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1.
Jingliang Xu Xinhang Hu Md Asraful Alam Gul Muhammad Yongkun Lv Minghai Wang Chenjie Zhu Wenlong Xiong 《RSC advances》2021,11(56):35280
Zn/MnO2 batteries, one of the most widely studied rechargeable aqueous zinc-ion batteries, suffer from poor cyclability because the structure of MnO2 is labile with cycling. Herein, the structural stability of α-MnO2 is enhanced by simultaneous Al3+ doping and lignin coating during the formation of α-MnO2 crystals in a hydrothermal process. Al3+ enters the [MnO6] octahedron accompanied by producing oxygen vacancies, and lignin further stabilizes the doped Al3+via strong interaction in the prepared material, Al-doped α-MnO2 coated by lignin (L + Al@α-MnO2). Meanwhile, the conductivity of L + Al@α-MnO2 improves due to Al3+ doping, and the surface area of L + Al@α-MnO2 increases because of the production of nanorod structures after Al3+ doping and lignin coating. Compared with the reference α-MnO2 cathode, the L + Al@α-MnO2 cathode achieves superior performance with durably high reversible capacity (∼180 mA h g−1 at 1.5 A g−1) and good cycle stability. In addition, ex situ X-ray diffraction characterization of the cathode at different voltages in the first cycle is employed to study the related mechanism on improving battery performance. This study may provide ideas of designing advanced cathode materials for other aqueous metal-ion batteries.Al3+ doping combined with lignin coating improves the structural stability and electrochemical performance of the modified α-MnO2, L + Al@α-MnO2. 相似文献
2.
An inexpensive and eco-friendly alternative energy storage solution is becoming more in demand as the world moves towards greener technology. We used first principles calculations to investigate α, β, and γ-MnO2 and their Al-ion intercalation mechanism in potential applications for aluminum batteries. We explored these complexes through investigating properties such as volume change, binding/diffusion energy, and band gap to gauge each material. α-MnO2 had almost no volume change. γ-MnO2 had the lowest binding energy and diffusion barrier. Our study gives insight into the feasibility of using MnO2 in aluminum batteries and guides investigation of the material within its different phases.An inexpensive and eco-friendly alternative energy storage solution is becoming more in demand as the world moves towards greener technology. 相似文献
3.
Zr4+ doped α-MnO2 nanowires were successfully synthesized by a hydrothermal method. XRD, SEM, TEM and XPS analyses indicated that Mn3+ ions, Mn4+ ions, Mn4+δ ions and Zr4+ ions co-existed in the crystal structure of synthesized Zr4+ doped α-MnO2 nanowires. Zr4+ ions occupied the positions originally belonging to elemental manganese in the crystal structure and resulted in a mutual action between Zr4+ ions and Mn3+ ions. The mutual action made Mn3+ ions tend to lose their electrons and Zr4+ ions tend to get electrons. Cathodic polarization analyses showed that the electrocatalytic activity of α-MnO2 for oxygen reduction reaction (ORR) was remarkably improved by Zr4+ doping and the Zr/Mn molar ratio notably affected the ORR performance of the air electrodes prepared by Zr4+ doped α-MnO2 nanowires. The highest ORR current density of the air electrodes prepared by Zr4+ doped α-MnO2 nanowires in alkaline solution appeared at Zr/Mn molar ratio of 1 : 110, which was 23% higher than those prepared by α-MnO2 nanowires. EIS analyses indicated that the adsorption process of O2 molecules on the surface of the air electrodes prepared by Zr4+ doped α-MnO2 nanowires was the rate-controlling step for ORR. The DFT calculations revealed that the mutual action between Zr4+ and Mn3+ in Zr4+ doped α-MnO2 nanowires enhanced the adsorption process of O2 molecules.O2 adsorption was enhanced after doping Zr4+ into MnO2 nanowires subsequently led to the improvement of ORR catalytic performance. 相似文献
4.
Reversible aqueous zinc-ion batteries (ZIBs) have great potential for large-scale energy storage owing to their low cost and safety. However, the lack of long-lifetime positive materials severely restricts the development of ZIBs. Herein, we report NaV6O15 microflowers as a cathode material for ZIBs with excellent electrochemical performance, including a high specific capacity of ∼300 mA h g−1 at 100 mA g−1 and 141 mA h g−1 maintained after 2000 cycles at 5 A g−1 with a capacity retention of ∼107%. The high diffusion coefficient and stable tunneled structure of NaV6O15 facilitate Zn2+ intercalation/extraction and long-term cycle stability.NaV6O15 microflowers were synthesized as a stable cathode material for aqueous zinc ion batteries, which show a high specific capacity and excellent long-term cycling performance. 相似文献
5.
Weijun Zhou Jizhang Chen Minfeng Chen Xinwu Xu Qinghua Tian Junling Xu Ching-Ping Wong 《RSC advances》2019,9(52):30556
Aqueous zinc-ion batteries offer a low-cost and high-safety alternative for next-generation electrochemical energy storage, whereas suitable cathode materials remain to be explored. Herein, rod-like anhydrous V2O5 derived from a vanadium-based metal–organic framework is investigated. Interestingly, this material is assembled by tiny nanosheets with a large surface area of 218 m2 g−1 and high pore volume of 0.96 cm3 g−1. Benefiting from morphological and structural merits, this material exhibits excellent performances, such as high reversible capacity (449.8 mA h g−1 at 0.1 A g−1), good rate capability (314.3 mA h g−1 at 2 A g−1), and great long-term cyclability (86.8% capacity retention after 2000 cycles at 2 A g−1), which are significantly superior to the control sample. Such great performances are found to derive from high Zn2+ ion diffusion coefficient, large contribution of intercalation pseudocapacitance, and fast electrochemical kinetics. The ex situ measurements unveil that the intercalation of Zn2+ ion is accompanied by the reversible V5+ reduction and H2O incorporation. This work discloses a direction for designing and fabricating high-performance cathode materials for zinc-ion batteries and other advanced energy storage systems.V2O5 with intriguing micro/nano-hierarchical structure is fabricated via the pyrolysis of MIL-47 (a MOF material) and displays great performances as the cathode material for aqueous zinc-ion batteries. 相似文献
6.
Hao-wen Jiang Yan Yang Yi-ming Nie Zhi-fang Su Yun-fei Long Yan-xuan Wen Jing Su 《RSC advances》2022,12(10):5997
As a non-active material component, the binder can effectively maintain the integrity of battery electrodes. In this work, based on the inspired structure of fishing nets, a three-dimensional mesh adhesive using widely sourced raw materials CMC and β-CD was designed. These cross-linked cyclodextrins have the advantage of dispersing the stress at the anchor point and moderating the significant volume changes of the Si anode. The Si/β-CD-CMC electrode maintains a reversible capacity of 1702 mA h g−1 even after 200 cycles at a high current of 0.5C. This work represents a significant step forward in Si anode binders and enables the cross-linked cyclodextrins to have potential applications in energy storage systems.A three-dimensional mesh β-CD-CMC adhesive was designed based on the structure of fishing nets. This cross-linked binder has the ability to disperse the stress at the anchor point and moderate the significant volume changes of the Si anode. 相似文献
7.
γ-MnO2, which is commercially used as an electrode material in batteries, is produced using large amounts of energy and leads to the production of high pollution as a secondary product. Ideally, this material should be fabricated by energy efficient, non-polluting methods at a reasonable cost. This study reports the green fabrication of γ-MnO2 into a gas diffusion electrode with Pt-free catalysts in acid solution. Cobalt oxide nanoparticles were deposited on few-layer graphene sheets produced via a simple sintering and ultrasonic mixing method, leading to the fabrication of cobalt oxide/few-layer graphene. Co3O4 nanoparticles are irregularly shaped and uniformly distributed on the surface of the few-layer graphene sheets. Characterization was conducted by X-ray diffraction, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy. Electrochemical characterization revealed the performance of cobalt oxide/few-layer graphene gas diffusion electrode in an electrolyte of 120 g L−1 manganese sulfate + 30 g L−1 sulfuric acid at 100 A m−2 at 80 °C. The cobalt oxide/few-layer graphene gas diffusion electrode exhibited a lower cell voltage of 0.9 V and higher electric energy savings of approximately 50% compared with traditional cathodes (copper and carbon).Co3O4/FLG was used as a nanocatalyst to catalyze the ORR in the electrodeposition of MnO2. The proposed Co3O4/FLG nanocomposite GDE exhibited a high activity of 0.9 V at a current density of 100 A m−2. 相似文献
8.
This work reports the layer-tunnel conversion of porous dehydrated synthetic alkali-free δ-MnO2 analogs prepared by exfoliation, flocculation, and heat treatment of nanosheets derived from highly crystalline potassium birnessite. High surface area porous solids result, with specific surface areas of 90–130 m2 g−1 and isotherms characteristic of both micro and macropores. The microstructures of the re-assembled floccules are reminiscent of crumpled paper where single and re-stacked nanosheets form the walls of interconnected macropores. The atomic and local structures of the floccules heat treated from 60–400 °C are tracked by Raman spectroscopy and synchrotron X-ray total scattering measurements. During heating, the nanosheets comprising the pore walls condense to form tunnel-structured fragments beginning at temperatures below 100 °C, while the microstructure with high surface area remains intact. The flocc microstructure remains largely unchanged in samples heated up to 400 °C while an increasing fraction of the sample is transformed, at least locally, to possess 1D tunnels characteristic of α-MnO2. Cyclic voltammetry in Na2SO4 aqueous electrolyte reflects the nanoscale structural evolution, where intercalative pseudocapacitance diminishes with the degree of transformation. Collectively, these results demonstrate that it is feasible to tailor the materials for applications incorporating nanoporous solids and nanofluidics, and specifically imply strategies to maintain a kinetically accessible interlayer contribute to Na intercalative pseudocapacitance.This work reports the layer-tunnel conversion of porous dehydrated synthetic alkali-free δ-MnO2 analogs prepared by exfoliation, flocculation, and heat treatment of nanosheets derived from highly crystalline potassium birnessite. 相似文献
9.
γ-MnO2 nanomaterials play an essential role in the development of advanced electrochemical energy storage and conversion devices with versatile industrial applications. Herein, novel dandelion-like hollow microspheres of γ-MnO2 mesocrystals have been fabricated for the first time by a one-pot biomineralization route. Recombinant collagen with unique rod-like structure has been demonstrated as a robust template to tune the morphologies of γ-MnO2 mesocrystals, and a very low concentration of collagen can alter the nanostructures of γ-MnO2 from nanorods to microspheres. The as-prepared γ-MnO2 mesocrystals formed well-ordered hollow microspheres composed of delicate nanoneedle-like units. Among all the reported γ-MnO2 with various nanostructures, the γ-MnO2 microspheres showed the most prowess to maintain high discharge capacities after 100+ cycles. The superior electrochemical performance of γ-MnO2 likely results from its unique hierarchical micro-nano structure. Notably, the γ-MnO2 mesocrystals display high biocompatibility and cellular activity. Collagen plays a key dual role in mediating the morphology as well as endowing the biofunction of the γ-MnO2 mesocrystals. This environmentally friendly biomineralization approach using rod-like collagen as the template, provides unprecedented opportunity for the production of novel nanostructured metal oxides with superior biocompatibility and electrochemical performance, which have great potential in advanced implantable and wearable health-care electronic devices.Recombinant collagen with unique rod-like structure has been demonstrated as a robust template to create novel dandelion-like hollow microspheres of γ-MnO2 mesocrystals, which display superior biocompatibility and electrochemical performance. 相似文献
10.
This work is primarily focused on indium sulfide (β-In2S3) and cobalt (Co)-doped β-In2S3 nanoflakes as photoanodes for water oxidation. The incorporation of cobalt introduces new dopant energy levels increasing visible light absorption and leading to improved photo-activity. In addition, cobalt ion centers in β-In2S3 act as potential catalytic sites to promote electro-activity. 5 mol% Co-doped β-In2S3 nanoflakes when tested for photoelectrochemical water splitting exhibited a photocurrent density of 0.69 mA cm−2 at 1.23 V, much higher than that of pure β-In2S3.Doped indium sulfide as an efficient photocatalyst for water oxidation. 相似文献
11.
An efficient [4 + 2] benzannulation of α-cyano-β-methylenones and α,β-unsaturated aldehydes was achieved under metal-free reaction conditions selectively delivering a wide range of polyfunctional benzenes in high yields respectively (up to 94% yield).An efficient [4 + 2] benzannulation of α-cyano-β-methylenones and α,β-unsaturated aldehydes was achieved under metal-free reaction conditions selectively delivering a wide range of polyfunctional benzenes in high yields respectively (up to 94% yield).Multi-substituted benzenes are privileged structural units ubiquitous in pharmaceuticals,1 natural products2 and advanced functional materials.3 Various excellent methodologies have been investigated for the construction of functionalized aromatics including nucleophilic or electrophilic substitution,4 transition metal-catalyzed coupling reactions5 and directed metalation.6 However, the widespread application of these strategies established thus far suffer from the limitations of functional groups introduced on the pre-existing benzene and regioselectivity issues. Among various synthetic methods, tandem benzannulation reactions arguably represent an attractive alternative to classical methods for rapid construction of polysubstituted benzenes in an atom-economical fashion.7 This protocol featuring an efficient transformation of acyclic building blocks into structurally valuable benzene skeletons. In this context, α-cyano-β-methylenones has been employed as substrates to format six-membered ring in tandem cyclization reactions due to the activation of the pronucleophile methyl group. In 2015, Tong and co-workers developed a phosphine-catalyzed addition/cycloaddition domino reactions of β′-acetoxy allenoate with 2-acyl-3-methyl-acrylonitriles to give 2-oxabicyclo[3.3.1]nonanes (Scheme 1a).8 Soon after that, the construction of benzonitrile derivatives and 1,3,5-trisubstituted benzenes via N-heterocyclic carbene catalysis has been reported by the groups of Wang and Ye independently (Scheme 1b).9 Then the synthesis of 1,3,5-trisubstituted benzenes by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-mediated annulation of α-cyano-β-methylenones and α,β-unsaturated carboxylic acids was also developed by Ye and co-workers (Scheme 1c).10 Shi et al. reported a base-promoted tandem cyclization reaction of α-cyano-β-methylenones and α,β-unsaturated enones, which have electron-withdrawing group (EWG), accessing to a wide range of benzonitriles in a different C–C bond formation process (Scheme 1d).11 As part of our ongoing interest in harnessing enones for developing new methodologies for the construction of functionalized benzenes, we have recently demonstrated NHC-catalyzed convenient benzonitrile assembly in the presence of oxidant.9a While the same reaction of enals and α-cyano-β-methylenones was conducted in the basic condition without NHC, a novel polyfunctionalized benzene product was obtained (Scheme 1e). The result inspired us to extend the synthetic potential of benzannulation strategy to access diverse benzonitriles, particularly from simpler, abundantly available starting materials.Open in a separate windowScheme 1α-Cyano-β-methylenones in cycloaddition domino reactions.At the outset, model reaction of 2-benzoyl-3-phenylbut-2-enenitrile 1a and cinnamaldehyde 2a was used to evaluate reaction parameters. Key results of condition optimization are summarized in 12 The configuration of products were assigned unambiguously by X-ray analysis of the product 3a. A quick solvent screening demonstrated that chloroform is the best choice to produce the benzannulation product 3a in a desirable yield (entries 10–13, †). Reducing the loading of the cinnamaldehyde or NaOH to 1.2 equivalence led to dramatical loss of the yield (entries 14 &15, Entry Base Solvent Time (h) Yieldb (%) 1 Cs2CO3 Toluene 24 70 2 Na2CO3 Toluene 24 42 3 K2CO3 Toluene 24 38 4 NaOH Toluene 12 78 5 NaOAc Toluene 24 52 6 KOH Toluene 12 74 7 K3PO4 Toluene 24 58 8 DBU Toluene 24 33 9 Et3N Toluene 48 46 10 NaOH DCM 12 88 11 NaOH CHCI 3 12 94 12 NaOH DCE 12 84 13 NaOH H2O 48 0 14c NaOH CHCI3 12 85 15d NaOH CHCI3 12 84 16e NaOH CHCI3 12 80