Separations
·
2025
·Vol. 12
·期 12
·
IF 2.7
Meiqing Chen,Wenjie Dai,Yingying Liu,Guanzheng Zhuang,Yanfu Wei,Zhi Dang,Pingxiao Wu
Birnessite has a strong ability to fix rare-earth elements (REEs), but the transformation process of birnessite and its effects on the migration of these elements are not well understood. This study examines how pH and Mn(II) concentrations influence the transformation of cerium-adsorbed hexagonal birnessite (Ce/HB) and the behaviors of Ce and Mn. The results show that the effect of Mn(II) on Ce/HB transformation strongly depended on solution pH. At a pH of 5.0, HB initially underwent transformation into feitknechtite, followed by further disproportionation that resulted in the regeneration of HB and Mn(II). Concurrently, redox reactions occur between Mn(IV) in MnO2(a secondary phase of HB) and Ce(III)/Mn(II), creating a local redox gradient that facilitates partial HB transformation. At pH = 7.0, Mn(II) reduces the crystallinity of transformed products while enhancing the thermodynamic stability of feitknechtite, making it the dominant manganese oxide phase. At pH = 9.0, high-concentration Mn(II) causes lattice distortion in original HB; Ce(III) acts as a structural inducer, promoting mineral transition from hexagonal to orthorhombic symmetry, while excess soluble Mn(II) precipitates new feitknechtite. Additionally, surplus Mn(II) could engage in interfacial redox reactions with high-valent manganese oxides to generate secondary feitknechtite. Ce primarily exists as Ce(IV), forming CeO2on the mineral surface via oxidation reactions that significantly increase hydroxylation and surface reactivity. This study clarifies the transformation pathways of manganese oxides and the migration and transformation patterns of Ce and Mn in rare-earth-rich mining areas.
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ENERGY & FUELS
·
2020
·
IF 3.421
Chunhao Wang,Xiang Xu,Yang Guo,Fan Zhou,Hongyu Chen,Haoyang Li,Zheng Zeng,Liqing Li
The cobalt carbide (Co2C) innovatively prepared from Co–Mn layered double hydroxide (CoMn LDH) has been investigated and evaluated toward its alternative synthesis conditions and different catalytic performances. Along with various characterization techniques, the preparation basically contains four steps (synthesis of CoMn LDH, calcination, reduction, and crystallization) that transform CoMn LDH to CoMn spinel and then to Co2C. Catalyst evaluation toward toluene pyrolysis was conducted. The sample with Co2C exhibited almost 100% conversion rate of toluene, where the resulting hydrogen yield (∼1.8%) is 6 times more than that of the blank test by using silica sand (∼0.3%), realizing the full transfer of hydrogen element from toluene to hydrogen molecule. Furthermore, based on the textural analysis and density functional dispersion correction calculation, which theoretically explained the easy accessibility of toluene to the crystal surface of Co2C(001) with a relatively high adsorption energy (about −280 kJ mol–1), it suggested that Co2C may expand more extensive applications in the field of catalysis.
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ACS Applied Energy Materials
·
2021
·
IF 6.024
Lili Song,Chunlian Peng,Fan Yang,Lian Wang,Yinhua Jiang,Yuqiao Wang
The charge transport between layers of layered double hydroxide (LDH) with structural stability is generally considered as a key factor in restricting electrochemical performances. Herein, we report the surface spatial confinement effect on Mn–Co LDH@carbon dots (CDs) to enhance charge transfer and the stable structure for high-performance supercapacitors. The surface confined effect should be characterized as the charge transfer and interaction between Mn–Co LDH and CDs using density functional theory calculations. CDs can improve the density of states near the Fermi level to achieve an enhanced conductivity. The geometric structure can remain stable at room temperature within 200 fs by using ab initio molecular dynamics simulations. The two-electrode device gained the energy density of 79 W h kg–1 and a power density of 666 W kg–1 at 1 A g–1. This design concept will help to design, prepare, and assemble the high-efficiency and long-lifetime electrochemical energy storage devices based on various layered materials.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2024
·Vol. 35
·期 28
·1-10
·
IF 2.8
Si Weibin,Zhang Zhihua,Wang Yizhao,Shao Meiyang,Wei Jie
Mn–Zn ferrite (Mn 0.6 Zn 0.4 Fe 2 O 4 ) nanoparticles were synthesized using a modified sol–gel method at lower annealing temperature (minimum to 300 ℃). The experimental results and analysis indicate that these nanoparticles exhibit excellent soft magnetic properties with the ultra-high saturation magnetization ( Ms ) up to 45.1 emu/g, demonstrating the significant potential applications for biomedical industry, electronic devices, and wastewater decontamination, etc. More interestingly, Mn 0.6 Zn 0.4 Fe 2 O 4 nanoparticles exhibit unique size-dependent magnetic property, where the saturation magnetization ( Ms ) decreases with the decreasing crystalline size. Furthermore, there exists a linear proportional relationship between Ms and the reciprocal of the crystalline size (1/ D ). A novel theoretical model is subsequently proposed in the paper to elucidate the size-dependent magnetic property. Such magnetic nanoparticles composed of small-sized nanocrystalline can be analogized to a “core–shell” structure, in which the surface or interfacial state increases rapidly in proportion to the overall system. The magnetic moments are irregularly arranged in the “shell” that consists of abundant surface or interfacial states, so-called ‘magnetic disorder shell’. On the contrary, the ferrite “core” is a ferrimagnetically ordered region with a regular arrangement of magnetic moments, which is called as ‘magnetic order core’. With the decrease of crystalline size, the proportion of the ‘magnetic disorder shell’ increases. As a result, the magnetic property of the whole ferrite nanoparticle is weakened. It is believed that the present works contribute to the advancement of comprehending the correlation between the structure and property in magnetic nanoparticles.
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NEW JOURNAL OF CHEMISTRY
·
2024
·
IF 2.7
Junde Zhang,Xuejiao Xu,Dandan Liu,Aoze Wang,Shunyi Zhu,Guangming Nie
Transition metal sulfides (TMS) have garnered increasing attention in recent years as promising alternatives to traditional noble metal-based electrocatalysts for hydrogen evolution. In this paper, Mn-NiS2 nanocomposites were synthesized via a one-step hydrothermal method. The incorporation of manganese into transition metal sulfides improved the surface active area and conductivity of the nanoparticles, creating additional hydrogen evolution sites and enhancing their catalytic performance. The results showed that the Mn0.5-NiS2 electrode exhibited good catalytic performance and stability in alkaline environments. Mn0.5-NiS2 electrode showed an overpotential of only 111 mV at a current density of 100 mA cm-2 (η100=111mV), while it could be operated stably for 100 h at a constant voltage density of 100 mV cm-2. This work provides a simple and feasible approach for electrocatalytic materials for effective hydrogen evolution in alkaline environments.
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Energy & Environmental Science
·
2024
·Vol. 17
·期 11
·3807-3818
·
IF 32.4
Shenyang Xu,Zhefeng Chen,Wenguang Zhao,Wenju Ren,Chenxin Hou,Jiajie Liu,Wu Wang,Chong Yin,Xinghua Tan,Xiaobing Lou,Xiangming Yao,Zhihai Gao,Hao Liu,Lu Wang,Zuwei Yin,Bao Qiu,Bingwen Hu,Tianyi Li,Cheng Dong,Feng Pan,Mingjian Zhang
As commercial cathodes with the highest practical capacity, the structural nature of Li-rich Mn-based (LMR) cathodes, composite or solid solution, is still under debate. Due to the extreme structural similarity of two layered-phase components, namely, the monoclinic phase (C2/m) and rhombohedral phase (Rm), no single tool can resolve this concern alone. Herein, we combined multiple advanced techniques to comprehensively study the structural changes during synthesis of LMR cathodes from different aspects such as the elemental distribution, local structure, long-range structure, and short-range structure, revealing a clear process from the formation of two phases to the gradual phase fusion and eventually to a nearly solid solution. Particularly, X-ray pair distribution function (PDF) analysis combined with theoretical simulations reveals for the first time that the transition metal (TM)–TM distance increases with the progress of the phase fusion, which makes the short-range structural change in TM–TM atomic pairs an effective parameter for judging the extent of phase fusion. Eventually, excellent electrochemical performance was achieved by balancing capacity and cycling stability through adjusting the phase fusion to a medium extent in lithium and sodium two layered-phase components. This study establishes an approach to investigate the structural evolution in the complicated multiple-phase system and provides valuable insights into the design and optimization of cathodes by tuning the phase fusion extent.
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IONICS
·
2024
·Vol. 30
·期 4
·2287-2298
·
IF 2.4
Lin Jie,Ding Yihong,Jin Huile,Zeng Tianbiao
The development of inexpensive, highly effective and durable electrocatalysts for hydrogen production via water electrolysis is of paramount importance. Transition metal oxides, owing to their simplicity in preparation and cost-effectiveness, have been widely investigated, particularly cobalt, nickel, and manganese oxides. Inspired by the synergies of the ternary cathode materials of lithium-ion batteries (LiNi x Mn y Co 1- x - y O 2 , NMC), a simple and feasible method was used to prepare a graphite plate as the support, and Ni and Mn were co-doped with Co 3 O 4 as an efficient water decomposition catalyst. Experimental studies indicated that the 10% Ni and 10% Mn co-doped Co 3 O 4 (Co 2.4 Ni 0.3 Mn 0.3 O 4 , CNM-811) exhibited the lowest overpotential in the oxygen evolution reaction (OER), with CNM-811 achieving an overpotential of 338 mV at 30 mA cm −2 in NaOH aqueous solution, the Tafel slope is 79.71 mV dec −1 . In the hydrogen evolution reaction (HER), an overpotential of 190 mV was attained at 10 mA cm −2 . In overall water splitting, a cell voltage of 2.048 V was achieved at 100 mA cm −2 , which was superior to many analogous catalysts reported today.
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Journal of Materials Chemistry A
·
2023
·Vol. 11
·期 25
·13720-13728
·
IF 11.9
Zheng Ma,Yubo Luo,Wang Li,Yingchao Wei,Chengjun Li,Abubakar Yakubu Haruna,Zhihong Zhang,Xin Li,Qinghui Jiang,Junyou Yang
Point defects play an important role in regulating the electrical and thermal transport properties of thermoelectric materials, but it is always restricted by the solubility of dopants in the matrix. Herein, we demonstrate an effective route to enhance the solubility of Mn from 8% up to 30% in AgSbSe2 through entropy-driven alloying with MnSe. It enables us to largely enhance the carrier concentration and electrical conductivity and also reduce the lattice thermal conductivity of AgSbSe2. As a consequence, (AgSbSe2)0.7(MnSe)0.3 has a high ZT of ∼0.96 at 750 K. Moreover, a further enhanced ZT of 1.18 was achieved in (AgSbSe2)0.7(Mn0.99Se)0.3 at 750 K by the introduced Mn vacancies.
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ADVANCED FUNCTIONAL MATERIALS
·
2026
·
IF 19.9
Rendian Wan,Bing Li,Tenghui Yuan,Chaoxia Peng,Liuchen Wang,Bolin Xia,Peirong Chen,Ali Abdelhafiz,Xunhui Xiong,Enzuo Liu,Bote Zhao
Mn oxides are attractive earth-abundant catalysts for the acidic oxygen evolution reaction (OER). However, their durability is constrained by Mn overoxidation under high anodic potential. Here we demonstrate that dynamic La leaching can be harnessed to activate an oxygen-ligand-hole environment in Mn-based oxide (La 0.1 Mn 0.9 O x ), which suppresses Mn overoxidation. Ultraviolet-visible spectra of the electrolyte indicate that incorporating La into γ-MnO 2 shifts the onset potential for Mn VII O 4 − dissolution to a higher value. Operando spectroscopy reveals that La 0.1 Mn 0.9 O x exhibits a much more stable local MnO 6 framework than γ-MnO 2 under OER conditions. Theoretical analysis indicates that, upon Mn-site oxidation, La-leaching-induced metal vacancies amplify oxygen-ligand holes within distorted La─O─Mn motifs, enabling O-to-Mn charge compensation that suppresses Mn overoxidation. The electronic reconfiguration also modulates the Mn d -band center to optimize intermediate adsorption. La 0.1 Mn 0.9 O x delivers an overpotential 66 mV lower than that of γ-MnO 2 at 10 mA cm −2 geo , and sustains stable operation for 5000 h at 10 mA cm −2 geo and 1400 h at 100 mA cm −2 geo . This work highlights leaching-coupled oxygen-electronic regulation as an effective strategy for designing highly stable and active earth-abundant catalysts in acidic OER.
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Batteries & Supercaps
·
2026
·Vol. 9
·期 6
·e70339
·
IF 4.5
Rongci Wang,Yifu Guo,Leqing Zhang,Fei Wang,Zihao Miao,Xiaoshan Wang,Qiang Li
Manganese-based transition metal oxides have attracted significant interest as promising lithium-ion battery anodes due to their extra capacity beyond theoretical limits. However, the intrinsic origin of extra capacity has remained controversial, particularly the interface electron-transfer mechanisms that have long eluded direct experimental verification owing to the difficulty of electrochemical interface characterization. In this work, we employ advanced operando magnetometry to dynamically analyse spin-dependent electronic behavior in Mn 3 O 4 anode during electrochemical cycling. Our findings identify two synergistic interfacial energy-storage modes underlying the extra capacity, in addition to solid electrolyte interphase (SEI) formation, reversible space-charge storage at the Mn/Li 2 O interface coupled with charge exchange at the Mn/SEI interface. Specifically, electrons first populate spin-split states in metallic Mn at the Mn/Li 2 O interface. With further accumulation, charge transfers across the Mn/SEI interface into the SEI, facilitating SEI growth and contributing to the extra capacity. This study provides the direct magnetic evidence of a multiple-interface cooperative storage mechanism in Mn-based materials, offering a new physical perspective and design strategy for developing high-capacity anode materials through the lens of interfacial electronic structures and spin regulation. Graphical Using operando magnetometry, this work unravels the five-stage electron transfer of Mn 3 O 4 upon Li + insertion/extraction. Interfacial space-charge storage dominates its extra capacity, offering guidance for rational design of Mn-based electrode materials.
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Crystals
·
2026
·Vol. 16
·期 7
·458
·
IF 2.9
Dan Luo,Tao Huang,Shuaigang Ge,Yongqiang Zhao,Bingsuo Zou
The luminescence efficiency of Mn2+-doped metal halides is often limited by concentration quenching caused by Mn-Mn interactions. In this work, the alkaline-earth cadmium chloride BaCd2Cl6·6H2O:Mn2+was synthesized via a mechanical grinding method. The three-dimensional network framework of this compound effectively isolates Mn2+ions with a Mn-Mn separation of 4.87 Å, thereby suppressing concentration quenching. Under 254 nm ultraviolet excitation, the sample exhibits efficient orange emission centered at 588 nm with a photoluminescence quantum yield (PLQY) as high as 98%. Temperature-dependent photoluminescence studies reveal that the optimal emission temperature of this system is 320 K, demonstrating good thermal stability. This work achieves, for the first time, near-unity Mn2+luminescence efficiency in a Ba-site alkaline-earth cadmium halide system, demonstrating that alkaline-earth-site confinement provides an effective strategy for achieving highly efficient Mn-doped halide luminescence.
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Journal of Environmental Chemical Engineering
·
2026
·
IF 7.5
Zhiwei Zhang,Xiang Li,Chenghong Ao,Yan Xie,Duowen Yan,Xinchen Shang,Shakeel Ahmad,Danping Wu,Xinwei Dong,Bo Pan
Mn substitution elevates goethite's surface hydroxyl density versus pure goethite. • More surface hydroxyls on Mn-goethite accelerate humification from precursors. • Mn-goethite serves as oxidant to promote oxypolymerization of humic precursors. • DMSO hydrogen-bond shielding lowers electron transfer and Mn²⁺ release in solution. Electron transfer via hydrogen bonding is crucial for humification. s In nature settings, iron minerals usually coexist with manganese in an isomorphous-replacement manner, attributable to the equal ionic radii of ferric iron and trivalent manganese. Nevertheless, it remains unclear whether abundant surface hydroxyl groups on manganese-substituted iron minerals influence humification. Herein, the abiotic humification of humic precursors with manganese-substituted iron mineral (e.g. Mn-substituted goethite) was systematically investigated for the first time, especially in the role of hydrogen bonding interactions between the mineral and humic precursors. Mn-substituted goethite possessed a greater surface hydroxyl density compared to pure goethite, resulting in a significantly accelerated humification rate. Furthermore, the introduction of a hydrogen bonding shielding agent, such as dimethyl sulfoxide (DMSO), into the reaction system containing humic precursors and the mineral resulted in a marked decrease in both the manganese concentration within the precursor solution and the system’s overall electron transfer capability. These results demonstrated that hydrogen bonding between the mineral and humic precursors enhanced their electron transfer rate, thereby facilitating the humification process. This research offers new insights into abiotic humification mediated by iron/manganese concomitant minerals, enriching the understanding of the global carbon cycle affected by soil geochemical processes. Download: Download high-res image (243KB) Download: Download full-size image
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