NEW JOURNAL OF CHEMISTRY
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2018
·Vol. 42
·期 24
·19400-19406
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IF 3.201
Wei Jin,Jianping Chen
Hydrogen (H2) is an alternative clean and sustainable energy source that could alleviate the fossil fuels crisis, and eco-friendly water electrolysis has been widely employed to produce H2. Herein, we report for the first time the facile synthesis of copper(I) oxide and cobaltosic oxide hybrid nanocomposites decorating defective carbon nanotubes (Cu2O/Co3O4/DC) using a hydrothermal method. Notably, the electrocatalysis of Cu2O/Co3O4/DC is significantly improved through an electrochemical activation process. The electrochemically activated Cu2O/Co3O4/DC (ECA-Cu2O/Co3O4/DC) presents excellent HER activity and durability with a small overpotential of 160 mV at a current density of 10 mA cm−2 and a small Tafel slope of 73 mV dec−1. This high hydrogen evolution performance is attributed to the synergistic interaction between Cu2O/Co3O4 nanoparticles and defective carbon nanotubes, providing further understanding of earth-abundant transition metal-bearing electrocatalysts in emerging energy applications.
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高影响因子
Materials Science & Engineering C-Materials for Biological Applications
·
2018
·
IF 5.08
Yunxia Zhuang,Xiaodan Zhang,Qiumeng Chen,Siqi Li,Haiyan Cao,Yuming Huang
Here, we report the synthesis, characterization, and oxidase-like activity of Co 3 O 4 /CuO hollow nanocage (HNC) nanocomposites. The Co 3 O 4 /CuO HNCs were successfully prepared by hydrothermal treatment of ZIF-67 in copper nitrate solution, followed by carbonization in air. The obtained nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The Co 3 O 4 /CuO HNCs possess enhanced oxidase-like activity compared with pure Co 3 O 4 and CuO, and they can catalytically oxidize the 3,3′,5,5′-tetramethylbenzidine (TMB) substrate in the absence of H 2 O 2 to produce an intense blue product. Reactive oxygen species (ROS) measurements indicate that 1 O 2 and O 2 − radicals are the major ROS in catalytic oxidation of TMB by dissolved oxygen in the TMB–Co 3 O 4 /CuO HNC system. We then developed a simple, sensitive, visual, and colorimetric biosensing method for dopamine (DA) based on its inhibiting effect on TMB oxidation. The proposed method allows for DA detection with a limit of detection of 0.027 μM and a dynamic range of 0.05–8 μM. This new colorimetric method was successfully used to detect DA in biological samples. The present work demonstrates a simple strategy to fabricate an efficient oxidase mimic with potential applications in bioanalysis and clinical diagnosis.
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PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2018
·
IF 6.434
Guangjun Zhai,Jinguo Wang,Zimei Chen,Shuaifeng Yang,Yong Men
Three-dimensionally ordered macroporous (3DOM) Co 3 O 4 -CeO 2 catalysts with controllable Co/Ce molar ratios synthesized by colloidal crystal template method were developed to catalyze the NO x -assisted soot oxidation for the first time, and the obtained 3DOM Co 3 O 4 -CeO 2 catalysts exhibited highly enhanced soot oxidation activity. Detailed characterizations of 3DOM Co 3 O 4 -CeO 2 catalysts revealed that the highly enhanced soot oxidation activity was originated from the synergistic promoting effect by combining the macroporous effect resulted from the unique 3DOM framework, the chemical nature associated with more Co 3+ reactive sites, the surface enrichment of Ce species and the improved redox properties. Meanwhile, the high NO x storage and oxidation capacity resulted from the integrated respective merits of Co 3 O 4 and CeO 2 also accounted for the enhanced soot oxidation activity via NO x -assisted mechanism. Furthermore, the 3DOM Co 3 O 4 -CeO 2 catalysts demonstrated strong stability because of the surface enrichment of Ce species improving the thermal stability and the robust 3DOM framework inhibiting the structural collapse, showing their potential applications under practical conditions.
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Journal of Energy Chemistry
·
2018
·
IF 3.886
Dan Li,Qiying Liu,Changhui Zhu,Haiyong Wang,Chunhua Cui,Chenguang Wang,Longlong Ma
2,5-dimethyfuran (DMF), which is produced from 5-hydroxymethyfurfural (HMF) by hydrodeoxygenation (HDO), is a high quality fuel due to the high heating value, the high octane number and the suitable boiling point. Selective hydrogenation of HMF into liquid fuel DMF has been widely researched. In this paper, Co 3 O 4 catalyst was prepared by co-precipitation and was reduced at different temperatures to form Co–CoO x catalysts. The characterization of catalysts was tested by XRD , TEM, XPS , TPR, BET and NH 3 -TPD. Co–CoO x possessed a high amount of Co metal and CoO x acidic sites, wherein Co worked as the active hydrogenation sites and CoO x acted as the acid promoter to facilitate the selective HDO of HMF to DMF. The synergistic effect of Co–CoO x is the key for HDO of HMF, obtaining 83.3% of DMF yield at 170 °C, 12 h and the reduction temperature of 400 °C. This method not only saves the catalyst cost, but also promotes the utilization of biomass energy.
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ACS Applied Materials & Interfaces
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2015
·
IF 6.723
Xiaoli Zhang,Jinbao Zhang,Kai Wang
Nanostructured Co3O4 doped with Zn2+, Ni2+, and both were directly grown on an ITO substrate by an easily available hydrothermal method. The doped Co3O4 showed a unique structural morphology evolution upon controlling the doping elements and the doping ratio of the cations. For the codoped samples, the novel rhombus-shaped Co3O4 nanosheets doped with Zn2+ and Ni2+ (concentration ratio of 1:2) exhibited the optimal electrocatalytic performance. The sample showed a current density of 165 mA cm–2 at 1.75 V, approximately 1.6 and 4 times higher than that of samples doped with Zn2+ and Ni2+ at a concentration ratio of 1:1 and 1:3. The unique architecture and its corresponding modified physical properties, such as high active-site density created by codoping, large structural porosity, and high roughness, are together responsible to its superior performance. For codoped Co3O4 nanostructures, Zn2+ facilitates the creation of Co cations in their high oxidation state as active centers, while Ni2+ contributed to the new active sites with lower activation energy. The synergistic effect of Zn2+ and Ni2+ doping can explain the improved physicochemical properties of codoped Co3O4 nanostructures.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
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2015
·Vol. 119
·期 4
·1483-1490
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IF 1.704
Wang Xiaoxia,Yu Jianhua,Dong Hongzhou,Yu Mingxun,Zhang Baoqin,Wang Wen,Dong Lifeng
In this work, metal oxide (MnO 2 , SnO 2 and Co 3 O 4 )–graphene composite materials were successfully prepared via different synthesis methods. Uniform metal oxide nanoparticles were well dispersed on graphene sheets, and transmission electron microscopy characterizations showed that the average sizes of MnO 2 , SnO 2 , and Co 3 O 4 particles were about 60, 5, and 10 nm, respectively. Reflection losses of graphene composites and pure graphene were systematically evaluated between 2 and 18 GHz, which revealed that all composites exhibited enhanced microwave absorption properties compared to pure graphene. The minimum reflection losses of MnO 2 -graphene, SnO 2 –graphene, and Co 3 O 4 –graphene composites with a thickness of 2.0 mm were −20.9, −15.28, and −7.3 dB at the frequency of 14.8, 15.94, and 9.6 GHz, respectively, whereas −4.5 dB for pure graphene. The enhanced absorption ability probably originated from the combined advantage of metal oxide particles and graphene, which proved beneficial to improve the impedance matching of permittivity and permeability. Besides, the intrinsic characteristics of MnO 2 , SnO 2 , and Co 3 O 4 nanoparticles, the interface between nanostructured metal oxides and graphene sheets, and the multi-dielectric relaxation processes are all influence factors to improve the properties of microwave absorption.
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Analytical Methods
·
2016
·Vol. 8
·期 14
·2923-2928
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IF 1.915
Xiaohua Li,Yun feng Bai,Feng Feng,Zhujun Zhang
Herein, we present a novel chemiluminescent (CL) sensor combined with an enzyme immobilization technique. We propose a versatile approach for the fabrication of CL sensors based on hydrophilic Co3O4@SiO2 mesoporous nanoparticles. The Co3O4@SiO2 mesoporous nanoparticles immobilized on the 96-well plates exhibited higher catalytic activity on the luminol–H2O2 CL reaction in an alkaline medium. Enzyme reactors were fabricated by incorporating functionalized mesoporous silica particles into calcium alginate fiber (CAF) to efficiently encapsulate the enzyme. The novel CL sensors combined with the enzyme reactors were reversible and reusable, which have been successfully exploited towards the high-throughput determination of glucose in human serum. The method was based on the generation of H2O2 from glucose in human serum by immobilized glucose oxidase (GOD). The linear range of the glucose concentration was 1.0 × 10−6 to 8.0 × 10−5 M and the detection limit was 1.2 × 10−7 M.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2017
·
IF 9.446
Chunmei Cao,Lingli Xing,Yuexi Yang,Ye Tian,Tong Ding,Jing Zhang,Tiandou Hu,Lirong Zheng,Xingang Li
Herein, we report the high catalytic activity of the potassium-promoted Co 3 O 4 nanowires supported on the monolithic three-dimensional macroporous (3-DM) nickel foam substrate (xKCo-NW) for soot combustion. The 3-DM structure of Ni foam and the space among these nanowires can extremely improve the contact efficiency between soot and catalysts. Loading of potassium provides the new active sites for soot oxidation , improves catalyst-soot contact as a molten salt and increases the number of the surface adsorbed oxygen species. The 5KCo-NW catalyst loaded with 5% potassium shows the highest catalytic performance, as well as a high water resistance. There are two types of potassium species in the catalysts, most potassium species is in the form of separate phases, and few interacts with cobalt oxide. The interaction between potassium species and cobalt oxide stabilizes a part of potassium species, and the stabilized potassium species can promote the catalytic activity for the consecutive soot combustion cycle. Moreover, our results show that the chemisorbed NO x species on the 5KCo-NW catalyst are more active than the gaseous NO 2 for soot oxidation. In the presence of O 2 , soot combustion is accelerated to react with the chemisorbed NO x species; whereas the formed nitrate/nitrite species are catalytically inert.
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SENSORS AND ACTUATORS B-CHEMICAL
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2016
·
IF 4.758
Longjiang Ding,Minggang Zhao,Sisi Fan,Ye Ma,Jingjing Liang,Xingtao Wang,Yawen Song,Shougang Chen
A new Co 3 O 4 electrode material with self-supporting urchin-like hollow microspheres structure was fabricated via a self-assembly method. Incorporating the adsorption and entrapment, the high porosity and large surface area were favorable for the highly effective immobilization of glucose oxidases . Multiple responses, consisting of enzymatic and material catalysis, were subsequently employed and achieved on the microsphere surface. As the radially oriented nanowires array provided a vast number of catalytic active sites, which lowered the energy barrier of glucose redox and acted as a media to boost the electron transfer, the detection potential was largely decreased. Furthermore, numerous electron transport paths in a short distance were formed among the interconnected bridge-like nanowires, resulting in improved electron transfer efficiency. The prepared glucose biosensor exhibited extra high sensitivity (102.77 μA mM −1 cm −2 ), fast response (3 s) and outstanding selectivity and stability at a lower applied potential (0.35 V).
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CRYSTENGCOMM
·
2016
·Vol. 18
·期 42
·8253-8261
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IF 3.849
Kun Ding,Xiao Zhang,Ping Yang,Xin Cheng
The controlled synthesis of multifarious nanostructures is valuable for understanding the properties associated with the surface structure and for exploring potential applications. Herein, various morphological Co3O4 precursors were synthesized hydrothermally for fabricating mesoporous Co3O4 nanostructures. Importantly, the morphology, size, and crystalline phase of precursors were independently tuned by controlling the components in solution (e.g. anions, cations, and hydrolysis agents). The microstructure of Co3O4 precursors has obviously changed from porous hexagons to nanoneedles by changing the anions in solution. After calcination, as-prepared precursors were converted into mesoporous Co3O4 nanostructures, and their morphology and size were well preserved. The effect of experimental conditions on the growth of Co3O4 precursors was explored, and the corresponding growth mechanism was proposed. Moreover, the electrochemical properties of Co3O4 with different morphologies were tested. The results showed that the 3D hierarchical flower-like Co3O4 assembled by hexagonal nanosheets exhibited higher specific capacitance (327.3 F g−1 at 0.5 A g−1) with excellent retention (96.07% at 5 A g−1) after 10 000 cycles. It is believed that this anion-assisted synthetic approach can be extended to the preparation of other transition metal oxides.
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Catalysis Science & Technology
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2016
·Vol. 6
·期 19
·7273-7279
·
IF 5.287
Guozhu Chen,Qihui Xu,Yong Wang,Guolong Song,Cuncheng Li,Wei Zhao,Weiliu Fan
It is still an important issue to develop a facile, environmentally friendly way to synthesize bimetal oxide materials. In this paper, Co3O4–CeO2 core–shell catalysts were prepared by an interfacial reaction, where Co(CO3)0.35Cl0.2(OH)1.1 nanorods were dispersed in Ce3+ aqueous solution for 2 days, followed by a calcination step. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Based on the characterization and comparative experimental results, we proposed that the OH− ions slowly dissociated from the Co(CO3)0.35Cl0.2(OH)1.1 precursor combined with Ce3+ to develop into Ce(OH)3 nanoparticles because of its smaller solubility product constant than that of the Co precursor or Co(OH)2. Neither an additional precipitation agent nor stabilizing molecules were employed during the whole preparation. Raman spectroscopy and H2-temperature programmed reduction (H2-TPR) analysis revealed that there is a synergistic effect between Co3O4 and CeO2 in the as-prepared Co3O4–CeO2 core–shell catalysts, which is responsible for their enhanced catalytic activity toward CO oxidation in comparison to pure Co3O4 and CeO2.
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ELECTROCHIMICA ACTA
·
2024
·
IF 5.5
Minglan Dai,Ting Zhang,Juan Huang,Xiaomin Lang,Qing Li,Jian Zou,Chunmei Li,Jianfeng Tang,Hua Lin
Building p-p heterojunctions with Fermi level difference, due to the motion of energy levels, band bending, and internal electric field generation, can effectively improve the electronic structure of the interface, enrich the active sites of heterojunctions, and promote the adsorption of reaction intermediates, which is an effective approach to constructing high-performance electrocatalysts . In this study, a Co 3 O 4 /MoS 2 p-p heterojunction catalyst with nano-particle/nano-flower structure was designed, inducing charge transfer from Co 3 O 4 to MoS 2 , thereby increasing the negative charge of MoS 2 , improving *H adsorption through electrostatic interaction , enhancing electrocatalytic kinetics, and reducing reaction overpotential. The catalytic performance of MoS 2 for hydrogen evolution reaction was effectively enhanced. In 1 M KOH solution, the current density was 10 mA cm −2 , and the overpotential was 156 mV, with good stability after 40 h of operation. This work provides a new direction for the design of p-p heterojunction electrocatalysts and offers more choices for promoting the development of high-performance non-noble metal catalysts.
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