查找使用阿拉丁产品的科研文献

Superior bifunctional oxygen electrocatalysts based on Co2MnO4 with mixed site occupancy, Mn-rich surfaces and twin defects

Jing Li,Xiyu He,Yunzhu Du,Min Jiang,Qiaodan Hu,Jiewei Yin,Fan Yang,Junliang Zhang

Co/Mn-based spinel oxides are promising electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), however, it is challenging to achieve high activities for ORR and OER simultaneously in one composition. Here, we report Co 2 MnO 4 (C2M) with Mn-rich surfaces and abundant twin defects synthesized by a simple coprecipitation and annealing route, which exhibits excellent ORR activity (half-wave potential E 1/2  = 0.830 V), long ORR durability (91% current retained after 12 h-chronoamperometry test at 0.45 V vs. RHE) and a low Δ E  = 0.767 V between E 1/2 and E 10 mA/cm 2 in alkaline electrolyte, which enables its excellent performances in rechargeable Zn-air batteries showing a high peak energy density of 136 mW/cm 2 and a large specific capacity of 809.4 mAh/g Zn . Combining comprehensive experimental investigations and DFT simulations, we reveal that the Mn-rich surfaces benefit bridge adsorption of O 2 to promote the 4-electron reaction pathway in ORR, and the mixed site occupancy in the crystal structure induces Mn/Co-O orbital hybridizations to form an impurity energy level in the band gap to facilitate charge transfer. Furthermore, the bifunctional performance and the ORR durability can be further enhanced by acid treatment to show a lower Δ E  = 0.750 V and to retain 98.5% ORR current in 12 h. This work provides not only a promising bifunctional electrocatalyst but also a new perspective of exploring simple synthesis method suitable for mass-producible electrocatalysts with highly active surfaces.

An easy CTAB-assisted path towards bayberry-like Ni–Co–Mn ternary hydroxide with enhancing supercapacitor performance

Huiling Zhu,Kai Wang,Yao Qi,Ruixin Li,Jianxu Ding,Rui Liu

In this study, we synthesized a bayberry-like Ni–Co–Mn ternary hydroxide with a secondary nanoneedle structure using a modified and cost-effective hydrothermal process assisted by the surfactant cetyltrimethylammonium bromide (CTAB). The incorporation of CTAB and graphene in the preparation process significantly enhances the electrochemical performance of NiCoMn–OH. The achieved results are truly impressive, with a high specific capacity of 1450 ​F ​g −1 and an outstanding capacity retention of 52.57% over 5000 cycles. The superior performance could be attributed to the specific bayberry-like microstructure with high effective specific surface area, which allowed for facile and rapid transport of ions and electrons. Moreover, the synergistic effect of CTAB and graphene proved to be crucial in stabilizing the Co 2+ and Mn 2+ ions within the ternary hydroxide structure. We developed a hybrid capacitor using a NiCoMn–OH-CTAB/Graphene composite electrode and an active electrode, which delivered a superior energy density of 50.79 ​Wh kg −1 at a power density of 400 ​W ​kg −1 and a cycling stability of 60.37% after 10000 cycles. These results indicate that the NiCoMn–OH-CTAB/Graphene composite electrode has great potential as an electrode material for energy storage devices.

Engineering Mn–Nx sites on porous carbon via molecular assembly strategy for long-life zinc-air batteries

Zehui Wang,Daijie Deng,Huan Wang,Suqin Wu,Linhua Zhu,Li Xu,Henan Li

Nitrogen-coordinated manganese atoms on carbon materials denoted as Mn N C, serve as the highly active non-precious metal electrocatalysts for oxygen reduction reaction (ORR) in zinc-air batteries (ZABs). Nonetheless, a significant challenge arises from the tendency of Mn atoms to aggregate during heat treatment, thereby compromising ORR performance in ZABs. In this work, the molecular assembly strategy based on the hydrogen bond interaction was employed to fabricate the Mn N C electrocatalyst . This approach promotes the dispersion of Mn atoms, creating abundant Mn–N x active sites. Furthermore, the resulting three-dimensional porous nanostructure, formed by molecular assembly, significantly enhances accessibility to the Mn–N x active sites. The porous nanostructure not only shortens the diffusion path of reactants and charges but also improves mass transfer. The Mn N C exhibits impressive ORR catalytic performance with a half-wave potential of 0.90 V (vs. RHE). The liquid-type ZAB based on Mn N C displays a high specific capacity of 816.6 mAh/g and an extended charge–discharge cycle life of 1000 h. Quasi-solid-state ZAB based on Mn N C can operate stably for 24 h. This work presents an effective strategy to synthesize transition metal-nitrogen-carbon (M N C) electrocatalysts tailored for long-life zinc-air battery.

Catalytic oxidation of ethyl acetate over Y (Y = Cu, Mn, Co)-modified CeO2 derived from Ce-MOF

Lirong Lv,Zhongguo Zhang,Sheng Wang,Yue Shan,Liangliang Wang,Tongzhou Xu,Peiran He

A series of Y Ce catalysts were prepared using Y-loaded (Y = Cu, Co, Mn) Ce-based metal–organic framework as a precursor. Mn-loaded CeO 2 exhibited significantly better catalytic activity in the catalytic oxidation of ethyl acetate (EA) than noble metal catalyst. The relationship between the physicochemical properties of Y Ce catalysts and catalytic activity was studied by different characterization methods. The enhanced catalytic activity was attributed to the strong interaction between the transition metals and Ce, high specific surface area, abundant lattice defects, more oxygen vacacies and higher O latt /(O latt  + O ads  + O w ) molar ratios. The main intermediates in the oxidation of EA were ethanol, acetic acid, acetone, acetaldehyde and diethyl ether.

A multichromatic colorimetric detection method for Vibrio parahaemolyticus based on Fe3O4-Zn-Mn nanoenzyme and dual substrates

Wenteng Qiao,Luliang Wang,Kun Yang,Yushen Liu,Quanwen Liu,Feng Yin

Mn-Enhanced Cobalt Silicate-Activated Peroxymonosulfate for Tetracycline Degradation: Inheriting Merit and Offsetting Deficiency of Oxygen Vacancies

Linlin Su,Lulu Long,Wending Wang,Zhenshuang Kuang,Xinyu Zhou,Chao Chen,Min Xu,Yan He,Gang Yang

Recently, the merits of Vo in catalytic areas were studied in detail, and the deficiency of Vo has also attracted much attention. However, when exploring the enhanced mechanism of bimetals for PMS activation, the effect of bimetals on the deficiency of Vo was usually ignored, especially in some Vo-rich bimetallic systems. Herein, the Co–Mn bimetallic silicate system was constructed to elucidate the effect and mechanism. MnCoSi has an edge over CoSi in the degradation performance of TC (0.02325 min–1 up to 0.07952 min–1). The result was assignable to the fact that the introduction of Mn brought more Vo and enhanced the positive effect of Vo. More importantly, the formation of heterogeneous active sites enhanced the adsorption of metal sites to PMS and compensated for the deficiency of Vo. This study enriched the enhancement mechanism of bimetallic systems and provided a theoretical basis for the optimization of catalysts rich in Vo.

What is the role of Mn/Al/Pt for ZSM-11 being a good catalytic oxidation catalyst?

Qingjun Yu,Wenjing Wu,Jinghui Wei,Jie Zhang,Shunzheng Zhao,Xiaolong Tang,Honghong Yi

Catalytic combustion is one of the most effective technologies applied to volatile organic compounds (VOCs) emission control, in which zeolites have been regarded as a unique support or even a catalyst due to their unique shape & size features as well as the interaction between the zeolitic structural groups and the extraneous metal species. Particularly, Mn-based zeolites have attracted great attention as a promising catalyst for their superior redox ability on account of mixed valent properties. In this work, a series of Mn-contained samples with different compositions were synthesized to investigate the role of Al and Mn in zeolite for catalytically combusting VOCs. As redox active sites, Mn is well dispersed in the form of oligomeric Mn oxide clusters on the surface to optimize catalysis. With Al and Mn introduced into zeolite simultaneously, more defects for the activation of adsorbed oxygen appeared on superficial MnO x , but Al prevented Mn being incorporated in ZSM-11(MEL) distinctly, which is a principal factor affecting the catalytic activity . Additionally, Pt was introduced to further enhance the catalytic performance, whose function in Mn-MEL was also clarified in detail via XPS and other characterization techniques. Results demonstrated that appropriate Mn/Pt ratio could create suitable surface morphology (the interface of Pt-MnO x ) for the adsorption of oxygen species via the synergistic catalytic effect caused by Pt and Mn.

Redox on Mn-Ce interface and its effects on low temperature selective catalytic reduction for NOx removal

Fengyuan Liu,Junqi Li,Hong Yong Sohn,Chaoyi Chen,Jian Yang,Xudong Liu,Yuanpei Lan,Wei Zhang,Qin Wang,Li Liu

The objective of this work was to clearly elucidate the interactions on Mn-Ce interface and understand how they affect low temperature selective catalytic reduction (SCR) for NO x removal. In this work, three Mn-Ce catalysts in similar particle size and morphology with different Mn-Ce interface areas were prepared. MnO 2 @CeO 2 -F had the tightest and largest amount of Mn-Ce interfaces compared with MnO 2 @CeO 2 -P and MnO 2 -CeO 2 -M, and also exhibited the highest NO conversion degree at 100–150 °C as well as the strongest activity of Mn species and lowest generation of N 2 O. The TG-DTG, XPS and electrochemical impedance spectroscopy results proved the redox of Ce 4+ + Mn 3+ ↔ Ce 3+ + Mn 4+ on the Mn-Ce interface, and MnO 2 @CeO 2 -F had the highest Mn 4+ , Ce 3+ , O α concentrations. The results of the study on the redox reactions during the NH 3 -SCR process provided powerful evidence of the Mn 4+ /Mn 3+ and Ce 3+ /Ce 4+ recycles that are important for low temperature NH 3 -SCR process. Moreover, the Mn-Ce interface was directly proved to benefit the surface acid sites, redox ability, and activity of the adsorbed intermediates. Both the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) reaction mechanisms were observed in the SCR reaction with prepared Mn-Ce materials, where “fast SCR” can be observed with MnO 2 @CeO 2 -F. Moreover, the Mn-Ce interface also lowers the activation energy of the low-temperature SCR process, with MnO 2 @CeO 2 -F having the lowest activation energy. The results from this work offered powerful evidences for the interactions of Mn/Ce redox at the Mn-Ce interface and elucidated clear understanding of the effects of Mn-Ce redox on low-temperature SCR process, which is expected to promote the NO x removal process.

Enhanced PMS Activation by Highly Dispersed Mn-Ce Bimetallic Oxide on Carbon Nanotubes for Degradation of Phenol

Jing Wang,Quanfeng Wang,Pei Gao,Da Sun,Libo Jin,Li Ma,Lan Yang,Jujiao Zhao

Peroxymonosulfate (PMS) activation is an intriguing technology for refractory organic pollutant removal in wastewater treatment. Herein, a highly dispersed Mn-Ce bimetallic oxide on carbon nanotubes (MCC) was synthesized and applied to catalyze PMS for the degradation of phenol. The material was well characterized using a transmission electron microscope (TEM), N2adsorption–desorption isotherms, X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The synthesized MCC showed superior activity for PMS activation. Thekvalue of phenol removal with MCC is 0.135 min−1, which is greatly superior to that of CNT (6.17 × 10−5min−1) and Mn-Ce bimetallic oxide (3.18 × 10−4min−1). Electron paramagnetic resonance (EPR), along with radical quenching experiments, revealed that the activation of PMS by MCC for phenol degradation involves both radical and non-radical reaction pathways. Moreover, a synergic effect between Mn-Ce bimetallic oxide and CNT was identified to be responsible for the outstanding catalytic activity.Keywords:PMS activation;Mn-Ce bimetallic oxide;CNT;synergic effect

Fabrication of Co-Fe-Mn composites with a mixed-dimensional structure for applications in high-performance supercapacitors

Haiying Li,Shishuai Sun,Wen Cui,Xiaolan Li,Chuanjia Kou,Zhihui Xu,Zhihui Zhang

Reasonably regulating the dimensionality and interface of an electrode material can effectively improve its surface chemical reactivity, charge transfer rate, and ion transport performance, which is crucial to solving several problems with supercapacitors , including low energy density and poor cycle stability. The multidimensional hybrid morphology of Co-Fe carbonate hydroxide (CH) coupled with Co-Mn layered double hydroxide (LDH) is generated directly on the nickel foam substrate by a two-stage process. The prepared multidimensional hybrid materials with pore morphology with the synergistic effect of 1D nanorods , 2D nanosheets , and 3D “porous coral” not only ensure sufficient contact between the electrolyte and electrode material but also enhance the charge transfer and ion diffusion of the electrolyte. The strong coupling effect of Co, Fe, and Mn metals between the heterojunction surface can produce various ionic valence states and high conductivities, resulting in increased redox activity, which thus improves the electrochemical performance. The results of the electrochemical performance test show that when the current density is 10 mA cm −2 , the high area-specific capacitance of 7.33 F cm −2 is two times (3.85 F cm −2 ) that of a Co-Fe CH electrode and five times that of a Co CH electrode. The quasi-solid state asymmetric supercapacitor with a Co-Fe-Mn positive electrode and an active carbon negative electrode displays an energy density of 0.723 mWh cm −2 at a power density of 8.53 mW cm −2 . After 5500 cycles, the apparatus exhibits 101.72 % of the initial capacitance, which can effectively drive small electrical appliances. The results indicate that the supercapacitor exhibits excellent cycle stability and application potential in energy storage.

Two inorganic-organic hybrid complexes based on Mn(II) and Bi(III): Synthesis, crystal structure, and properties

Si-Hui Tan,Zhao-Hui Chen,Xi Jiang,Guo-Qing Zhong

Two manganese(II) and bismuth(III) complexes of the formulae [Mn(H 2 O) 6 ]·H 2 bptc ( 1 ) and (H 2 bipy) 2 [Bi 2 Cl 10 ]∙2H 2 O ( 2 ) (H 4 bptc = 3,3′,4,4′-biphenyltetracarboxylic acid, bipy  = 4,4′-bipyridine) were synthesized. The complexes were characterized by elemental analyses, single-crystal X-ray diffraction, powder X-ray diffraction, infrared spectra, and thermal analyses. Structurally, 1 is a mononuclear complex with a triclinic space group P 1 ‾ . 2 is a dinuclear complex and it is built of two Bi 3+ ion cores bridged through two Cl − ions. Furthermore, the result of fluorescence showed that 1 had fluorescent property. And the nanometer manganese oxide was prepared using 1 as a precursor. In addition, the photocatalytic activity of 2 on the degradation of Rhodamine B (RhB) was investigated and a possible photocatalytic mechanism was proposed.

Aerobic oxidation of 5‑hydroxymethylfurfural to 2,5-furandicarboxylic acid over Co/Mn-lignin coordination complexes-derived catalysts

Hua Zhou,Huanghui Xu,Yun Liu

Deriving more valuable products from renewable lignocellulosic biomass is attractive but still remains major challenges, the insufficient lignin valorization is considered as one of the main obstacles. Here, we report a novel catalyst comprised of cobalt nanoparticles (NPs) encapsulated in graphitic carbon tailored with manganese and nitrogen heteroatoms (Co-Mn/N@C), fabricated by pyrolyzing a mixture of Co/Mn-lignin complex and dicyandiamide. The as-synthesized Co-Mn/N@C catalyst exhibits excellent activity and recyclability for oxidizing biomass-derived 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA) in aqueous system using O 2 as oxidant. The structure-performance relations of the catalyst are investigated, suggesting that Mn/N-doped carbon can activate the reactivity of Co NPs for HMF oxidation by tuning the electronic structure of embedded metal NPs. Additionally, isotopic labelling experiments reveal the role of water and O 2 for FDCA production using Co-Mn/N@C as catalyst. This work not only demonstrates the integrated biorefinery strategy, but also provides a new approach for sustainable, low-cost heterogenous catalysts preparation.