via an efficient thermal condensation of d-glucosamine hydrochloride, melamine, and Co(NO3)2·6H2O. The hybrids furnish excellent catalytic activity and perfect chemoselectivity (>99%) for a wide range of substituted nitroarenes (21 examples) under relatively mild conditions. The high catalytic performance and durability is attributed to the synergistic effects between each component, the unique structure of graphene layers-coated Co0, and the electronic activation of doped nitrogen. Density functional calculations indicate that the inner Co0 core and N species on the carbon shell can significantly decrease the dissociation energies of H2, giving evidence of the ability of carbon shell in the hybrids to enable H2 activation. These results open up an avenue to design more powerful low-cost catalysts for industrial applications.
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ChemPlusChem
·
2015
·Vol. 80
·期 9
·1465-1471
·
IF 3.026
Chun-Chao Hou,Ting-Ting Li,Yong Chen,Wen-Fu Fu
Graphical Don’t look beyond the surface! A highly porous Co 3 O 4 @carbon/BiVO 4 photoanode is obtained by a facile metal–organic framework templated synthesis route. This photoanode can effectively suppress interfacial electron–hole recombination for water oxidation (see figure). Efforts to improve the overall efficiency of photoelectrochemical water splitting by promoting interfacial charge transfer and suppressing electron–hole recombination remain a challenge. Highly porous Co 3 O 4 @carbon derived from metal–organic frameworks was successfully embedded on the surface of BiVO 4 nanosheets. The Co 3 O 4 @carbon/BiVO 4 composites were fully characterised by a variety of techniques, including powder XRD, diffuse reflectance UV/Vis spectroscopy, BET surface area calculations, SEM, TEM, energy-dispersive X-ray spectroscopy, high-angle annular dark-field scanning TEM, and X-ray photoelectron spectroscopy. The construction of a heterojunction between porous Co 3 O 4 (p-Co 3 O 4 ) and BiVO 4 significantly promoted charge transfer and suppressed the recombination of holes and electrons. Consequently, the p-Co 3 O 4 @carbon/BiVO 4 photoanode demonstrated approximately tenfold higher photocurrent density relative to bare BiVO 4 and bulk Co 3 O 4 /BiVO 4 for water oxidation under the same conditions. Also, this system displayed good durability for water oxidation and could be recycled at least three times without any loss of catalytic activity.
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APPLIED SURFACE SCIENCE
·
2015
·
IF 2.711
Guangliang Chen,Xiaolei Si,Jinsong Yu,Huiyu Bai,Xianhui Zhang
This paper reports the synthesis of nanosized Ag/Co 3 O 4 composite catalysts using a silver-mirror reaction and the calibration of their catalytic activities towards methyl blue (MB) dye degradation with peroxymonosulfate (PMS) under visible light. The nanosized Ag/Co 3 O 4 composites were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy. The experimental evidence indicated that the hydrothermal synthesis approach lead to the exposure of the {1 1 2} facets of the Co 3 O 4 nanoflakes. Compared to Co 3 O 4 nanoflakes, Co 3 O 4 doped with Ag nanoparticle (average diameters of 10–15 nm) presented lower band gap energy and photoluminescent (PL) intensity. Meanwhile, the Ag/Co 3 O 4 exhibited high stability and excellent dispersion property in dye solution. Experimental data suggested that 3.06 wt% Ag nanoparticle-doped Ag/Co 3 O 4 nanocomposite catalyst possessed the highest catalytic activity towards MB degradation in aqueous solution at the tested concentration level of 15 mg/L, about 2.4 times higher than that of pure Co 3 O 4 . Complete decolorization of the 15 mg/L MB solution can be achieved by 3.06 wt% Ag-doped Ag/Co 3 O 4 nanocomposite within 20 min of visible light irradiation.
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