Catalysts
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2023
·Vol. 13
·期 3
·490
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IF 3.9
Wenrui Zhang,Meilu Hao,Yonghui Wang,Pengfei Sun,Dongjuan Zeng,Xinya Wang,Peng Liang
Layered δ-MnO2catalysts were prepared using the one-step redox method in precursor solutions with five different pH values (pH = 7, 9, 11, 13, and 14). The effects of pH on the physical properties and catalytic activity of the catalyst were investigated through XRD, SEM, TEM, BET, XPS, H2-TPR, and HCHO degradation tests at room temperature. The results showed that the layer spacing, manganese vacancy content, Mn4+/Mn3+ratio, and surface-reactive oxygen species content of MnO2increased with the increase in pH value in the alkaline range. When the catalyst was prepared at pH = 13, the above characteristics of the catalyst reached the optimal value which contributed to the high catalytic activity. Combined with the related characterization results, it was proved that changing the pH can affect the degree of oxidation in the catalyst synthesis process, increase the number of active oxygen and the oxygen mobility of the catalyst, and effectively improve the catalytic activity of the manganese dioxide catalyst for HCHO. This work represents a giant step toward the preparation of an effective catalyst for practical applications of HCHO removal at room temperature at a low concentration and high velocity.Keywords:δ-MnO2;pH;formaldehyde;manganese vacancy;surface-reactive oxygen species
研究领域:
催化
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环境科学
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材料科学
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Rui Huang,Shaohua Luo,Qi Sun,Xin Yan,Haoran Zhang,Lixiong Qian,Xin Liu,Xingzhong Cao,Peng Zhang,Shengxue Yan
Fe/Mn-based cathode is considered a viable choice for sodium-ion batteries (SIBs) because of its affordability and high theoretical capacity. Nonetheless, bad actually comprehensive performance still impede its commercial application. In this work, based on the systematic study of P2-Na 2/3 Fe 1/2 Mn 1/2 O 2 cathode materials with fewer Mn vacancies (NFM-Q), we realized a superior rate, cycling performance, air stability and more importantly unraveled the operation mechanism. Specifically, dual function of fewer Mn vacancies were explicitly clarified, which included the effect of shrinking sodium layers and the sodium-ion diffusion promoting effect, as confirmed by combining XRD, XANES, XAFS, EIS and GITT. So Mn vacancy engineering had the potential to break the contradiction between “sodium limiting” based on air-stabilization mechanism and “sodium promoting” based on kinetics. This has rarely been found before. And a series of characterizations strongly declared rapidly cooling rate could effectively regulated the creation of Mn vacancies. As a result, NFM-Q cathode not only delivered outstanding discharge capacity (192.7 mAh/g), cycling stability (123.8 mAh/g, 65 %, after 50 cycles) and energy density (574.0 Wh Kg −1 ), but also possessed splendid air stability (185.8 mA h/g, 61.8 % after 50 cycles and immersion). Moreover, ex-situ XRD and XAS further expounded structural evolution and charge compensation mechanism of NFM-Q cathode, confirming its superior performance. This work might offer fresh understanding about the roles of Mn vacancy engineering, which could open up new possibilities on the material design and the property improvement of Fe/Mn-based cathodes.
研究领域:
材料科学
·
电化学
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产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2025
·
IF 21.1
Wei Liao,Minghu Zhang,Jiangping Liu,Weikun Wang,Jichang Lu,Jin Zhang,Yumin Zhang,Wenjie Zhu,Yongming Luo
Previous studies have primarily focused on the role of single defects, particularly oxygen vacancies, in the catalytic oxidation of volatile organic compounds (VOCs). However, the mechanisms by which coexisting defects influence catalytic activity remain unclear. In this work, dual manganese and oxygen vacancies were introduced in Mn 3 O 4 via solvothermal synthesis and low-temperature H 2 treatment, and a comprehensive analysis of catalysts with varying defect configurations was performed. The introduction of dual vacancies in V Mn -100-1 resulted in a reduced MnO 4 /MnO 6 ratio, leading to significant structural modifications. These changes enhanced the redox properties and promoted the migration of oxygen species. Consequently, V Mn -100-1 exhibited superior catalytic performance, stability, and moisture resistance (15%) for the complete oxidation of styrene. Additionally, designed experiments and density functional theory (DFT) calculations revealed that the dual vacancies improved oxygen species mobility and O 2 dissociation, while the co-existing defects and surplus O 2 mitigated the adverse effects of moisture. In situ diffuse reflectance infrared spectroscopy and DFT results indicated that the dual vacancies enhanced styrene activation and maleic anhydride decomposition. Thus, the rate-limiting steps were modified and the reaction process was optimized. This study provides new insights into dual-defect systems and offers a novel approach for designing high-efficiency catalysts for VOC degradation.
研究领域:
材料化学
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环境催化
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表面科学
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物理化学
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纳米催化
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理论计算化学
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产品关联
DOI
高影响因子
Advanced Materials Interfaces
·
2020
·Vol. 7
·期 12
·1902127
·
IF 4.948
Shiwei Liu,Kai Li,Tao Hu,Xiaodong Wu,Haiyong Ao,Youtao Xie,Xuebin Zheng
The osteoblast-function associated integrin–ligand interactions are known to be dependent on divalent cations, but there is scarce information about the effect of Ca 2+ and Mg 2+ adsorption properties of an implant surface on integrin α 5 β 1 –fibronectin interactions and the subsequent osteoblast behavior. Cation adsorption properties are closely associated with the extent of structural defects in materials. Here, the birnessite-type MnO 2 coatings with different amounts of manganese vacancy ( V Mn ) are prepared on Ti substrates via hydrothermal treatment (denoted as 1M100-Ti, 5M100-Ti, and 5M120-Ti). The 5M120-Ti surface with hierarchical flower-like structure and the most stacked [MnO 6 ] layers possess the highest V Mn content, which is determined by the ratios of Mn 3+ /Mn 4+ and K/Mn. The increased V Mn content enhances the Ca 2+ and Mg 2+ adsorption properties of the birnessite coatings. When immersed in Ca 2+ /Mg 2+ aqueous solution, the birnessite coatings significantly promote fibronectin adsorption and the exposure of cell-binding domains on adsorbed fibronectin with 5M120-Ti showing the greatest enhancement. Accordingly, the 5M120-Ti surface provides more α 5 β 1 -integrin-specific instructions to MC3T3-E1 preosteoblasts capable of enhancing spreading and osteoblastic differentiation compared to two other samples. This study may provide a prospective approach of modulation of integrin–ligand interactions for controlling cell behavior by adjusting metal vacancies in metal oxides coatings.
研究领域:
材料科学
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生物医学工程
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细胞生物学
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DOI
高影响因子
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