ENVIRONMENTAL POLLUTION
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2022
·
IF 9.988
Zhuozhi Ouyang,Fadan Lei,Endian Hu,Shuxing Li,Qian Yao,Xuetao Guo
Tetracycline (TC) and Mn(II) is a common antibiotic and metal ion respectively. Nevertheless, literatures involving in the effects of Mn(II) on TC transformation are still insufficient. In this study, the kinetic experiment, spectral analysis, complexation experiment and electrochemical analysis, theoretical calculation and products detection were carried out to probe into oxidation and photolysis of TC with Mn(II). Mn(II) greatly accelerated TC oxidation, preferably tending to complex with TC at O10 – O12 or O2 – O3 site. There were a TC-Mn(II)/TC-Mn(III) redox couple and electron transfer process. Conversely, Mn(II) inhibited photolysis of TC. The photolysis of excited TC could compete with energy dissipation reactions. The electron transfer and complexation reaction easily made excited TC energy transfer, thus slowing down photolysis process. During the TC transformation, the intensity of functional groups was significantly decreased. Simultaneously, the degradation pathways mainly included eight reactions. It is a very interesting and probably overlooked phenomenon, which identifies new transformation of TC with Mn(II). This study helps to further understand fate and environmental behavior of antibiotics and metal ion .
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Catalysis Science & Technology
·
2022
·Vol. 12
·期 8
·2426-2437
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IF 6.177
Xinxin Zhang,Jiajun Dai,Jiageng Ding,Kok Bing Tan,Guowu Zhan,Jiale Huang,Qingbiao Li
Direct epoxidation of propylene (DEP) to propylene oxide (PO) with molecular oxygen is a very desirable reaction but remains a challenge due to the absence of efficient catalysts with high selectivity. The catalytic performance for direct epoxidation of propylene is well related to surface adsorbed electrophilic oxygen species. Herein, we prepared a series of Mn-doped La2CuO4 perovskites (LaMnxCu1−xO3) with adjustable valence electronic structure as selective catalysts to explore the impacts of catalyst intrinsic electronic structure evolution on the activation of molecular oxygen. Therein, LaMn0.5Cu0.5O3 performed the best with a PO selectivity of 74.2% at 150 °C. The characterization results and DFT calculations revealed that the excellent catalytic performance of LaMn0.5Cu0.5O3 might be ascribed to the change of molecular oxygen activation sites: from oxygen vacancy active sites on La2CuO4 to Cu active sites on LaMn0.5Cu0.5O3. Meanwhile, there was a synergistic interaction between manganese and copper affecting the electron density on Cu sites and ultimately modulating the activated states of surface adsorbed oxygen species. In addition, we employed crystal band theory to associate the oxygen vacancy density with the Cu valence state. This is important for people to understand the bulk electronic structure evolution rules caused by transition metal doping and to design catalysts efficiently for oxygen-based chemical reactions.
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Journal of Physical Chemistry C
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2022
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IF 4.177
Zhaoxia Yang,Wenming Tian,Fengke Sun,Shengye Jin,Dongjiang You
One-dimensional (1D) perovskites are ideal broadband-emitting phosphors for white-emitting diode applications. Doping Mn2+ in 1D perovskites provides a new idea to tune the materials’ light-emitting properties. Here, we report an excitation-power-dependent dual-band emission from both self-trapped excitons (STEs) and Mn dopants in individual 1D Mn-doped DMEDAPbBr4 single crystals. By changing the excitation intensity, we realize a broad and continuous color tuning range between blue and orange. The temperature-dependent photoluminescence (PL) and transient spectroscopy measurements demonstrate that the tunable emission color is enabled by the competitive transfers of excitons to the STE state and Mn2+ ions. The Mn-doped 1D perovskites exhibit a high photostability by showing a continuous switch between blue and orange emissions during an uninterrupted operation time of 7.5 h. The high stability and emission-color switchable properties make the Mn-doped 1D perovskites special optically tunable PL materials for potential light-emitting applications.
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International Journal of Environmental Research and Public Health
·
2022
·Vol. 19
·期 15
·9437
·
IF 4.614
Qianli Guo,Xianhu Qi,Jian Zhang,Bo Sun
Aqueous complexes of Mn(III) ion with ligands exist in various aquatic systems and many stages of water treatment works, while HSO3−is a common reductant in water treatment. This study discloses that their encounter results in a process that oxidizes organic contaminants rapidly. Pyrophosphate (PP, a nonredox active ligand) was used to prepare the Mn(III) solution. An approximate 71% removal of carbamazepine (CBZ) was achieved by the Mn(III)/HSO3−process at pH 7.0 within 20 s, while negligible CBZ was degraded by Mn(III) or HSO3−alone. The reactive species responsible for pollutant abatement in the Mn(III)/HSO3−process were SO4•−and HO•. The treatment efficiency of the Mn(III)/HSO3−process is highly related to the dosage of HSO3−because HSO3−acted as both the radical scavenger and precursor. The reaction of Mn(III) with HSO3−follows second-order reaction kinetics and the second-order rate constants ranged from 7.5 × 103to 17 M−1s−1under the reaction conditions of this study, suggesting that the Mn(III)/HSO3−process is an effective process for producing SO4•−. The pH and PP:Mn(III) ratio affect the reactivity of Mn(III) towards HSO3−. The water background constituents, such as Cl−and dissolved organic matter, induce considerable loss of the treatment efficiency in different ways.Keywords:Mn(III);bisulfite;advanced oxidation processes;sulfate radical;micropollutant abatement
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ENVIRONMENTAL RESEARCH
·
2022
·
IF 8.431
Yajie Guo,Xinyu Zhang,Dandan Zhang,Shunlin Li,Hui Wang,Yiyin Peng,Zhaoyong Bian
The present work demonstrates a simple one-step pyrolysis method for the synthesis of a catalytic sludge-based carbon (SBC) biochar containing Fe and Mn from dehydrated sludge with added KMnO 4 and Fe(II). The electrocatalytic degradation of triclosan (TCS) in water was evaluated using an Fe/Mn-SBC cathode to promote a heterogeneous Fenton-like reaction. The catalyst generated at 500 °C exhibited an abundant porous structure and a relatively high surface area, and produced an electrode with better conductivity and electron diffusion . The presence of metal oxides changed the surface structure defects of this biochar and enhanced its catalytic performance while increasing the electrochemically active surface area by 72.68 mF/cm 2 compared with plain SBC. TCS was degraded (91.3%) within 180 min by oxygen species generated in situ on an Fe/Mn-SBC cathode because the activation energy for oxygen reduction was lowered by 4.62 kJ/mol. The degradation of TCS followed pseudo first-order kinetics and was controlled by TCS diffusion and interfacial chemical reactions between adsorbed TCS and the electrode. Possible TCS degradation pathways were devised based on the main intermediates, and 1 O 2 was found to be more important than •OH radicals. Through toxicity test and prediction, the toxicity of degradation was gradually reduced. This study demonstrates a simple and ecofriendly method for the electrocatalytic degradation of organic pollutants.
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ACS Applied Materials & Interfaces
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2022
·
IF 10.383
Yuming Xi,Yangcheng Lu
In this work, for the performance enhancement of iron hexacyanoferrate, an electrochemically active Mn-doped iron hexacyanoferrate cathode is fabricated via a bottom-up approach. It is found that the pre-treatment of interstitial water and appropriate Mn doping are two keys to achieving higher capacity and higher stability. The interstitial water has a trade-off effect between the alleviation of volume expansion upon Na+ (de)intercalation and the retardation of Na-ion diffusion. The moisture-tailored iron hexacyanoferrate with appropriate Mn doping exhibits a high initial Coulombic efficiency of 94.8%, enhanced capacity and rate performance, and excellent cycling stability. These results benefit from the fact that the extraction/insertion of Na ions from/into the lattice via a solid-solution mechanism correspond to both the slight volume expansion and fast sodium diffusion rate; otherwise, the removal of interstitial water and a higher Mn content might lead to poor cycling stability due to excessive volume expansion resulting from rhombohedral to cubic phase transformation. Finally, the less demand on the control of air humidity for the fabrication of electrodes and the potential for the full cell coupled with hard carbon are also demonstrated, which shows great potential for practical applications.
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Sustainable Chemistry and Pharmacy
·
2022
·
IF 5.464
Zhenwei Zhang,Xiaoshi Ma,Chuanjun Yue,Xuejiao Wei,Baoliang Liu,Xiaohui Chen
Hazardous waste alkaline batteries and waste fatty acids significantly threaten the environment. In this study, waste alkaline batteries were simply transferred to r-MnZn catalysts, which were then applied in the ketonization of fatty acids. The assessment results show that r-MnZn can efficiently convert n-octanoic acid to 8-pentadecanone. The conversion and yield are evaluated as 100% and 92.9%, respectively, which are much better than those of TiO 2 , ZrO 2 , CeO 2 and other metal oxides . The excellent catalytic efficiency is derived from the MnO 2 nanorods in r-MnZn materials which are characterized by XRD, TEM, and XPS. In addition, when using different kinds of fatty acids in ketonization, longer carbon chains require a higher activation energy, and the conversion of fatty acids was lower. Furthermore, the ketone products have a short carbon chain that induces side reactions, leading to a low yield. The above results indicate that r-MnZn is an efficient catalyst applied in the ketonization of fatty acids.
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NANOTECHNOLOGY
·
2022
·Vol. 33
·期 45
·455703
·
IF 3.953
Lei Wang,Hengbin Mao,Junhui Li,Yi Li,Mingliang Li,Jinpeng Zhu,Bingbing Fan,Wen Liu,Gang Shao,Hongliang Xu,Hailong Wang,Rui Zhang,Hongxia Lu
CsPbX3 (X = Cl, Br, I) semiconductor nanocrystals (NCs) have excellent optical and photoelectric properties, and are potential core materials for various photoelectric devices. However, the toxicity of Pb and instability have been the key limitations to application of NCs. Herein, using MnBr2 and MnBr2·4H2O as manganese sources, heavy Mn-doped CsPbBr3 (Mn:CsPbBr3) NCs are synthesized by high-energy ball grinding, which avoids high temperature, a large number of polar solvents and atmosphere protection required in traditional liquid phase methods. However, when MnBr2·4H2O is used as the raw material, infinite solid solution doping can be achieved, and the synthesized Mn:CsPbBr3 NCs show smaller particle size, stronger PL intensity and stability. The reason is that presence of crystal water plays a similar role to wet milling in the ball milling process, and can promote the passivation effect of oleylamine (OAm) on nanocrystal defects and the connection between them. In addition, a simple, easy-operating and beneficial to commercial production method for the preparation of Mn:CsPbBr3 NCs/EVA flexible films is proposed, which can effectively improve the stability of Mn:CsPbBr3 NCs. This study is expected to provide an effective way for the synthesis and stability improvement of CsPbX3 NCs doped with different ions.
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SENSORS AND ACTUATORS B-CHEMICAL
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2021
·
IF 7.46
Cong Qin,Bing Wang,Yingde Wang
Improving the gas-sensing performances of p-type oxide semiconductors is an important research issue. Here, we reported the simple fabrication of bare Co 3 O 4 and Mn-doped Co 3 O 4 porous nanosheets by annealing the Co-based metal-organic frameworks (MOFs) nanosheets precursors synthesized from the ion-assisted solvothermal treatment. Different characterization techniques were adopted to verify the physical and chemical morphologies of the as-prepared samples. The results demonstrate that Mn cations have been successfully doped into the lattice of Co 3 O 4 . Besides, these prepared samples were used for detection of carbon monoxide (CO). Results show that 3 mol% Mn-doped Co 3 O 4 nanosheets present enhanced CO-sensing properties [(R g − R a )/R a = 280% to 40 ppm at 125 °C] compared with bare Co 3 O 4 nanosheets. The response reported here for the detection of CO even exceeds those of some n-type oxides under the same conditions. We speculate that the enhanced CO-sensing properties are probably due to the high specific surface area, abundant oxygen vacancies generated by Mn doping, and the relatively high Co 3+ /Co 2+ ratio. The Mn-doped Co 3 O 4 sensor has a huge potential advantage in detecting low concentrations of CO.
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JOURNAL OF MATERIALS SCIENCE
·
2021
·Vol. 56
·期 34
·19155-19164
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IF 4.22
Fan Xuhui,Wang Jing,Rao Yu,Zhao Lei,Zhu Kongjun
Dielectric ceramics have attracted ever-increasing interest in energy storage applications due to their high-power density and fast charge–discharge speed. In particular, AgNbO 3 -based antiferroelectric ceramics are considered potential substitutes for lead-based ceramics. AgNbO 3 ceramics sintered with fine hydrothermal-synthesized powders show the advantage of high breakdown strength. However, the fine grains lead to the decreased polarization, which harms the recoverable energy density. In this work, a little amount over-stoichiometrical WO 3 and MnO 2 were introduced to synergistically improve the polarization and dielectric breakdown strength of obtained AgNbO 3 ceramics. The dependences of structures and dielectric properties on WO 3 doping were explored. A maximum polarization of 49.4 μC/cm 2 and E b as large as 285 kV/cm were achieved in 0.1 wt % WO 3 and MnO 2 co-doped AgNbO 3 ceramic. The corresponding W rec reached 2.75 J/cm 3 , which was 1.3 times larger than that of pristine AgNbO 3 ceramics. Moreover, benign thermal stability with W rec = 2.2–2.7 J/cm 3 over 30–150 °C at 240 kV cm −1 was also achieved in 0.1 wt.% WO 3 and MnO 2 co-doped AgNbO 3 ceramics.
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Journal of Energy Storage
·
2021
·
IF 6.583
Jie Xu,Cuili Xiang,Songwen Fang,Luping Zhu,Fen Xu,Lixian Sun,Yongjin Zou,Jian Zhang
Supercapacitors, such as pseudocapacitors (PCs), are widely used because of their excellent electrochemical activity and capacitance; however, it is still challenging to fabricate PCs with high stability and good electrochemical properties. Therefore, suitable templates and transition metal composite materials should be selected for improving their performance. Binary transition metal sulfides exhibit excellent electrochemical performance owing to their rich valence, electrical conductivity, and abundant electrochemical active sites. In this study, we prepared porous Mn-Co-S nanospheres (MCSN) via the hydrothermal method using silica colloidal particles was as the template; to the best of our knowledge, this is the first study to synthesize MCSN. Results suggest that the MCSN composite exhibited excellent conductivity and enhanced stability owing to the porous structure formed by the vertical growth of MnS 2 -CoS 2 nanosheets on silica nanoparticles. The porous MCSN electrode showed an excellent specific capacitance of 1158 F g −1 at 1 A g −1 . Moreover, when coupled with an activated carbon (AC) positive electrode, the supercapacitor of MCSN//AC exhibited stability of 90.4% after 5000 cycles at 10 A g −1 (the specific energy of 34 W h kg −1 at 775 W kg −1 ). Given the results, we believe that the prepared MCSN material has potential application prospects for high-efficiency supercapacitors.
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Journal of Environmental Chemical Engineering
·
2021
·
IF 5.909
Xuan Bie,Kai Wu,Kunling Jiao,Kun Zhao,Xiangyang Chen,Suangchen Ma
Generally, using transition metal oxides as catalysts is the typical method for ammonia-selective catalytic reduction (NH 3 -SCR) under the medium temperature zone (150–400 °C). The controllable structure and uniformly distributed active sites of (Fe&Mn)AlOx-based catalysts via a facilely operative and green prepared method were employed for high NO catalyzed efficiency and selectivity . Among them, the Mn 1.2 Al 0.8 O x sample exhibited excellent low-temperature activity, and Fe 1.2 Al 0.8 O x exhibited excellent N 2 selectivity, which could be ascribed to the unique surface feature (more redox sites on Mn 1.2 Al 0.8 O x and more acid sites on Fe 1.2 Al 0.8 O x ). This creative work has directly demonstrated the importance of coordination between the adsorption of species and electron transportation that emerged on active sites. Meanwhile, the reaction process has been clearly presented in in-situ DRIFTS, declaring the synergetic mechanism (Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism) in the systems. The Eley-Rideal mechanism could be the dominant one due to its rapid reaction rate. The predictable insights are beneficial for profoundly understanding the dual-sites synergetic interaction for controllable conversion rate and high selectivity in the medium temperature SCR process.
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