查找使用阿拉丁产品的科研文献

Zn-Mn-Mg alloy with superior mechanical properties and antibacterial performance

Tang Yubo,Huang Sheng,Chen Wei-chih,A Garu,Linghu Xitao,Wa Qingde,Huang Shuai,Chen Jian

Zn-Mn alloys are particularly promising biodegradable implant materials, but they are plagued by poor mechanical performance. In this work, a Zn-Mn alloy with ultrahigh strength and excellent ductility was achieved through addition of trace Mg (0.1 wt%) and equal channel angular pressing (ECAP). Specifically, the ECAP processed Zn-0.5Mn-0.1 Mg alloy exhibits an ultimate tensile strength (UTS) of 428 MPa, which is highest ever achieved in Zn-Mn-based alloys, along with a good elongation (EL) of 39%. In addition, the alloy exhibits excellent antibacterial performance against Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ). Trace Mg addition results in the formation of Mg 2 Zn 11 and MgZn 2 nano-precipitates in the alloy, which effectively pins grain growth during dynamic recrystallization (DRX) and postpones the inverse Hall–Petch relation. Consequently, the alloy possesses quite fine grains of an average grain size (AGS) of 0.71 μm, much smaller than that of its counterpart without Mg (AGS = 2.54 μm). The ultrahigh strength of the alloy is mainly ascribed to grain boundary strengthening and precipitation strengthening. The remarkable ductility of the alloy is related to deformation twinning suppression, pyramidal < c + a > slip activation, and low dislocation density.

Self-supported Fe,Mn-CoCH/NF electrocatalyst for oxygen evolution reaction

Huiyu Sun,Xinyu Gu,Jun Yu,Nannan Zhang,Zhengying Wu,Jiawei Qiang,Zhongjie Song,Yukou Du

The oxygen evolution reaction (OER), as the core half-reaction in water electrolysis (WE), plays a decisive role in determining the overall efficiency of hydrogen production. Cobalt carbonate hydroxide (CoCH) has recently emerged as a attractive material for alkaline OER due to its robust structural stability. In this study, urchin-like CoCH was employed as a precursor template to synthesize Fe and Mn co-modified CoCH catalyst on nickel foam (NF) through Mn-doping and surface Fe-modification strategies (recorded as Fe,Mn-CoCH/NF). This optimized hierarchical structure enhanced the exposure of active sites and facilitated faster electron/mass transport paths. The incorporation of Fe and Mn effectively regulated the position of d-band center and facilitated a more efficient lattice oxygen mechanism (LOM) for OER, thereby enhancing the intrinsic activity of the catalyst. Compared to the unmodified CoCH/NF, the Fe,Mn-CoCH/NF exhibited significantly improved OER catalytic activity, characterized by a substantially reduced overpotential (204 mV at 10 mA cm −2 ) in alkaline electrolyte, alongside remarkable stability. Utilizing this catalyst, an overall water splitting (OWS) system was further developed, capable of driving efficient OWS at a low cell voltage (1.49 V at 10 mA cm −2 ). Furthermore, the unique hierarchical structure of Fe,Mn-CoCH/NF contributed to mitigating electrochemical corrosion and the toxic effects of Cl − during seawater electrolysis, enabling the catalyst to maintain excellent catalytic activity and stability even in alkaline seawater system.

Effect of Mg2+/F− co-doping on electrochemical performance of LiNi0.5Mn1.5O4 for 5 V lithium-ion batteries

Aijia Wei,Wen Li,Qian Chang,Xue Bai,Rui He,Lihui Zhang,Zhenfa Liu,Yanji Wang

Mg 2+ /F − co-doped LiNi 0.5 Mn 1.5 O 4 cathode material was synthesized by a facile one-step solid-state process. The effect of Mg 2+ /F − co-doping on grain morphology, phase structure, and electrochemical properties was studied by a series of characterizations. Scanning-electron-microscopy images show that Mg 2+ /F − co-doped LiNi 0.5 Mn 1.5 O 4 (denoted LNMO-MF) particles grow larger than pure LiNi 0.5 Mn 1.5 O 4 particles. X-ray diffraction, Raman spectra , Fourier transformation infrared spectroscopy , X-ray photoelectron spectroscopy, and cyclic-voltammetry tests indicate that all samples mainly display a Fd -3m space group and more Mn 3+ ions in the LNMO-MF sample after Mg 2+ /F − co-doping, which is conducive to increasing the cationic disorder degree and enhancing the electronic conductivity of electrode material. Results show that the LNMO-MF cathode material delivers an excellent rate performance with discharge capacities of 142, 144, 140 136, 132, 124, 115, and 100 mAh g −1  at 0.2, 0.5, 1, 2, 3, 5, 7, and 10C (1C = 140 mAh g −1 ), respectively. Remarkably, LNMO-MF also shows cycling stability with a capacity retention of 86.2% at 5C after 400 cycles, which is much higher than that of pure LiNi 0.5 Mn 1.5 O 4 (67.7%). The improvement of LNMO-MF's electrochemical properties could be ascribed to the Mg 2+ /F − co-doping, delivering a more stable structure, better crystallinity , the highest Li + diffusion coefficient , and the lowest charge-transfer resistance.

Mn–CoP/NC bifunctional catalysts with nanocube structures for alkaline water decomposition

Yuying Li,Shengxiong Liao,Yiming Gao,Dai Dang,Yuying Zheng,Fashen Chen

Developing highly efficient non-precious metal bifunctional catalysts remains a critical challenge in electrolytic water splitting research. In this study, we prepared Mn-doped CoP coupled with nitrogen-doped carbon nanocube (Mn–CoP/NC) catalysts using an in situ growth, low temperature oxidation, and phosphatization strategy. Due to the excellent activity of the cobalt species and the effective protection provided by the carbon shell to the metal core, these Mn–CoP/NC catalysts exhibited outstanding hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances. At a current density of 10 mA cm2, the overpotentials were as low as 90 mV for the HER and 272 mV for the OER. Moreover, the Mn–CoP/NC‖Mn–CoP/NC cell achieved a current density of 10 mA cm−2 at just 1.66 V and remained highly stable after 36 hours of continuous operation. This study offers a new strategy for designing efficient bifunctional catalysts for overall water splitting.

Enhanced Oxidation of Xylene Using Plasma Activation of an Mn/Al2O3 Catalyst

Zuliang Wu,Weili Zhou,Zhoubin Zhu,Xiaodong Hao,Xuming Zhang

Electric-field-modulated photoluminescence performance of Sm/Mn-codoped AgNbO3 antiferroelectric ceramics

Yihao Lin,Bingqing Yang,Cong Lin,Xiao Wu,Chunlin Zhao,Min Gao

The electric-field-modulated photoluminescence ( E -PL) performance of rare-earth-doped ferroelectric (FE) materials has been widely studied. However, the hysteresis effect in FE materials limits the tunability of E -PL modulation. Antiferroelectric (AFE) materials possess a reversible AFE-FE phase transition, inducing changes in crystal structure that can significantly affect the E -PL intensity. In this work, Sm/Mn-codoped silver niobate ceramics (ASMN x , x = 0, 0.5, 1, 1.5, 2) were fabricated via the tape-casting method, and the AFE properties, thermal stability, and E -PL performance were systematically investigated. The results show that the addition of Sm and Mn ions effectively inhibits the growth of grains and enhances the AFE properties. Upon irradiation at 480 nm, the samples exhibit a down-conversion PL effect, and the PL intensity increases with increasing Sm 3+ doping concentration. The in situ modulation of the PL intensity is reversibly achieved through the E -induced AFE-FE phase transition. Among them, ASMN1 shows the best tunability of −30.18% at 300 kV cm −1 . The excellent E -PL tunability in the lead-free ASMN x ceramics contributes to the broad applications in optical information storage, optical communication, and multifunctional optoelectronic devices.

Effect of zirconia crystal type on SCR activity of Mn/x-ZrO2

Changsheng Qu,Hao Zhou,Dongyao Xu,Jiaojiao Guo,Danyang Zhao,Xuewei Guo,Luyuan Xing

In this study, the manganese was loaded on three different zirconia crystal types by ultrasonic impregnation method, and the performance of selective catalytic reduction (SCR) of NOx with NH3 was tested. The characteristics of the catalytic were tested by BET, XRD, SEM, and XPS. It was founded that the performances of unloaded different crystal zirconia was basically the same which were less than 40%. Compared with unloaded catalyst, the DeNOx performance of catalysts after loaded manganese was greatly improved, and the crystal type had obvious influence on the DeNOx performance of Mn/x-ZrO2. The Mn/m-ZrO2 had the highest DeNOx performance (90.97% at 240 °C) compared with the Mn/t-ZrO2 and Mn/c-ZrO2. The difference of crystal type made Mn/m-ZrO2 have lower surface Mn average valence states and more oxygen vacancy, which made it have best DeNOx performance. The effects of SO2, H2O, and alkali metal on DeNOx efficiency were also tested.

Microdefects evolution and electrochemical performance modulation of Mn doped VO2(B) nanorods

Dewei Liu,Qijie Zhang,Saipeng Ding,Fufeng Yan,Haiyang Dai,Tao Li,Renzhong Xue,Jing Chen,Gaoshang Gong,Cui Shang,Xuezhen Zhai

A series of nano-V 1- x Mn x O 2 samples ( x = 0–0.035) were prepared by a simple solvothermal method. XRD patterns and the Rietveld refinement results of V 1- x Mn x O 2 samples showed that Mn ions were incorporated into the V sites during the solvothermal process. XPS results indicated that the valence state of Mn ion was a mixed state of Mn 2+ , Mn 3+ and Mn 4+ . The corresponding relationship between the diameter, specific surface area and electrochemical performances of V 1- x Mn x O 2 nanorods was studied. It can be found that Mn doping promoted the insertion of K + ions into the electrode material and improved the conductivity, discharge capacity and cycle stability, which was due to more defects induced by Mn doping. The x  = 0.020 sample had the largest specific capacitance (the 88% capacity retention rate after 550 cycles at 0.1 A·g −1 ) due to the improvement of structural stability by Mn-ion doping. These results provide great potential applications for nano-VO 2 (B) in the cathode material of lithium-ion battery and supercapacitor .

Zero Voltage-Degradation of Li2MnO3 with Ultrathin Amorphous Li─Mn─O Coating

Shiqi Liu,Jie Wan,Boya Wang,Chenghan Li,Yulong Wang,Lin Wang,Haipeng Wu,Nian Zhang,Xu Zhang,Haijun Yu

Manganese-based lithium-rich layered oxides (Mn-LLOs) are promising candidate cathode materials for lithium-ion batteries, however, the severe voltage decay during cycling is the most concern for their practical applications. Herein, an Mn-based composite nanostructure constructed Li 2 MnO 3 (LMO@Li 2 MnO 3 ) is developed via an ultrathin amorphous functional oxide Li x MnO y coating at the grain surface. Due to the thin and universal LMO amorphous surface layer etched from the lithiation process by the high-concentration alkaline solution, the structural and interfacial stability of Li 2 MnO 3 are enhanced apparently, showing the significantly improved voltage maintenance, cycle stability, and energy density. In particular, the LMO@Li 2 MnO 3 cathode exhibits zero voltage decay over 200 cycles. Combining with ex situ spectroscopic and microscopic techniques, the Mn 2+/4+ coexisted behavior of the amorphous LMO is revealed, which enables the stable electrochemistry of Li 2 MnO 3 . This work provides new possible routes for suppressing the voltage decay of Mn-LLOs by modifying with the composite functional unit construction.

Enhancing Mn Emission of CsPbCl3 Perovskite Nanocrystals via Incorporation of Rubidium Ions

Jian Yang,Xi Yuan,Lin Fan,Yuzhu Zheng,Fanshu Ma,Haibo Li,Jialong Zhao,Huilian Liu

Mn doped cesium lead halide perovskite nanocrystals (NCs) have potential application for white light emitting diodes. However, the emission of doped NCs is limited to trap-mediated energy transfer. The Mn doped CsPbCl 3 NCs with corporation of rubidium (Rb + ) ions (Mn:Cs 1-x Rb x PbCl 3 NCs, x = 0, 0.1, 0.2, 0.3, and 0.4) were synthesized. The effect of the optical and structural properties of Mn:Cs 1-x Rb x PbCl 3 NCs were studied by steady-state and time-resolved photoluminescence spectroscopy. The photoluminescence quantum yields and lifetimes of Mn doped CsPbCl 3 NCs with different Rb + contents were obtained. It was found that the Mn doped CsPbCl 3 NCs with Rb + content of 0.1 exhibited the highest Mn 2+ emission quantum yield up to 63.18%. Interestingly, the temperature-dependent PL spectra demonstrated the enhanced Mn 2+ emission of Mn doped CsPbCl 3 NCs at low temperature of 80 K. The experimental result indicated the Mn 2+ emission of Mn doped CsPbCl 3 NCs was enhanced by incorporating Rb + ions.

Unveiling Dopant-Induced Ultrafast Exciton Dynamics in Mn/Yb Codoped Perovskite Nanocrystals

Weifan Niu,Ruidan Zhang,Zhibin Wang,Feng Huang,Daqin Chen

Perovskite nanocrystals (NCs) with intentionally introduced Mn 2+ /Yb 3+ activators enable tunable emissions covering UV-orange-NIR spectral range. However, the exact microscopic energy transfer mechanisms in this system remain unknown. Herein, Mn/Yb codoped CsPbCl 3 perovskite NCs with triple emissions originated from exciton recombination of host, 3d–3d transition of Mn 2+ and 4f–4f transition of Yb 3+ are prepared. Femtosecond resolution transient absorption spectra performed on the pristine CsPbCl 3 , Mn-doped, Yb-doped and Mn/Yb codoped samples clarify efficient and simultaneous energy transfer (ET) from excitons to Mn 2+ and Yb 3+ dopants. It is testified the sensitizations of dopants mainly result from the trapped hole, taking 285 ps for Mn 2+ and 17 ps for Yb 3+ respectively, which make less trapped hole recombine with de-localized carriers. Importantly, energy transfer processes from host to Mn 2+ and Yb 3+ activators emerge as competition, and the ET probability of exciton-to-Mn 2+ is higher than that of exciton-to-Yb 3+ . Finally, control experiments further prove that tunable Mn 2+ orange emission and Yb 3+ NIR emission are achievable via elaborate adjustment of the dopant concentrations.

Pyridine-Modulated Mn Ion Emission Properties of C10H12N2MnBr4 and C5H6NMnBr3 Single Crystals

Xianwei Bai,Haizheng Zhong,Bingkun Chen,Cheng Chen,Junbo Han,Ruosheng Zeng,Bingsuo Zou

Pb-free inorganic–organic perovskite materials - C10H12N2MnBr4 (compound 1) and C5H6NMnBr3 (compound 2) - with different structures were obtained by using pyridine and manganese bromide as raw materials. The single-crystal X-ray diffraction analyses revealed their different lattices in space groups. Compound 1 - Mn tetra-Br-coordinated with two pyridines - presented an isolated mononuclear structure. Its temperature-dependent photoluminescence spectra exhibited an emission band at 523 nm from the lowest d–d crystal field transition of Mn and a higher energy emission at 493 nm from its vibronic state at low temperature. Compound 2 - Mn octahedra-Br-coordinated with a minor pyridine - face-shares with linear chains, which were separated by pyridine molecules. Its emission peak occurred at around 650 nm, in which ferromagnetism was observed. The lifetimes of d–d transition for a single manganese ion and the Mn cluster were presented.