| 1. |
- Sanchez, Jaime S., et al.
(författare)
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Versatile electrochemical manufacturing of mixed metal sulfide/N-doped rGO composites as bifunctional catalysts for high power rechargeable Zn–air batteries
- 2024
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Ingår i: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 12:20, s. 11945-11959
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Tidskriftsartikel (refereegranskat)abstract
- The development of rechargeable zinc–air batteries requires air cathodes capable of performing both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with high performance and an extended operational lifespan. Here, we present a cost-effective and versatile electrochemical method for the direct assembly of such electrocatalysts, consisting of nitrogen-doped reduced graphene oxide (NrGO) and mixed transition metal sulfides (NiCoMnSx or NCMS). To this end, we use a small electric bias to electro-deposit both NrGO and NCMS directly on conductive graphene foam, resulting in a perfect porous network and two interpenetrated paths for the easy transport of electrons and ions. The NCMS/ NrGO composite shows one of the highest limiting currents reported so far for a non-noble metal catalyst. Additionally, it exhibits outstanding bifunctional performance for the ORR/OER, superior to both mixed transition metal compounds and noble metals from previous reports. Thus, it serves as a highly efficient air cathode for practical zinc–air batteries featuring high power densities (124 mW cm−2) and long catalyst durability (1560 cycles, around 260 h). We attribute the excellent performance to the synergistic effect between hetero-structured metallic sites and nitrogen dopants. Our approach can be used for preparing efficient zinc–air cathodes on conductive 3D carbon substrates with arbitrary shapes and good performance.
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| 2. |
- Sugawara, Yuuki, et al.
(författare)
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Anion Exchange Membrane Water Electrolyzers: An Overview
- 2023
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Ingår i: Journal of Chemical Engineering of Japan. - 0021-9592. ; 56:1
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Forskningsöversikt (refereegranskat)abstract
- The green-H-2 production through water electrolysis from renewable energies is vital in the context of developing a sustainable and cost-effective methodology. Anion exchange membrane water electrolyzer (AEMWE) is considered as a promising energy conversion device, which can be an alternative to fossil fuel-based energyplatforms. AEMWE can employ inexpensive nonprecious metal catalysts and current collectors, which is preferable forpractical applications of this technology. Membrane electrode assemblies (MEAs) for AEMWE plays a significant role forthe hydrogen production efficiency. Thus, understanding the MEA components, operation, and performance is critical forthe development of prominent materials for the AEMWE. In this review, we highlight the performances of the MEAs andtheir components, such as the AEMs and catalysts with a broad discussion of the progress with current status. Additionally,we also have put forward our assessment to lead the way for future research, to commercialize AEMWE as a provenalternative for the cost-effective production of high-purity hydrogen.
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| 3. |
- Xia, Zhenyuan, 1983, et al.
(författare)
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Green synthesis of positive electrodes for high performance structural batteries - A study on graphene additives
- 2024
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Ingår i: Composites Science and Technology. - 0266-3538. ; 251
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Tidskriftsartikel (refereegranskat)abstract
- Carbon fibres (CF) have the potential to serve as versatile and multifunctional conductive electrodes within the concept of “structural batteries”. These batteries possess the unique ability to both store electrical energy and bear mechanical loads without requiring extra current collectors. However, numerous challenges remain on the path to commercializing structural batteries. One significant challenge lies in the fabrication process of CF-based cathode composites, including the poor adhesion of active materials to the CF surface and the use of hazardous organic solvents, such as N-methyl pyrrolidone (NMP) through traditional blade coating. In this study, we present a sustainable fabrication approach, using electrophoretic deposition (EPD) to construct positive electrode composites with lithium iron phosphate (LiFePO4) and graphene nanosheets. Especially, ethanol was used as a green solvent replacing NMP to minimize the environmental impact. Meanwhile, the influence of different types of graphene additives (three kinds of graphene nanoplatelets (GNP), four kinds of reduced graphene oxide (rGO) and one home-made graphene) to the relative battery performance were evaluated under a systematic comparative analysis. Among the tested graphene additives, LFP/rGO2 based positive electrode exhibits a desirable specific capacity of 126.2 mAhg−1, maintaining over 93% retention even under the demanding conditions of 2C over 500 cycles.
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| 4. |
- Zhang, Daheng, et al.
(författare)
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Producing Bilayer Graphene Oxide via Wedge Ion-Assisted Anodic Exfoliation: Implications for Energy and Electronics
- 2023
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Ingår i: ACS Applied Nano Materials. - 2574-0970. ; 6:21, s. 19639-19650
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical synthesis has emerged as a promising approach for the large-scale production of graphene-based two-dimensional (2D) materials. Electrochemical intercalation of ions and molecules between graphite layers plays a key role in the synthesis of graphene with controllable thickness. However, there is still a limited understanding regarding the impact of intercalant molecules. Herein, we investigated a series of anionic species (i.e., ClO4-, PF6-, BF4-, HSO4-, CH3SO3-, and TsO-) and examined their wedging process between the weakly bonded layered materials driven by electrochemistry. By combining cyclic voltammetry, X-ray diffraction (XRD), and Raman spectroscopy, along with density functional theory (DFT) calculations, we found that stage-2 graphite intercalation compounds (GICs) can be obtained through intercalation of ClO4-, PF6-, or BF4- anions into the adjacent graphene bilayers. The anodic exfoliation step based on ClO4--GIC in (NH4)(2)SO4 (aq.) resulted in the formation of bilayer-rich (>57%) electrochemically exfoliated graphene oxide (EGO), with a high yield (similar to 85 wt %). Further, the physicochemical properties of these EGO can be readily customized through electrochemical reduction and modification with different surfactants. This versatility allows for precise tailoring of EGO, making it feasible for energy and electronic applications such as electrodes in electrochemical capacitors and functional composites in wearable electronics.
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