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487 results on '"Zhu, Qingjun"'

153. Engineering Interface with One-Dimensional Co3O4 Nanostructure in Catalytic Membrane Electrode: Toward an Advanced Electrocatalyst for Alcohol Oxidation

Author

Yin, Zhen, primary, Zheng, Yumei, additional, Wang, Hong, additional, Li, Jianxin, additional, Zhu, Qingjun, additional, Wang, Ye, additional, Ma, Na, additional, Hu, Gang, additional, He, Benqiao, additional, Knop-Gericke, Axel, additional, Schlögl, Robert, additional, and Ma, Ding, additional

Published
2017
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155. An Optimized Method for Bonner Sphere Spectrometer Design and Validation by Measuring 252Cf Spectra

Author

Zhu, Qingjun, Meng, Xianfang, Chen, Wuhui, Liu, Songlin, and Huang, Kai

Abstract

AbstractA methodology for designing a Bonner sphere spectrometer was proposed based on the singular value decomposition (SVD) and information entropy theory. First, features of Bonner spheres were classified based on SVD, and then, the rationality of the selected spheres was analyzed. Second, the information entropy is used as the quantitative evaluation standard; combined with the unfolding method, the contribution of each Bonner sphere on the information entropy of the unfolded spectra was quantitatively analyzed. The spheres that have high influence on the information entropy of solution spectra can be identified, and then, the information entropy variation of the solution spectra can be suppressed by reducing the count fluctuation of these spheres. According to the proposed method, an optimized spectrometer was developed and applied to measuring 252Cf spectra.

Published
2021
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164. Correction: Effect of graphene oxide on anticorrosion performance of polyelectrolyte multilayer for 2A12 aluminum alloy substrates

Author

Xiaofan Zhai, Zhu Qingjun, Baorong Hou, Xiaolin Sun, Binbin Zhang, Liu Shuan, Jin Zuquan, and Zhao Xia

Subjects
Materials science, Graphene, General Chemical Engineering, Alloy, Oxide, chemistry.chemical_element, 02 engineering and technology, General Chemistry, engineering.material, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, GeneralLiterature_MISCELLANEOUS, Polyelectrolyte, 0104 chemical sciences, law.invention, chemistry.chemical_compound, chemistry, Chemical engineering, law, Aluminium, Hardware_INTEGRATEDCIRCUITS, engineering, 0210 nano-technology
Abstract

Correction for ‘Effect of graphene oxide on anticorrosion performance of polyelectrolyte multilayer for 2A12 aluminum alloy substrates’ by Xia Zhao et al., RSC Adv., 2017, 7, 33764–33774.

Published
2017
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166. Review and Perspectives of the In SituModification Strategy for Bifunctional Electrodes in a Vanadium Redox Flow Battery

Author

Xiao, Yanna, Yuan, Caiyue, Fan, Weijia, Wang, Yinhui, Li, Yuan, Feng, Zemin, Qi, Shaotian, Jiang, Yingqiao, Li, Yuehua, Zhu, Qingjun, Dai, Lei, and He, Zhangxing

Abstract

A vanadium redox flow battery (VRFB) represents the most commercially advanced and mature technology among redox flow batteries presently available. However, the catalytic activity of the original electrode material significantly hinders the energy efficiency of the vanadium ion redox reactions. Therefore, improving the electrodes is imperative to enhance the performance of the battery. VRFB commercialization is facilitated by the utilization of bifunctional electrodes acquired through in situmodification techniques. This approach enhances the performance of both the positive and negative electrodes, thereby increasing the efficiency of the battery. This study provides a summary of research concerning bifunctional electrodes acquired through in situmodification, including acid treatment, electrochemical treatment, heat treatment, and some novel methods. Furthermore, the application and challenges associated with bifunctional electrodes in VRFB are also outlined. This review concludes with a perspective on the future trajectory of VRFB development, elucidating the direction of its commercial advancement.

Published
2024
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167. Engineering Interface with One-Dimensional Co3O4Nanostructure in Catalytic Membrane Electrode: Toward an Advanced Electrocatalyst for Alcohol Oxidation

Author

Yin, Zhen, Zheng, Yumei, Wang, Hong, Li, Jianxin, Zhu, Qingjun, Wang, Ye, Ma, Na, Hu, Gang, He, Benqiao, Knop-Gericke, Axel, Schlögl, Robert, and Ma, Ding

Abstract

Electrochemical oxidation has attracted vast interest as a promising alternative to traditional chemical processes in fine chemical synthesis owing to its fast and sustainable features. An electrocatalytic membrane reactor (ECMR) with a three-dimensional (3D) electrode has been successfully designed for the selective oxidation of alcohols with high current efficiency to the corresponding acids or ketones. The anode electrode was fabricated by the in situloading of one-dimensional (1D) Co3O4nanowires (NWs) on the conductive porous Ti membrane (Co3O4NWs/Ti) viathe combination of a facile hydrothermal synthesis and subsequent thermal treatment. The electrocatalytic oxidation (ECO) results of alcohols exhibited superior catalytic performance with a higher current efficiency on the Co3O4NWs/Ti membrane compared with those of Co3O4nanoparticles on the Ti membrane (Co3O4NPs/Ti). Even under low reaction temperatures such as 0 °C, it still displayed a very high ECO activity for alcohol oxidation in the ECMR. For example, >99% conversion and 92% selectivity toward benzoic acid were obtained for the benzyl alcohol electrooxidation. The electrode is particularly effective for the cyclohexanol oxidation, and a selectivity of >99% to cyclohexanone was achieved at 0 °C, higher than most reported noble-metal catalysts under the aerobic reaction conditions. The extraordinary electrocatalytic performance of the 3D Co3O4NWs/Ti membrane electrode demonstrates the significant influence of morphology effect and engineering interfaces in membrane electrodes on the electrocatalytic activity and charge transfer process of nanocatalysts. Our results propose that similar membrane electrodes serve as versatile platforms for the applications of 1D nanomaterials, porous electrodes, and ECMRs.

Published
2024
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170. Factors Affecting Stray Currents Corrosion of Buried Pipeline

Author

Zhu Qingjun and Hou Baorong

Abstract

Pipelines are becoming more and more familiar in modern society. Although they are effective seemingly, most of these pipelines are influenced by various corrosions. Stray current corrosion is the most severe form of corrosion because the metallic structure is forced to become an anode and the amount of current can be translated directly into metal loss. One ampere of DC current discharge from a pipeline/well casing for one year may consume 10kg of steel. Stray current is a key role in producing pipeline corrosion. However, it is very complicated to control stray current corrosion because many factors can affect the current flowing between the source and pipelines. Pipeline design and maintenance require factors influencing stray current corrosion. In this paper, soil resistivity, coating worn rate, buried depth and horizon distance have been studied. The specific factor influencing stray currents corrosion are studied by the method of keeping other elements fixed. The results show stray current can be influenced by soil resistivity, coating worn rate and buried depth in different degree. It is favorable to control stray current corrosion by increase soil resistivity, buried depth and horizon distance or decrease coating worn rate. There are boundary values in controlling stray current corrosion by increasing soil resistivity, buried depth and horizon distance. In this laboratory study, the boundary horizon distance is 200mm.

Published
2015
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182. Single-Step Formation of Metal Oxide Nanostructures Wrapped in Mesoporous Silica and Silica–Niobia Catalysts for the Condensation of Furfural with Acetone.

Author

Skrodczky, Kai, Antunes, Margarida M., Zhu, Qingjun, Valente, Anabela A., Pinna, Nicola, and Russo, Patrícia A.

Subjects
*MESOPOROUS silica, *METALLIC oxides, *FURFURAL, *CATALYSTS, *ALDOL condensation, *METAL catalysts
Abstract

The integration of metal oxide nanomaterials with mesoporous silica is a promising approach to exploiting the advantages of both types of materials. Traditional synthesis methods typically require multiple steps. This work instead presents a fast, one-step, template-free method for the synthesis of metal oxides homogeneously dispersed within mesoporous silica, including oxides of W, Ti, Nb, Ta, Sn, and Mo. These composites have tunable metal oxide contents, large surface areas, and wide mesopores. The combination of Nb2O5 nanoparticles (NPs) with SiO2 results in an increased surface area and a larger number of acid sites compared to pure Nb2O5 NPs. The surface texture and acidity of the silica–niobia composites can be tuned by adjusting the Nb/Si molar ratio. Moreover, the silica provides protection to the niobia NPs, preventing sintering during thermal treatment at 400 °C. The silica–niobia materials exhibit superior performance as catalysts in the aldol condensation of furfural (Fur) with acetone compared to pure niobia, leading to an up to 62% in product yield. Additionally, these catalysts show remarkable stability, retaining their performance over multiple runs. This work demonstrates the potential of the proposed synthesis approach for preparing more sustainable, high-performance, durable, and stable nanoscale metal oxide-based catalysts with a tunable composition, surface area, and active site density. [ABSTRACT FROM AUTHOR]

Published
2023
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190. Flake-like ZnAl alloy powder modified waterborne epoxy coatings with enhanced corrosion resistance.

Author

Zhang, Jiajia, Zhu, Qingjun, Wang, Zhiyi, Wang, Xin, and Yan, Jiayang

Subjects
*METAL powders, *EPOXY coatings, *ALLOY powders, *CORROSION resistance, *SALT spray testing, *STEEL corrosion
Abstract

Zinc-rich epoxy coatings (ZRECs) have been widely used to protect steel against corrosion because of their excellent corrosion resistance. However, the ZRECs preparation usually used a large amount of Zn powders and organic solvents, which not only wasted resources but also produced a great quantity of volatile organic compounds (VOC). Therefore, it was necessary to develop a method which can prepare epoxy coatings with low Zn content, great corrosion resistance and green environmental protection. In this paper, three different flake metal powders (Zn, ZnAl alloy and ZnAlMg alloy) were used to replace spherical Zn powders to develop environmentally friendly coatings with low pigment content. The coatings were evaluated by salt spray test and electrochemical test. The results show that the use of flake metal powders instead of spherical zinc pigments can enhance the electrical connection between metal particles, prolong the path of corrosive medium infiltration into the coatings, enhance the physical shielding effect of the coatings, and reduce the pigment content by one third. Among them, the ZnAl coatings displayed the best anti-corrosion performance resisting salt fog corrosion for 28 days. In addition, the experimental results show that the self-healing ability of the coatings also plays an important role in the immersion middle and late stages. In short, the waterborne epoxy ZnAl coatings are suitable for large-scale application in harsh environments. • An environmentally-friendly, low-cost and low pigment concentration waterborne epoxy coating is developed. • Using flake-like alloy powders in coatings can reduce the consumption of pigments while maintaining good corrosion resistance. • Flake-like alloy powders exhibit "maze effect" and extend corrosion path effectively. • Corrosion resistance of Zn coating and ZnAl coating are better than ZnAlMg coating due to self-healing ability. [ABSTRACT FROM AUTHOR]

Published
2023
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