GEOCHIMICA ET COSMOCHIMICA ACTA
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2021
·
IF 5.01
Jing Liu,Sayako Inoué,Runliang Zhu,Hongping He,Michael F. Hochella
It is recognized that different facets of minerals vary distinctively in their chemical reactivity with aqueous solutions. However, detailed molecular and atomistic understandings of these phenomena are relatively limited. This study investigated the interaction of aqueous Mn 2+ and dissolved oxygen on various facets of two morphology-types of iron oxide (hematite) nanocrystals. These interactions result in the oxidation of Mn(II) and heterogeneous growth of Mn(II)/Mn(III) and Mn(III) oxides. The nanoscale morphology and atomic structure of the manganese oxide products were characterized in detail. Our results, for the first time, directly demonstrate the facet-specific oxidation of Mn(II) and nucleation of Mn(II/III) oxides, followed by their epitaxial growth on hematite. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron diffraction measurements reveal the growth of MnO x nanowires on {1 1 3} of hematite nanoplates (HNP) and {0 1 2} facets of hematite nanocubes (HNC), while the basal {0 0 1} facets on the HNP particles do not produce precipitates. The average oxidation states of the MnO x on HNP and HNC determined using electron energy-loss spectroscopy (EELS) show that both Mn(II) and Mn(III) are present. The mineral composition and growth mechanisms of MnO x catalyzed by HNP and HNC are similar. High-resolution TEM analysis reveals the presence of both hausmannite and manganite on HNP and HNC. The crystallographic relationship between the heterogeneously formed manganite with hematite, which has not been reported before, proves that hematite provides reaction sites and can function as an atomic template for the formation of MnO x nanowires. These findings advance our understanding of the redox chemistry and heterogeneous growth of minerals as controlled by the surficial structure of the substrate mineral. This has important geochemical implications as the catalytic growth of less common, highly reactive phases like MnO x are known to be consequential in complex natural and anthropogenic environments.
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Journal of Physical Chemistry C
·
2021
·
IF 4.126
Jonathan M. Wong,Jie Xu,Ruizhong Zhang,Kenneth Chu,Zhifeng Ding,Lijia Liu
Electrochemiluminescence (ECL) of Mn-doped CsPbCl3 perovskite quantum dot (MPQ) films was investigated for the first time. The electrochemical properties of the perovskite quantum dots are probed by cyclic voltammetry and spooling ECL spectroscopy. It has been discovered that the ECL of the MPQ/benzoyl peroxide coreactant system proceeds through two channels: an energy transfer process from the band-edge exciton to Mn2+, producing emission centered at 595 nm from Mn2+ d–d transition, and a second emission peak centered at 660 nm, which is of a surface-state origin. This observation is drastically different from the frequently reported photoluminescence (PL) of MPQ, which contains dual emission from the host and the dopant, respectively. ECL of the undoped CsPbCl3 (UPQ) was also investigated, and the presence of the 660 nm peak further supports our proposed surface-state emission scheme.
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WATER RESEARCH
·
2021
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IF 11.236
Yuan Gao,Yang Zhou,Su-Yan Pang,Jin Jiang,Yong-Ming Shen,Yang Song,Jie-Bin Duan,Qin Guo
In recent years, the activation of persulfates (peroxydisulfate (PDS) and peroxymonosulfate (PMS)) via transition metal ions for contaminants degradation has received extensive attention in water treatment. There has been growing interest on the mechanism (radical versus non-radical pathway) of activation processes. Interestingly, in contrast to copper, iron or cobalt ions regarded as effective activators for persulfates, manganese ion (Mn(II)) is inefficient for persulfates activation. Inspired by the enhanced stability of manganese species by ligands, this study for the first time systematically investigated the Mn(II)/persulfates with different ligands as a novel oxidation technology. UV-vis spectrometry, chemical probing method and mass spectrometry were used to explore the reactive intermediate (free radical versus high-valent manganese species) therein. It was surprisingly found that the oxidation efficiency of Mn(II)/ligand/persulfates system was highly dependent on the nature of persulfates and ligands. Mn(II) chelated by amino ligands such as ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetate (NTA) could efficiently trigger the oxidation of contaminants (e.g., recalcitrant compounds nitrophenol, benzoic acid and atrazine) by PMS , suggesting a promising Mn(II)/ligand/PMS technology for environmental decontamination especially under manganese-rich conditions. High-valent Mn species (Mn(V)) but not free radicals was demonstrated to be the dominant reactive intermediate, where Mn(III) species played a vital role in Mn(V) generation. The formation of Mn(III) species was found to be affected by the reactivity of persulfates and the type of ligands, thus influencing its further oxidation to Mn(V) species. This study presents a new oxidation process based on the combination of PMS and Mn(II) complex and broadens the knowledge of persulfates activation as well as manganese chemistry for decontamination in water treatment.
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PubMed
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2021
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IF 4.539
Zipeng Feng,Yanwei Sui,Zhi Sun,Jiqiu Qi,Fuxiang Wei,Yaojian Ren,Zhenzhen Zhan,Meihua Zhou,Dongmei Meng,Lijun Zhang,Lan Ma,Qun Wang
Developing cost-effective and binder-free bifunctional electrocatalysts to boost the hydrogen and oxygen evolution reactions are crucial for overall water splitting. In this work, three-dimensional hierarchical Mn-Co-P/NF electrodes on nickel foam are synthesized by electrodeposition and chemical vapor deposition (CVD) firstly. Provide an excellent and controllable synthesis method by controlling the electrodeposition time and phosphating temperature. The Mn-Co-P composite exhibits the characteristics of vertically grown porous nanosheets, which can effectively expose the active sites. Benefit from the rational design with in-situ growth of functional materials and the unique structure, the Mn-Co-P/NF presents excellent electrocatalytic activities and stability with lower overpotentials of 63 mV and 310 mV to deliver 10 mA cm −2 for hydrogen evolution reaction (HER) and 10 mA cm −2 for oxygen evolution reaction (OER), respectively. Moreover, when directly used as a positive electrode and a negative electrode to form an electrocatalytic device to complete the overall water splitting, Mn-Co-P/NF merely requires a small cell voltage of 1.70 V to obtain 20 mA cm −2 . This work offers a controllable method to design and synthesize highly efficient and stable transition metal phosphide catalysts for overall water splitting and other catalytic fields.
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JOURNAL OF RARE EARTHS
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2020
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IF 3.104
Baohuai Zhao,Rui Ran,Liu Yang,Xiaodong Wu,Zhichun Si,Duan Weng
A series of La 1– x Ce x MnO 3+ δ ( x = 0, 0.05, 0.1, 0.2, and 0.3) perovskites and Mn–Ce mixed oxides were prepared. Their physico-chemical properties were systematically characterized and the NO oxidation activities of the catalysts were investigated. The La 0.9 Ce 0.1 MnO 3+ δ has the best activity among all of the catalysts, with a maximum NO conversion of 85% at 300 °C. The characterization results indicate that the doping of Ce improves the properties of the perovskites in terms of the specific surface area, the average valence state of Mn ions, the number of reactive oxygen species and the NO x desorption behaviors. The Mn–Ce mixed oxide calcined at 500 °C shows a similar NO oxidation activity with La 0.9 Ce 0.1 MnO 3+ δ . However, the activity of the mixed oxide obtained at 750 °C decreases a lot, which results from the loss of active sites and active oxygen species.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
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IF 4.939
Li Wang,Lili Cui,Xin Ge,Nailin Yue,Xingquan He,Wei Zhang,Tewodros Asefa
Developing efficient nonprecious electrocatalysts that can drive the oxygen electrode reactions in zinc-air batteries (ZABs) is important but remains challenging. In this work, novel materials comprising Mn/Cu nanoclusters-grafted N-doped carbon nanotubes are synthesized by preparing and then pyrolyzing Mn/Cu polyphthalocyanine-encapsulated carbon nanotubes (CNTs), followed by treating the products with acidic solution. The materials are named CNTs@(Mn,Cu)PPc-T, where T denotes the pyrolysis temperature in °C, and they are demonstrated to serve as efficient oxygen electrode catalysts for zinc-air batteries (ZABs). Among them, the one synthesized at 900 °C, CNTs@(Mn,Cu)PPc-900, requires more positive onset and half-wave potentials for reduction of oxygen and a low overpotential for the evolution of oxygen. A rechargeable ZAB assembled with CNTs@(Mn,Cu)PPc-900 electrocatalyst delivers a high power density (158.5 mW cm −2 ) and displays an excellent stability in 200 cycles of charge/discharge (in over 33 h). Such performance is even superior to that of a ZAB containing the benchmark Pt/C + RuO 2 catalyst as an air cathode under identical testing condition.
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JOURNAL OF THE ELECTROCHEMICAL SOCIETY
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2020
·Vol. 167
·期 10
·104501
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IF 3.721
Shengliang Wei,Yuqing Miao
The Mn-doped Ni(OH)2 nanostructures were obtained by a simple ion-exchange hydrothermal method. The as-prepared materials were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) for their morphological, composition and structural properties. As a material for modified electrodes, electrochemical tests demonstrate that the methanol oxidation peak current density of Mn-doped Ni(OH)2 nanostructures reached 14.18 mA cm−2 at 0.596 V (vs Ag/AgCl) in NaOH electrolyte. Similarly, the Mn-doped Ni(OH)2 nanostructures also maintained good electrocatalytic stability during the term of 36,000 s. The improvement of electrochemical performance is related to the introduction of Mn element in Ni(OH)2. It may promote Ni in the Mn-doped Ni(OH)2 nanostructures to carry the lower electron density and the higher oxidation state which may be responsible for the better performance toward methanol oxidation.
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NANO
·
2019
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IF 1.293
Zhenping Liu,Xianfeng Wang,Jingzhou Hou,Danqun Huo,Changjun Hou
An innovative phosphorescence probe based on Mn-doped ZnS quantum dots (Mn:ZnS QDs) was developed for selective detection of chloramphenicol (CAP) via inner-filter effect (IFE). Mn:ZnS QDs were synthesized by water method and modified with L-Cysteine for better stability, and the average diameter of the nanometer particle was 3.8 nm. With the excitation wavelength at 289 nm, the strong phosphorescence of Mn:ZnS QDs can be emitted at 583 nm. The excitation spectrum of Mn:ZnS QDs was substantially overlapped with the absorption spectrum of the target CAP. The excited light of Mn:ZnS QDs can be absorbed partially by CAP when they coexist, the phosphorescence intensity decreased with the increasing concentration of CAP, and it has a good linear relationship. Under optimal conditions, the linear relational concentration range achieved four orders of magnitude from 25 to 1 . 2 × 1 0 5 ng ⋅ mL − 1 ( R 2 = 0 . 9 9 9 ), with a detection limit (LOD; S ∕ N = 3 ) down to 0.81 ng ⋅ mL − 1 . The simple, rapid and low cost IFE phosphorescent probe exhibited satisfactory recoveries ranging from 88.9% to 98.5% for CAP analysis in spiked honey, which shows a potential for routine screening of CAP in ensuring the food safety.
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Food Chemistry-X
·
2026
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IF 9.2
Jiaxuan Tang,Wenru Wang,Weina Yu,Qiuran Wang,Yunxuan Li,Conglin Feng,Jianhang Yang,Yifei Pan,Xiaodong Cao,Shudong He,Yuhan Sun,Yongkang Ye,Haisong Zheng
Herein, Mn-doped carbon dots (Mn-CDs) were prepared and used as a reducing agent to reduce PtCl 6 2− to platinum nanoparticles (Pt NPs), forming a stable nanozyme of Mn-CDs@Pt NPs. The prepared Mn-CDs@Pt nanozyme exhibited high oxidase-like activity toward the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) with a low Michaelis-Menten constant ( K m ) value of 0.0545 mM and a high maximum initial velocity ( V max ) value of 3.42 × 10 −7 M s −1 . By exploiting the excellent oxidase-like activity of Mn-CDs@Pt nanozyme and combining the thiol-ene Michael addition between glutathione (GSH) and acrylamide (AA), a sensitive colorimetric detection interface for AA was fabricated. Using UV–vis measurement, the colorimetric sensor for AA detection displayed a broad linear detection range from 0.05 to 5000 μM and a detection limit (LOD) of 0.0371 μM. In addition, a smartphone-assisted detection of AA yielded a linear range from 5 to 5000 μM with an LOD of 4.35 μM. The colorimetric sensor was applied for AA detection in real samples, achieving satisfactory recoveries in the range of 94.8–110.4%. Moreover, the detection results of AA in real samples were in good consistency with those detected using the standard method of HPLC, suggesting that the proposed colorimetric method possesses potential for AA detection in food safety and quality monitoring.
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CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Wei Wang,Zhulin Han,Haiwang Wang,Xinfang Wei,Ruixia Zhong,Jian Qi
In this paper, CoMn based nanowires were in-situ grown on foam nickel by hydrothermal method combined with calcination treatment, and a monolithic methane oxidation catalyst was obtained. The effects of hydrothermal temperature and calcination temperature on the crystal structure, micro morphology and catalytic performance of the catalysts were systematically studied. The results indicated that when the hydrothermal temperature was 160 °C and the calcination temperature was 350 °C, Mn doped Co 3 O 4 nanowires with uniform morphology can be obtained, accompanied by the appearance of CoMn 2 O 4 . The introduction of Mn ions caused lattice distortion of Co 3 O 4 , achieving the regulation of adsorbed oxygen and lattice oxygen. The monolithic MnCoO/NF–H-160 °C catalyst showed the best catalytic activity (T 90 = 414 °C) for lean methane catalytic oxidation, which even surpassed the noble metal based catalyst. Its excellent catalytic activity was due to the fact that the catalyst can expose more active sites, rich active oxygen and good mass transfer characteristics. This study provides a new approach for designing efficient monolithic catalysts and has significant potential for application and development in the field of organic waste gas treatment.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2023
·
IF 22.1
Yuan Li,Miao-Ying Chen,Bang-An Lu,Hao-Ran Wu,Jia-Nan Zhang
Although the Mn-N-C catalyst has low toxicity and high durability, its intense pH-dependent ORR activity is perplexing and prevents its commercial use in PEMFCs. Herein, we have developed a novel understanding of the role of hydrogen peroxide in the pH-dependent activity and stability of Mn-N-C catalysts. Instead of nitrogen protonation, the strong pH effects of ORR activity are caused by the much faster kinetics of the H 2 O 2 reduction reaction in alkaline medium than in acid, due to the lower dissociation energy of the HO-OH bond in alkaline environment. Regarding durability, the deactivation induced by H 2 O 2 demonstrates a strong pH dependence, primarily due to the differing intensities of reactive oxygen species at different pH values. Correspondingly, isopropanol effectively reduces Fenton reagents and increases the acid resistance of Mn-N-C sites. The present research provides a mechanistic understanding of pH effects and paves the way for the creation of more efficient catalysts.
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CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Ziyun Zhang,Hanghang Hui,Qian Chen,Zhiyuan Wang,Runguo Zheng,Hongyu Sun,Yanguo Liu
Mn-based layered oxides with high theoretical capacity are one of the most promising cathode materials for potassium-ion batteries. However, the Jahn-teller distortion of Mn 3+ in Mn-based layered cathodes always brings about harmful disordered structure and irreversible phase transition, resulting in severe degradation of electrochemical performance. Herein, we synthesized P3–K 0.5 Mn 0.6 Ni 0.2 M 0.2 O 2 (M = Fe, Co, FeCo) and systematically investigate the effect of component regulation on the layered structure and electrochemical properties. The P3–K 0.5 Mn 0.6 Ni 0.2 Co 0.2 O 2 exhibits a discharge capacity of 73.77 mAh g −1 , demonstrating an excellent capacity retention rate of 70.17 % after 120 cycles at 50 mA g −1 . In-depth analysis reveals that P3–K 0.5 Mn 0.6 Ni 0.2 Co 0.2 O 2 possesses a larger K + layer spacing, making the insertion/extraction of potassium ions become much easier. Furthermore, the introduction of Co into the transition metal layer enhances the content of Mn 4+ , thereby inhibiting Jahn-Teller distortion and improving structural stability. Especially, the P3–K 0.5 Mn 0.6 Ni 0.2 Co 0.2 O 2 shows a highly reversible single-phase solid solution reaction during the initial cycle, which means the detrimental phase transition of P3–O3 caused by Jahn-Teller effect is effectively suppressed. This work contributes to a better understanding of the effect of component design and regulation on the performance of the layered oxides cathode and provide insight into the design of high-performance cathode materials for potassium-ion batteries.
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