Materials Today Communications
·
2023
·
IF 3.8
Yusheng Yang,Bai Sun,Guangdong Zhou,Chuan Ke,Jie Zhang,Yongzan Zhou,Shuangsuo Mao,Jiajia Qin,Yong Zhao
Since memristors have shown great application prospects in non-volatile memory, neural synapse, brain-like chips, artificial intelligence (AI) and quantum computers, the research of memristors has received extensive attention. In this work, the resistive switching (RS) device with Ag/SrTiO 3 (STO)/Ti structure was fabricated, and it can significantly improve the RS performance of device by doping Mn ions into STO to replace part of Ti ions . That is to say, the Ag/Mn-doped SrTiO 3 (SMTO)/Ti device exhibits larger resistance window and better retention at room temperature. Finally, through in-depth mechanistic analysis, a physical model of the conducting filament and Schottky emission was established to understand the charge transport mechanism and RS behavior of the device. In particular, it provides favorable factors for the migration of ions and electrons through the Mn doping because the substitution of Mn for Ti ions reduces the volume of the STO crystal while distorting its crystal shape since the ionic radius of Mn is smaller than that of Ti. This work provides an important way to improve the RS properties of ABO 3 -type perovskite-based resistive random access memory (RRAM), and helps to explore the cutting-edge applications of high-performance RS devices in information processing and AI.
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Results in Physics
·
2023
·
IF 5.3
Jin Qiu,Wen-Juan Huang,Young Jin Lee,Seung Kim,Xiang-Bai Chen,In-Sang Yang
Magnetism in van der Waals (vdW) materials has recently garnered significant attention due to their potential for advanced applications. In this study, we investigate the magnetic transition in layered MPSe 3 (M = Fe, Mn) bulk flakes utilizing temperature-dependent Raman spectroscopy. Our findings reveal unique features in the Raman spectrum that are strongly correlated with the antiferromagnetic ordering in MPSe 3 . We analyze the spin-dependent Raman scattering modes in MPSe 3 by applying the Suzuki–Kamimura formalism. Consequently, our comparative analyses of the spin correlation function and the reduced magnetization provide compelling evidence of the 2D Ising characteristic especially in FePSe 3 . Our results clearly show the potential of MPSe 3 as a prominent platform for exploring fundamental aspects of low-dimensional magnetism.
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CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Fuming Miao,Shuai Zhang,Xueliang Sun,Yamin Li,Ruize Shang,Wenli Wu,Weizhou Jiao,Youzhi Liu
In this study, Mn-CoO X / γ -Al 2 O 3 (MCA) was prepared by impregnation for catalytic ozonation of phenol in a rotating packed bed (RPB), and the effects of high gravity factor ( β ), liquid flow rate ( Q L ), initial solution pH and gaseous ozone concentration ( C O 3 ) on the mineralization of phenol were explored. The results show that the degradation rate of phenol ( η phenol ) reaches 100% at 9 min and the mineralization rate ( η TOC ) reaches 95.01% at 45 min under conditions of β = 104, C O 3 = 80 mg L -1 , Q L = 80 L/h, and pH = 6. Compared with the bubbling reactor (BR)/MCA/O 3 and O 3 /RPB systems, the η TOC of the MCA/O 3 /RPB system is increased by 25.81% and 40.85%, respectively. The electron paramagnetic resonance (EPR) results reveal that hydroxyl radical (·OH) plays a critical role in the degradation of phenol by MCA catalyzed ozonation. The quenching experiment using tertiary butyl alcohol (TBA) as a scavenger of ·OH reveals that the ratio of direct and indirect degradation of phenol is 16:9. The intermediates generated during the degradation of phenol were detected by gas chromatography-mass spectrometry (GC–MS), and possible degradation pathways were proposed. In conclusion, MCA-catalyzed ozonation and RPB have a synergistic effect on ·OH initiation and improve the degradation and mineralization of phenol. This study provides a new perspective for the degradation of phenol.
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Catalysts
·
2023
·Vol. 13
·期 7
·1031
·
IF 3.9
Jie Lin,Yihong Ding,Huile Jin,Tianbiao Zeng
Nickel, cobalt, and manganese oxides are easily obtainable non-noble metal catalysts for water splitting. However, the relationship between composition and catalysts’ performance still needs systematic studies. Herein, guided by theoretical calculations, a low overpotential, easily prepared Mn-doped Co3O4was deposited on graphite plates for water splitting. The 30% Mn-doped Co3O4(Co2.1Mn0.9O4) required the lowest overpotential for oxygen evolution reaction (OER), in which the Co2.1Mn0.9O4reached 20, 30, and 50 mA cm−2in the overpotentials of 425, 451, and 487 mV, respectively, with 90% IR compensation. Under overall water-splitting conditions, the current density reached 30 mA cm−2at an overpotential of 0.78 V without IR compensation. Charge density difference analysis illustrates that doped Mn provides electrons for O atoms, and that Mn doping also promotes the electron fluctuation of Co atoms. XPS analysis reveals that Mn-doping increases the chemical valence of the Co atom, and that the doped Mn atom also exhibits higher chemical valence than the Mn of Mn3O4, which is advantageous to boost the form of based-OOH* radical, then decrease the overpotential. Considering the particular simplicity of growing the Co2.1Mn0.9O4on graphite plates, this work is expected to provide a feasible way to develop the high-performance Co-Mn bimetallic oxide for water splitting.Keywords:water splitting;bimetallic oxides;Mn-doped Co3O4;DFT calculation
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WATER RESEARCH
·
2022
·
IF 13.4
Zheng-Yu Dong,Yi-Li Lin,Tian-Yang Zhang,Chen-Yan Hu,Yang Pan,Renjie Pan,Yu-Lin Tang,Bin Xu,Nai-Yun Gao
To improve the performance of the conventional coagulation process, a permanganate (Mn(VII)) pre-oxidation combined with Fe(III)/peroxymonosulfate (PMS) coagulation process (Mn(VII)-Fe(III)/PMS) that can significantly improve the removal of dissolved organic carbon (DOC), turbidity, and micropollutants is proposed in this study. Compared with conventional Fe(III) coagulation, the Mn(VII)-Fe(III)/PMS process can also significantly enhance the removal of iohexol and sulfamethoxazole in raw water. During this process, the primary reduction product, Mn(IV), after Mn(VII) pre-oxidation was adsorbed on the floc surfaces and involved in the Fe(III)/PMS process. The natural organic matter (NOM) in raw water mediated the redox cycle of iron. The synergistic effect of NOM, Fe, and Mn facilitated the redox cycle of Mn(III)/Mn(IV) and Fe(III)/Fe(II) to promote the activation of PMS. The sulfate radical (SO 4 •− ) played an important role in the degradation of micropollutants. The formation potential of the detected volatile disinfection by-product (DBP) during the subsequent chlorination was reduced by 21.9% after the Mn(VII)-Fe(III)/PMS process. This study demonstrated the promising application of the Mn(VII)-Fe(III)/PMS process for coagulation and micropollutant control and illustrated the reaction mechanism. This study provides guidance for improving conventional drinking water treatment processes.
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PubMed
高影响因子
WATER ENVIRONMENT RESEARCH
·
2022
·Vol. 94
·期 9
·e10788
·
IF 3.306
Binbin Shao,Yating Zhu,Jie Chen,Yimin Lin,Xiaohong Guan
During oxidative treatment of iodide (I − )-containing waters, I − is easy to be oxidized into hypoiodous acid (HOI) by various oxidants and the further reaction of HOI with organic compounds can lead to the formation of iodinated disinfection by-products (I-DBPs). Oxidation of HOI to iodate (IO 3 − ) or reduction of HOI to I − has been proposed to reduce the formation of I-DBPs. Because the reaction of HOI with sulfite proceeds rapidly, this study examined the fate of iodine and the formation of I-DBPs in Mn(VII)/sulfite process. Results showed that I − was oxidized to HOI but the further formation of IO 3 − was suppressed due to the fast reduction of HOI to I − by sulfite. The reactions of HOI with SO 3 2− and IO − with SO 3 2− are the major pathways with species-specific second-order rate constants determined to be 1.12 × 10 5 M −1 s −1 and 9.43 × 10 7 M −1 s −1 , respectively. The rapid reaction of HOI with sulfite plays an essential role in minimizing the formation of iodinated products in HOI- and phenol-containing solutions. The toxic risk analysis showed that the toxicity of the generated DBPs from Mn(VII)/sulfite pre-oxidation followed by chlorination only changed slightly. Practitioner Points The decay of I − was negligible in Mn(VII)/sulfite process. The rapid reaction of HOI with SO 3 2− resulted in the negligible generation of IO 3 − . Mn(VII)/sulfite process exerted slight influence on the formation of I-DBPs. Mn(VII)/sulfite process is promising for the pretreatment of I − -containing water.
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高影响因子
Journal of Physical Chemistry C
·
2022
·
IF 4.177
Shuaigang Ge,Wenyong Jia,Bao Ke,Qilin Wei,Chengzhi Yang,Shangfei Yao,Hualin Zhao,Zi-An Li,Xianci Zhong,Bingsuo Zou
All-inorganic metal halide perovskite semiconductors have great potentials in lighting applications, but the effect of excitonic magnetic polarons (EMPs) in the transition metal (TM) ion-doped halide perovskites on their luminescence processes has not been extensively understood. Here, we have synthesized Mn2+-doped Rb3Cd2Cl7 perovskite powders with different doping amounts by a hydrothermal method. After Mn(II) is doped, Rb3Cd2Cl7 gives strong emission, though the Rb3Cd2Cl7 powder itself does not emit light. This emission originates from the intrinsic self-trapped exciton (STE) formation enhanced by the ferromagnetic Mn–Mn pair with spin–spin coupling, that is, the magnetic polaron whose astonishing luminescence at 587 nm has a quantum yield up to 147%. Some shallow trapped centers below the conduction band out of high d levels by localized EMPs after photoexcitation are proven to add to this luminescence process. The thermoluminescence phenomenon with rising temperature proves that these shallow trapped carriers are present with phonon and multiphonon notation, and their efficient transfer to the conduction band and the STE state occurs via the electron–phonon coupling during photoexcitation. This compound provides a new way for TM-doped perovskite material design and applications for magneto-optical and display technology.
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ENVIRONMENTAL ENGINEERING SCIENCE
·
2022
·Vol. 39
·期 3
·259-267
·
IF 2.172
Yue Sun,Lijiang Tian,Bingkun Liu,Fulong Chen,Sijie Ge
In this article, Mn/I-TiO2 nanocatalyst was prepared by sol-gel method and used as the photocatalyst to discompose the gaseous benzene in the visible light. The crystal phase composition and grain size of the photocatalyst were investigated by X-ray diffraction and Raman, respectively. X-ray photoelectron spectroscopy and ultraviolet-visible diffuse reflectance spectroscope were used to study the surface elements and bandgap width of the photocatalyst. The research findings suggested that the crystal type of all catalysts was anatase. TiO2 nanoparticle doped by Mn/I could reduce its crystallite size and augment lattice distortion because of the formation of oxygen vacancies. The generation rate, migration rate, and disintegration rate of electron-hole pairs were increased by modification of TiO2. Meanwhile, the Mn-TiO2 was recognized with the smallest bandgap among four kinds of catalyst. Mn-TiO2 catalyst exhibited the highest efficiency on gaseous benzene removal (37.86%) among pure-TiO2 (3.33%), I-TiO2 (30.21%), and Mn-I-TiO2 (31.56%) under visible light. Correspondingly, the photocatalytic ability of pure-TiO2, I-TiO2, Mn-I-TiO2, and Mn-TiO2 was 51.25 μg C6H6/(g·h), 424.36 μg C6H6/(g·h), 493.61 μg C6H6/(g·h), and 245.43 μg C6H6/(g·h), respectively.
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JOURNAL OF CHEMICAL SCIENCES
·
2022
·Vol. 134
·期 2
·1-11
·
IF 2.15
Yu Miao,Ji Shuai,Li Zhifang,Song Kun,Li Yueyu,Yang Jian,Yang Changlong
A simple ion-exchange method is used to prepare Mn and Co-supported TNU-9 denitration catalyst for NH 3 -SCR. The denitration activity and H 2 O/SO 2 resistance performance of the catalyst are systematically studied. The denitration activity test exhibits that the NO x removal rate of Mn-Co/TNU-9 is higher than that of Mn/TNU-9 and Co/TNU-9, the NO x removal rate is greater than 90% and the N 2 selectivity is greater than 99% in the range of 150 ~ 450 °C. It is because the redox cycle of Mn 4+ + Co 2+ ↔ Mn 3+ + Co 3+ improves the redox performance of the catalyst, which is conducive to the conduction of electrons, and then accelerates the oxidation of NO to NO 2 to produce a "fast SCR" reaction, and finally optimizes the overall SCR performance. Furthermore, the change is not significant for the catalytic activity over Mn-Co/TNU-9 in the presence of water. However, the sulfur resistance is poor at low temperatures due to the presence of ammonium bisulfate. It also has excellent catalytic stability. Therefore, supported TNU-9 catalysts will have a good development prospect in denitrification. Graphical abstract Mn-Co co-doped TNU-9 catalyst was successfully synthesized by simple ion exchange method and applied in the NH 3 -SCR. The results show that Mn-Co/TNU-9 catalyst has an excellent wide activity window in a wide temperature range of 150-450°C (NO x conversion over 90%), which is because Mn+Co 2+ ↔Mn+Co improves the redox performance and facilitates the electron transfer, which further accelerates the oxidation of NO into NO 2 that could result in the “Fast SCR” reaction. The synergistic effect between Mn and Co bimetallic can also improve activity. Moreover, Mn-Co/TNU-9 has very good catalytic stability.
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高影响因子
MICROCHEMICAL JOURNAL
·
2022
·
IF 5.304
Wenhao Peng,Ningning Song,Zilong Su,Jiajun Wang,Kaixuan Chen,Shuji Li,Bingyan Wei,Shiping Luo,Aijuan Xie
A series of MoS 2 and Mn metal organic frameworks (Mn-MOF) were synthesized by hydrothermal method, and then MoS 2 , Mn-MOF and multi-walled carbon nanotubes (MWCNT) were mixed in different mass ratios and applied for supercapacitor. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge (GCD) are used to investigate the electrochemical performance of MoS 2 /Mn-MOF/MWCNT materials with different mass ratios. The experimental results show that when the mass ratio of m(MoS 2 ): m(Mn-MOF): m(MWCNT) is 1:4:1, the electrochemical performance of the MoS 2 /Mn-MOF/MWCNT composite is the best. The specific capacitance of optimal MoS 2 /Mn-MOF/MWCNT (1:4:1) reaches 862.73F g −1 , which is noticeable higher than that of MoS 2 (42.29F g −1 ), Mn-MOF (70.23F g −1 ) and MWCNT (347.27F g −1 ) materials. Moreover, the EIS test manifests that the MoS 2 /Mn-MOF/MWCNT (1:4:1) composite has a lower R ct value (2.566 Ω). Therefore, MoS 2 /Mn-MOF/MWCNT (1:4:1) has the best electrochemical performance among the all as-fabricated supercapacitor materials. This research provides an effective method for the development of Mn-based supercapacitor materials and improves the capacitance performance of MOFs materials.
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Nano Energy
·
2021
·
IF 17.881
Tao Huang,Hui Peng,Qilin Wei,Chengyu Peng,Ye Tian,Shangfei Yao,Xinxin Han,Bingsuo Zou
If we introduce transition metal ions with spins into an organic-inorganic halide perovskite compounds, interesting spin dependent optical properties may be seen in this system. This paper reports an organic-inorganic hybrid manganese ion doped lead halide crystal incorporated by TDMP (trans-2,5-dimethylpiperazinium), it gives not only the STE1 (polaronic exciton), usually brought up by the enhanced electron-phonon coupling in the amine incorporated compound, but also give a novel bipolaronic exciton (STE2) for the paired charge state formation due to the incorporation of bi-amine cationic molecules, a excitation by the polaronic molecule due to enhanced electron-phonon coupling and neighboring correlation out of the Mn ion ferromagnetic spin coupling in the lattice at slightly high doping. Such magnetic bipolaron state could often be accompanied by several multiphonon Raman modes and ferromagnetism. It is even interesting that this state can give super-high red emission with PLQY at ~92.5% at room temperature. Moreover, the emission color and intensity could also be modulated by the Mn doping concentration, temperature, and laser excitation power. The low doping products can give green emission out of single Mn d-d transition at very low temperature or high laser excitation power. The intermediately doped products can give white emission out of STE1 and STE2. The highly doping products give red emission out of STE2 (bipolaron states) at room temperature or low laser power. These interesting phenomena reflected the microscopic interactions between spins, carriers and phonons in the products, which can be found applications in the future fields of photonics and spintronics.
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ChemistrySelect
·
2023
·Vol. 8
·期 18
·e202204645
·
IF 2.1
Yingzi Huang,Xue Ye,Xinhua Gao,Lisheng Guo,Yaqiong Wang,Wenlin Xu,Jie Li
Graphical A hollow microcage structured CoMn- x catalyst was synthesized by the template method. In which abundant CO 3+ as well as surface reactive oxygen species on the surface of the CoMn-2 catalyst enabled it to exhibit extremely high catalytic activity for CO under space velocity 36,000 mL g cat −1 h −1 , being able to completely eliminate CO at 80 °C and maintain stable catalytic activity for up to 100 h. Cost-effective and highly efficient catalyst is a promising way for the removal of CO in automotive exhaust purification. Herein, a series of novel self-assembled CoMn bimetallic catalysts with hollow microcage structure have been prepared through zeolitic imidazole framework (ZIF-67) assisted method followed by direct pyrolysis in static air. Both the Mn loading and the unique hollow microcage structure play important roles in CO low-temperature oxidation, and the highest catalytic activity is obtained for CoMn-2 catalyst, which presents T 100 (temperature of 100 % CO conversion) at 80 °C. Through a systematic series of experiments, we further demonstrate that our catalysts’ superior catalytic performance arises from small particle size, high surface active oxygen content and Co 3+ /(Co 2+ +Co 3+ ) ratio. Such configuration of catalysts will pave the way for new strategies to design noble-free high-performance catalysts for CO low-temperature oxidation.
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