Nano Energy
·
2018
·
IF 13.12
Chunning Zhao,Meng Yu,Zhi Yang,Jieyu Liu,Shaohua Chen,Zhanglian Hong,Haijun Chen,Weichao Wang
Interface engineering is one of the key strategies to modify the intrinsic electronic structures of catalysts and consequently improve the electrochemical activity of the oxygen reduction reaction (ORR) in the cathodes of the energy conversion devices such as fuel cells and metal-air batteries. Herein, we proposed the mixed-phase mullite (A x Sm 1−x Mn 2 O 5-δ , x = 0–0.5, A=Ca, Sr, Ba), prepared by facile one-step co-precipitation method, to catalyze the oxygen reduction reaction (ORR). The X-ray diffraction (XRD) spectra show that each mixture includes three phases, i.e., mullite SmMn 2 O 5 , O-deficient perovskite AMnO 3-δ and MnO x . Atomic bonding interfaces are formed between SmMn 2 O 5 and AMnO 3-δ , based on the observations of the high resolution transmission electron microscopy (HRTEM). Among these different mixed-phase samples, we find that Ba x Sm 1−x Mn 2 O 5-δ /C exhibits the best ORR catalytic activity with the half-wave potential ~ 0.79 V (vs. RHE) and the highest stability over 20,000 s. This performance can be ascribed to the largest charge transfer from BaMnO 2.83 to SmMn 2 O 5 . Subsequently, partial Mn 4+ in mullite SmMn 2 O 5 phase are reduced to active sites Mn 3+ to achieve the e g unit occupancy in the interfacial depletion region . In comparison with the reactions over pure-phase mullite SmMn 2 O 5, these transferred electrons are involved into ORR and thus accelerate the proceeding. Our work thus provides insights into designing heterogeneous compound catalysts via interfacing engineering in the applications of the electrochemical oxygen reactions.
研究领域:
材料科学
·
电化学
·
能量转换装置
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DOI
高影响因子
Catalysis Science & Technology
·
2020
·Vol. 10
·期 6
·1941-1951
·
IF 5.721
Shaohua Chen,Hui Li,Yu Hao,Rui Chen,Tiehong Chen
A series of porous Mn-based oxides (mullite SmMn2O5, perovskite SmMnO3, spinel Mn3O4 and bixbyite Mn2O3) were systematically prepared and applied in ethanol and toluene catalytic oxidation. Among them, SmMn2O5 exhibited the highest catalytic activity, the best hydrothermal stability and the highest durability. Due to the different compositions and structures of the catalysts, the surface composition, Mn-valence state, reduction properties, and adsorption and desorption behavior of oxygen and ethanol were different as characterized by XPS, H2-TPR, O2-TPD and ethanol-TPD measurements. Based on the characterization results, the relationship between the catalyst structure (crystal and electronic structure) and catalytic activity was discussed in terms of their crystal field configurations and structures of the energy bands. The superior activity of SmMn2O5 could be attributed to dz2 orbital occupancy near the Fermi level determined by the Mn3+-centered pyramidal field, as well as the existence of a Mn3+–Mn3+ dimeric structure, which is critical for C–C bond cleavage.
研究领域:
材料科学
·
催化化学
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产品关联
DOI
高影响因子
ACS Catalysis
·
2023
·
IF 12.9
Yi Liu,Fanyu Wang,Fei Xie,Jiamin Zheng,Jintong Lan,Furong Guo,Yifei Sun,Lizhi Zhang,Xiao Liu
The degradation of chlorine-containing volatile organic compounds (Cl–VOCs) utilizing catalytic combustion technology is subject to the paradox of toxic byproduct formation and catalyst chlorine poisoning. Herein, a CaO-assisted strategy is proposed to resolve the awkward stuff for improving the catalytic combustion performance of chlorobenzene on SmMn2O5. The CaO-collaborated SmMn2O5 exhibits a significant decrease in T90 by 142 and 125 °C compared with unmodified and inert SiO2-composited SmMn2O5, respectively. The integrated characterization results confirm that CaO collaboration causes electron transfer from CaO to SmMn2O5, resulting in a reduction of the orbital overlap between Mn and O atoms to activate lattice oxygen (Olatt). The activated Olatt enables chlorobenzene to combust completely at a lower temperature of 275 °C at which toxic byproducts are not generated. Furthermore, the switching of the dechlorination site from SmMn2O5 to CaO avoids chlorine poisoning of active sites on SmMn2O5 and thus endows CaO-collaborated SmMn2O5 with prominent stability.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2025
·
IF 4.1
Tai-Shen Yang,Jie Wu,Jing Chi,Jin-Chao Cao
To enhance the synergistic catalytic effect of pyramid Mn 3+ and octahedral Mn 4+ dual crystal fields in SmMn 2 O 5 and improve its oxygen reduction reaction (ORR) performance, Ba-doped Sm 1-x Ba x Mn 2 O 5 (x = 0.1–0.5) catalysts were prepared by hydrothermal method. The substitution of partial Sm 3+ in SmMn 2 O 5 by Ba 2+ leads to the increase in the ratios of Mn 4+ /Mn 3+ and surface adsorbed oxygen/lattice oxygen on the surfaces of Sm 1-x Ba x Mn 2 O 5 . The increase in surface adsorbed oxygen content indicates stronger oxygen adsorption capacity, while the increase in Mn 4+ content facilitates synergistic catalysis of the dual crystal fields. Pyramid Mn 3+ acts as the active site to catalyze ORR, while the increase in octahedral Mn 4+ content enhances the catalytic activity of Mn 3+ by reducing the binding energy between Mn 3+ and oxygen-containing intermediates, weakening the Mn 3+ -O bond, and accelerating the decomposition of hydrogen peroxide generated by Mn 3+ during the ORR process. Sm 0.6 Ba 0.4 Mn 2 O 5 exhibits excellent ORR performance owing to the suitable Mn 4+ /Mn 3+ ratio on its surface, the half-wave potential reaches 0.77 V, higher than the 0.72 V of SmMn 2 O 5 , and the diffusion-limited current density increases from 3.50 mA·cm −2 for SmMn 2 O 5 to 5.03 mA·cm −2 . Moreover, the synergistic catalytic mechanism of the dual crystal fields was well discussed.
研究领域:
材料化学
·
电催化
·
能源材料
·
无机功能材料
·
固体化学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 77
·49091-49096
·
IF 3.108
Lina Xue,Ka Xiong,Haijun Chen,Kyeongjae Cho,Weichao Wang
Hydrothermal aging tests are important to carry out when evaluating the hydrothermal durability of heterogeneous catalysts in vehicle exhaust emission. Here, we explored the effect of aging on an efficient Mn-based mullite catalyst (SmMn2O5) of NO oxidation. The mullite catalyst was prepared via the hydrothermal method and was subsequently aged in air with a 10% H2O stream at 750 °C for 16 hours. The fresh and aged catalysts were structurally characterized using Powder X-ray diffraction(XRD), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), high resolution-transmission electron microscope (HR-TEM), Brunauer–Emmett–Teller (BET) and temperature programmed desorption (TPD). For the performance evaluations, the samples were placed into a U-shape reactor furnace, and NO and NO2 concentrations were in situ recorded with an NOx analyzer. In contrast to fresh mullite, the aged sample showed a 25 °C higher light-off temperature and 11% conversion loss at its maximum conversion temperature of 300 °C. O2-TPD of the aged sample displayed a large decrease of the desorption area, consistent with an ∼3-fold loss of the BET specific surface area. Moreover, HRTEM, XPS and Raman spectroscopy results together indicated that a small portion of the mullite decomposed into perovskite SmMnO3 and Mn2O3, which further reduced the total quantity of Mn active sites. The reduction of the BET surface area and mullite decomposition together caused the decrease of the catalytic performance. We therefore expect maintaining the specific surface area to be important for preventing the loss of catalytic performance during the hydrothermal aging process.
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DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2018
·
IF 6.945
Meng Yu,Qiliang Wei,Mingjie Wu,Jie Wu,Jieyu Liu,Gaixia Zhang,Shuhui Sun,Weichao Wang
Developing earth abundant and highly active electrocatalysts to overcome the sluggish oxygen reduction kinetics is one of the key toward the practical applications of air batteries with economic efficiency and high energy density. Herein, a shape-controlled synthesis of mullite SmMn 2 O 5 is achieved through a surfactant-free one-step hydrothermal method. SmMn 2 O 5 nanoparticles (SmMn 2 O 5 -NPs) and nanorods (SmMn 2 O 5 -NRs) are successfully synthesized and in half-cell tests, SmMn 2 O 5 -NRs perform enhanced oxygen reduction activity relative to SmMn 2 O 5 -NPs in terms of a more positive half-wave potential and reduced peroxide yield. Importantly, rechargeable zinc-air batteries constructed with SmMn 2 O 5 -NRs exhibit not only higher peak power density (217 mW cm −2 ) over commercial Pt/C catalyst (190 mW cm −2 ) but also excellent cycling stability during long-term charging-discharging test over 170 h. The facile synthesis of SmMn 2 O 5 -NRs together with the remarkable electrocatalytic performance endows mullite SmMn 2 O 5 with great promise in replacing the precious metal as future catalysts for air batteries.
研究领域:
材料科学
·
电化学
·
能量存储与转换
·
纳米材料
·
催化
✓ 已验证
DOI
高影响因子
POLYMER DEGRADATION AND STABILITY
·
2026
·
IF 8.1
Chaojun Yang,Zijian Feng,Zhe Dong,Yu Li
The development of polymer materials with flame-retardant and microwave-absorbing properties reduced fire risks and mitigated electromagnetic interference, representing an important direction in advanced materials research. In this work, La x Sm 1-x Mn 2 O 5 (xLSMO) mullite with varying La doping levels (molar ratio, x = 0.1, 0.3, 0.5) was synthesized via a co-precipitation method, and the effects of LSMO on the flame-retardant and microwave-absorbing properties of epoxy resin (EP) were investigated. The results demonstrated that LSMO exhibited excellent catalytic charring ability and a pronounced nucleating effect, effectively enhancing the compactness and strength of the char layer and thereby improving the fire safety of EP. When the La doping level was 0.3 and the LSMO loading in EP was 1wt%, the limiting oxygen index (LOI) increased from 24.1% to 32.3%, and a V-1 rating was achieved in the UL-94 test. The peak heat release rate (PHRR) and total heat release (THR) were reduced by 45.32% and 32.69%, respectively. In addition, the incorporation of LSMO endowed EP with favorable electromagnetic wave absorption capability, with a minimum reflection loss reaching −36.87 dB in the frequency range of 1–18 GHz. Therefore, the EP/LSMO composites exhibited considerable potential as multifunctional integrated materials in the fields of public safety and electromagnetic protection technology.
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产品关联
DOI
高影响因子
Materials
·
2024
·Vol. 17
·期 11
·2490
·
IF 3.1
Hui Chen,Qi Chen,Xiaomin Hu,Chenyu Ding,Lihong Huang,Ning Wang
The x%Ni/Sm2O3-MnO (x = 0, 10, 15, 20) catalysts derived from SmMn2O5mullite were prepared by solution combustion and impregnation method; auto-thermal reforming (ATR) of acetic acid (HAc) for hydrogen production was used to explore the metal-support effect induced by Ni loadings on the catalytic reforming activity and product distribution. The 15%Ni/Sm2O3-MnO catalyst exhibited optimal catalytic performance, which can be due to the appropriate Ni loading inducing a strong metal–support interaction to form a stable Ni/Sm2O3-MnO active center, while side reactions, such as methanation and ketonization, were well suppressed. According to characterizations, Sm2O3-MnO mixed oxides derived from SmMn2O5mullite were formed with oxygen vacancies; nevertheless, loading of Ni metal further promoted the formation of oxygen vacancies, thus enhancing adsorption and activation of oxygen-containing intermediate species and resulting in higher reactivity with HAc conversion near 100% and hydrogen yield at 2.62 mol-H2/mol-HAc.
研究领域:
催化化学
·
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Today Communications
·
2026
·
IF 4.9
Xingcan Lu,Shuaijie Li,Zijian Feng,Xuan Wang,Ze Chen,Chaojun Yang,Songlin Chen,Shaoyang Liu,Yu Li
Epoxy resin-hollow glass microsphere composites (EHC) exhibit low density and excellent mechanical properties, making them promising candidates for marine/aerospace applications. However, their high flammability severely restricts broader use. To improve flame retardancy while maintaining low density, ammonium polyphosphate-coated hollow glass microspheres (APP-HGM) were utilized to fabricate flame-retardant epoxy composites (EAHC). EAHC achieved improved flame retardancy and maintained low density, but it suffered from insufficient flame-retardant efficiency and notable mechanical degradation. To address these drawbacks, SmMn 2 O 5 mullite nanoparticles (SMO) were further incorporated to fabricate the multi-component flame-retardant epoxy composite (SMO-EAHC). Systematic characterizations including thermogravimetric analysis (TG), limiting oxygen index (LOI), vertical burning (UL-94) and cone calorimeter test confirmed that APP-HGM serves as both a flame-retardant filler and a lightweight matrix component, while SMO catalyzes the decomposition of APP and promotes the formation of compact char layers. SMO-EAHC achieved a LOI of 27.6% and a UL-94 V-1 rating, and presented remarkable reductions of 58.81%, 38.67%, 73.65% and 62.96% in peak heat release rate (pHRR), total heat release (THR), peak smoke production rate (pSPR) and total smoke production (TSP) compared with unmodified EHC. Meanwhile, SMO-EAHC exhibited a compressive strength of 23.84 MPa, representing a 32.08% improvement relative to EAHC, while maintaining a low density of 0.66 g/cm³ . In summary, this work proposes a targeted two-step modification strategy, involving APP-HGM functionalization followed by SMO complementation, to address the flammability of EHC. This strategy realizes the balanced integration of flame retardancy, lightweight characteristic and pressure resistance, providing technical support for the application of polymer composites in extreme environments.
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产品关联
DOI
高影响因子
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