ACS Applied Bio Materials
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2021
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IF 0
Jianzhong Huo,Jinyu Hao,Jianshuai Mu,Yan Wang
Nanomaterial-based mimetic enzymes, called nanozymes, received more and more attention in recent decades; however, their lack of biocompatibility limited the biomedical applications, which could be solved by surface modification. In this work, the Co3O4 nanoplates were modified by different functional groups, including the amino group, carboxyl group, hydroxyl group, and sulfhydryl group (NH2-Co3O4, COOH-Co3O4, OH-Co3O4, and SH-Co3O4). And the modified Co3O4 nanoplates were characterized by XRD, SEM, TEM, XPS, FTIR, TG, and the Zeta potential, verifying the successful modification of different functional groups. Their mimetic peroxidase properties and kinetics process were further studied and showed that the order of their catalytic activities was as follows: NH2-Co3O4 > SH-Co3O4 > COOH-Co3O4 > pure Co3O4 > OH-Co3O4, and the catalysis of modified Co3O4 nanozymes all followed Michaelis–Menten kinetics. The results indicated that the different functional groups changed their electron transfer ability, and further affected their catalytic activity. H2O2 detection was selected as an application model system to evaluate the modified Co3O4 nanozymes. Compared with other Co3O4 nanozymes, a wider linear range from 0.01 to 40 mmol L–1 and a lower detection limit of 1.5 μmol L–1 was constructed with NH2–Co3O4 nanozymes. The results suggested that surface modification by functional groups was a robust strategy to improve the application of Co3O4 nanozymes. The enhanced catalytic activity and good biocompatibility of modified Co3O4 nanozymes provided valuable materials for the relative application, such as medical detection and antioxidation.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2020
·
IF 16.683
Huiyan Zeng,M'hamed Oubla,Xuepeng Zhong,Nicolas Alonso-Vante,Fei Du,Yu Xie,Yunhui Huang,Jiwei Ma
Mesoporous Co 3 O 3.87 ◻ 0.13 (◻ represents oxygen vacancies) and Co 3 O 3.87 F 0.13 electrocatalysts, integrating advantages of oxygen vacancies and fluorine anion, were deployed. Co 3 O 3.87 ◻ 0.13 and Co 3 O 3.87 F 0.13 showed enhanced oxygen evolution reaction (OER) with overpotentials of 440 mV and 430 mV at 10 mA cm −2 , Tafel slopes of 56 mV dec -1 and 56 mV dec -1 , turnover frequency (TOF η= 400 mV ) of 0.023 s -1 and 0.042 s -1 respectively, as compared to Co 3 O 4 (520 mV, 64 mV dec -1 , 0.0005 s -1 ) in the alkaline medium. Physicochemical characterizations showed that oxygen vacancies and the substituted fluorine modified the electronic structure, leading to the enhanced activity for OER process, consistent with the theoretical calculation. This approach provides ideas for rational design of new defective fluorinated oxide, with the feasible extension of such an approach to a wide variety of transition metal oxides.
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2020
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IF 2.627
Xiang Li,Bo Yang,Yaqin Wu,Saisai Lin,Lin Zhang
Homogeneous NaBH 4 -reduced Co 3 O 4 thin film electrodes with enhanced oxygen evolution electrocatalysis were obtained via a controlled-synthesis route. Firstly CoO x colloids were synthesized via ethylene glycol solvothermal method and cast on conductive glass substrates. The oxygen evolution reaction (OER) electrocatalysis of these as-prepared Co 3 O 4 thin films were then significantly enhanced via a simple surface reduction by NaBH 4 solution. The OER catalytic performance of the NaBH 4 -reduced thin films was strongly dependent on the NaBH 4 concentration. The use of NaBH 4 -reduced thin film electrodes for OER in alkaline solution supported higher current density and consequently negative shifts of the onset potential compared to that of the pristine. The optimal B 12.5, 20 -Co 3 O 4 thin films exhibited excellent OER catalytic performances: At the current density of 10 mA·cm −2 , a low overpotential of 365 mV and a small Tafel slope of 59.0 mV·dec −1 were observed. In addition, these B 12.5, 20 -Co 3 O 4 thin film electrodes possessed good stability that can well recover its OER performance in a 24-h chronoamperometric stability test.
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APPLIED SURFACE SCIENCE
·
2020
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IF 6.182
Weichun Yang,Xingyao Li,Zhi Jiang,Chaofang Li,Jie Zhao,Haiying Wang,Qi Liao
Co 3 O 4 crystals with different shapes and surface structures were successfully synthesized. The shapes obtained included flower-like nanoplates (FN), nanocubes (NC), nanosheets (NS) and flake-stacked microsphere (FM). The shapes and surface structures of the Co 3 O 4 catalysts significantly affected their catalytic activity. Among the as-synthesized Co 3 O 4 catalysts, the NC sample displayed the highest catalytic activity in persulfate (PS) activation, achieving almost complete removal of 30 mg L −1 orange G (OG) within 10 min at the reaction conditions of 0.5 g L −1 catalyst and 8.0 mM PS. The excellent catalytic performance of NC sample could be ascribed to dominant exposed crystal plane and abundant surface hydroxyl groups. The electron paramagnetic resonance (EPR) and radical quenching tests demonstrated that reactive oxygen species (ROS) including sulfate radical ( · SO 4 − ), hydroxyl radical ( · OH), superoxide radical ( · O 2 – ) and singlet oxygen ( 1 O 2 ) were generated in the NC/PS system, while 1 O 2 was dominantly attributed to the OG degradation. The exposed plane of (1 1 1) may be responsible for the generation of 1 O 2 . The study dedicates a novel mechanism of PS heterogeneous activation by Co 3 O 4 crystals and provides an ideal catalyst for efficient removal of organic pollutants in wastewater.
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Russian Journal of Physical Chemistry A
·
2019
·Vol. 93
·期 10
·2067-2071
·
IF 0.581
Jianfeng Dai,Zhu Xiaojun,Liu Jifei,Wang Qing,Li Weixue,Qi Yufeng
Abstract Nanostructuring is a promising approach to the problems of low diffusion coefficient of transition metal oxides anodes. Co 3 O 4 nanofibers electrode materials were successfully synthesized by electrospinning followed by controlled pyrolysis. Electrode materials based on Co 3 O 4 nanofibers applied as anode for lithium-ion batteries (LIBs) show high discharge-charge specific capacity of 595 and 527 mA h g –1 at 0.5C, respectively. Further electrochemical investigation reveals that Co 3 O 4 nanofibers exhibiting high specific capacity (300 mA h g −1 at 0.5C after 200 cycles), the capacity fading is only 11.8% after 200 cycles. Further electrochemical studies reveal that these excellent electrochemical properties should be attribute to the ordered ions diffusion pathway originated from the one-dimensional nanostructure and continuous fibrous network structure. These results revealed that the Co 3 O 4 nanofibers are promising anode materials for LIBs.
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2023
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IF 3.8
Huijun Shang,Hengli Li,Weijun Li,Feng Pan,Zhan Du
ABSTRACT In order to avoid the formation of η phase (W 6 Co 6 C or W 3 Co 3 C) that adversely affects the sintering process and its products in the preparation process of ultra-fine WC-Co powder, a technical route of pre-reduction of WO 3 –Co 3 O 4 to WO 2 –Co and then deep reduction carbonization to WC-Co powder has been proposed. This study mainly investigates the influence of gas partial pressure on the pre-reduction process of WO 3 –Co 3 O 4 under a mixed atmosphere of H 2 –C 2 H 4 –Ar at 600 °C and establishes the kinetic equations of pre-reduction and carbon evolution. The results indicate that increasing the partial pressure of hydrogen is conducive to the rapid and complete conversion of WO 3 to WO 2 . High carbon content can be generated by the deposition of C 2 H 4 , and it hinders the diffusion of the reducing gas; WO 3 still cannot be completely reduced to WO 2 as the partial pressure of C 2 H 4 increases to 60%. For the carbon evolution of C 2 H 4 , the carbon amount is positively related to the H 2 partial pressure, but it shows the highest amount and evolution rate when the ethylene partial pressure is 20%. Based on the reduction rate curves of WO 3 and carbon evolution rate curves of C 2 H 4 , the rate equations of pre-reduction and carbon evolution of WO 3 –Co 3 O 4 system at 600 °C are established. The pre-reduction reaction belongs to the first-order reaction, and its equation is expressed as follows: r = − d w WO 3 d t = 9 ± 0.15 × 1 0 − 2 P H 2 0.44 P C 2 H 4 0.57 The carbon deposition rate equation of C 2 H 4 can be expressed as follows: r ' = d c C d t = r f − r b ≅ 7.35 × 1 0 − 2 × P C 2 H 4 0.31
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MOLECULES
·
2023
·Vol. 28
·期 21
·7396
·
IF 4.6
Huihui Chen,Mei Yang,Yuan Liu,Jun Yue,Guangwen Chen
The design and fabrication of nanomaterials with controllable morphology and size is of critical importance to achieve excellent catalytic performance in heterogeneous catalysis. In this work, cobalt oxide (Co3O4) nanostructures with different morphologies (nanoplates, microflowers, nanorods and nanocubes) were successfully constructed in order to establish the morphology–property–performance relationship of the catalysts. The morphology and structure of the nanostructured Co3O4were characterized by various techniques, and the catalytic performance of the as-prepared nanostructures was studied by monitoring the reduction of p-nitrophenol to p-aminophenol in the presence of excess NaBH4. The catalytic performance was found to be strongly dependent on their morphologies. The experimental results show that the pseudo-first-order reaction rate constants for Co3O4nanostructures with various shapes are, respectively, 1.49 min−1(nanoplates), 1.40 min−1(microflowers), 0.78 min−1(nanorods) and 0.23 min−1(nanocubes). The Co3O4nanoplates exhibited the highest catalytic activity among the four nanostructures, due to their largest specific surface area, relatively high total pore volume, best redox properties and abundance of defect sites. The established correlation between morphology, property and catalytic performance in this work will offer valuable insight into the design and application of nanostructured Co3O4as a potential non-noble metal catalyst for p-nitrophenol reduction.
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INORGANIC CHEMISTRY COMMUNICATIONS
·
2023
·
IF 3.8
Mei Dong,Guomeng Zhang,Guiping Ma
Advanced oxidation processes based on sulfate radicals (SR-AOPs) are gaining more and more attention for their efficient treatment of refractory organic contaminants, and the rational design of catalyst is the key for the effectiveness of the method. In this paper, a Co 3 O 4 @ZIF-67 core–shell heterogeneous catalyst for activation of peroxymonosulfate (PMS) to degrade methylene blue (MB), a refractory dye, was prepared successfully. Under conditions of 20 mg/L catalyst, PMS 100 mg/L and and 25 °C temperature, nearly 100 % degradation of MB (10 mg/L) occured within 5 min, indicating that the core–shell catalyst possessed excellent catalytic performance. Furthermore, this core–shell structure provided stability for the nanoparticles (NPs) as less leaching of Co ions was observed. To identify the reactive species involved, quenching tests and electron paramagnetic resonance (EPR) were carried out. The results found that radical species including •OH, SO 4 ∙ - and non-radical ( 1 O 2 ) contributed to the degradation of MB and 1 O 2 was the leading one. Some important parameters, such as PMS and Co 3 O 4 @ZIF-67 doses, were explored and evaluated. Moreover, cycling study was conducted and Co 3 O 4 @ZIF-67 showed good recyclability. This work puts forward an idea of developing high-performance catalysts with structure more stable.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2023
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IF 4.5
Yanli Zhang,Jiuqing Xiong,Shihai Yan,Bingping Liu
Electrochemical reduction of nitrate to NH 3 is a very promising alternative reaction to the Haber-Bosch process, and it is necessary to develop the efficient electrocatalysts. In this study, a particle-support mode Co 3 O 4 catalyst was synthesized with ZIF-67 as the precursor, and then dispersed on MoS 2 nanoflowers by hydrothermal method. The Co 3 O 4 is anchored to MoS 2 by forming Co-S coordination bond. Furthermore, the particle-supported Co 3 O 4 exhibits better performance than Co 3 O 4 alone, as is manifested by higher Faradaic efficiencies and NH 3 yield rate at − 0.64 V (52.69% vs 32.03%; 4539.61 μg h −1 mg −1 cat vs 2048.63 μg h −1 mg −1 cat ), lower energy barriers (0.96 eV vs 1.19 eV), and better electronic conductivity (Bandwidth: 0.581 eV vs 0.613 eV). In addition, this research provides an effective solution to solve the aggregation problem of metal oxide nanoparticles.
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Materials
·
2023
·Vol. 16
·期 10
·3879
·
IF 3.4
Yelin Dai,Ziyi Feng,Kang Zhong,Jianfeng Tian,Guanyu Wu,Qing Liu,Zhaolong Wang,Yingjie Hua,Jinyuan Liu,Hui Xu,Xingwang Zhu
Water pollution is a significant social issue that endangers human health. The technology for the photocatalytic degradation of organic pollutants in water can directly utilize solar energy and has a promising future. A novel Co3O4/g-C3N4type-II heterojunction material was prepared by hydrothermal and calcination strategies and used for the economical photocatalytic degradation of rhodamine B (RhB) in water. Benefitting the development of type-II heterojunction structure, the separation and transfer of photogenerated electrons and holes in 5% Co3O4/g-C3N4photocatalyst was accelerated, leading to a degradation rate 5.8 times higher than that of pure g-C3N4. The radical capturing experiments and ESR spectra indicated that the main active species are •O2−and h+. This work will provide possible routes for exploring catalysts with potential for photocatalytic applications.Keywords:photocatalyst;type-II heterojunction;carrier separation;photodegradation
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International Journal of Electrochemical Science
·
2023
·
IF 1.5
Ruyi Zou,Lin Zhu,Guiling Luo,Yanyan Niu,Hui Xie,Ruixia Dong,Hui Cheng,Wei Sun,Laijun Zhang
Arginine-assisted thermal decomposition technique was used to prepare nanosized Co 3 O 4 (A-Co 3 O 4 ) with its supercapacitive performances checked. A-Co 3 O 4 was characterized by different techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. Brunauer-Emmett-Teller analysis revealed that A-Co 3 O 4 had a larger specific surface area than Co 3 O 4 prepared by conventional calcination without arginine (F-Co 3 O 4 ). Electrochemical performances of A-Co 3 O 4 based electrode were better than that of the F-Co 3 O 4 based electrode. Cyclic voltammetric results showed the specific capacitances of A-Co 3 O 4 and F-Co 3 O 4 were found to be 259.2 and 122.2 F/g at a scan rate of 0.01 V/s. Long-term galvanostatic charge-discharge cycling tests indicated the specific capacitance for A-Co 3 O 4 and F-Co 3 O 4 were 128.6 F/g and 106.4 F/g with 104.7% and 103.3% capacitance retention after 1000 cycles at a current density of 5.0 A/g. Electrochemical impedance spectra analysis showed the charge transfer resistance (Rct) of A-Co 3 O 4 was 7.56 Ω and that of F-Co 3 O 4 was 15.56 Ω. All the results indicated the A-Co 3 O 4 exhibited superiority originated from large surface area with porous structure.
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JOURNAL OF HAZARDOUS MATERIALS
·
2023
·
IF 13.6
Baolin Chang,Tiannan Cao,Zhizhang Shen,Yipu Zhang,Zhenyu Wang,Ji Li,Jinze Lyu
Obtaining high removal rate of chlorinated volatile organic compounds (CVOCs) and CO 2 selectivity with a low ratio of O 3 /CVOC and energy consumption is challenging. Dodecylamine was used in this study to create active sites on Co 3 O 4 for photo-ozone catalytic mineralization of dichloromethane (DCM). Amine-Co 3 O 4 -450 is a dodecylamine-modified sample with high density of Co 3+ , Co 2+ , and hydroxyl due to its nanosheet structure and exposed (112) facets. The optimized surface significantly enhanced the cleavage of the C–Cl bond at low temperatures. Photocatalysis primarily participated in the oxidation of intermediates following DCM dichlorination and significantly improved CO 2 selectivity. The respective DCM removal rate and mineralization efficiency of Amine-Co 3 O 4 -450 with an O 3 /DCM molar ratio of 1.27 and one-sun irradiation were 14.9 and 15.0 times higher than the sum of those in the presence of light irradiation or O 3 alone. This finding indicated that a strong synergistic effect exists between O 3 and light.
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