| 1. |
- Ahmed, Taha, 1984-
(författare)
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Nanostructured ZnO and metal chalcogenide films for solar photocatalysis
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The increasing demand for clean energy and safe water resources has driven the development of efficient and sustainable technologies. Among these technologies, photocatalysis using semiconducting materials has emerged as a promising solution for both solar hydrogen generation and water purification. Low-dimensional ZnO, including nanorods, nanoparticles, and quantum confined particles (so called quantum dots), has demonstrated excellent photocatalytic properties due to their large surface area, high electron mobility, and tunable band gap.The work in this thesis aims to investigate the potential of low-dimensional ZnO alone and in combination with CdS and Fe2O3 for solar hydrogen generation and photocatalytic water purification. The thesis includes a comprehensive analysis of the synthesis, characterization, and optimization of low-dimensional ZnO-based photocatalyst systems for solar hydrogen generation and photocatalytic water purification. Additionally, the thesis will evaluate the performance of the ZnO-based photocatalysts under different experimental conditions, either as photoelectrodes or as distributed particle systems for water purification. The work includes detailed size control of ZnO by itself in dimensions below 10 nm using a hydrothermal method, to provide an increased total surface area and introduce quantum confinement effects that increase the band gap to enable degradation of chemical bonds in a model pollutant in a distributed system for water purification. The work also includes a relatively detailed study of the phonon–phonon and electron–phonon coupling as a function of dimension from 10 nm to 150 nm for ZnO using non-resonant and resonant Raman spectroscopy. Ultimately, the thesis aims to provide insight into the potential of low-dimensional ZnO alone and in combination with other inorganic materials for solar hydrogen generation and photocatalytic water purification and pave the way for the development of efficient and sustainable technologies for clean energy and safe water resources.
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| 2. |
- Blanco, Maria Valeria, et al.
(författare)
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Optimizing carbon coating parameters for obtaining SiO2/C anodes with improved electrochemical performance
- 2021
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Ingår i: Journal of Solid State Electrochemistry. - : Springer Nature. - 1432-8488 .- 1433-0768. ; 25:4, s. 1339-1351
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we present a comprehensive and systematic study on the use of low-cost and highly abundant carbon precursors to obtain SiO2/C anodes with superior electrochemical performance towards Li-ions. Different SiO2/C composites are prepared by soaking silica nanoparticles in solutions containing 20 wt%, 40 wt%, or 60 wt% of glucose, sucrose, or cornstarch, followed by thermal decomposition of the carbohydrates at 850 degrees C or 1200 degrees C. Structural, microstructural, and textural differences on the composites derived from the different carbon coating treatments are related to the electrochemical performance of the anodes. Composites containing final carbon contents close to 15 wt% show a complete coverage of the SiO2 particles with a nanometric carbon layer and exhibit the best electrochemical results. The increase in the annealing temperature from 850 to 1200 degrees C reduces the porosity of the carbon layer and increases its level of ordering, both having positive effects on the overall electrochemical performance of the electrodes. SiO2/C composites coated with 40 wt% sucrose and heat treated at 1200 degrees C display the best electrochemical performance, delivering a reversible specific capacity of 723 mAhg(-1) at 50 mAg(-1) after 100 cycles, which is considerably higher than the reversible capacity of 233 mAhg(-1) obtained with the uncoated material cycled under the same conditions.
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| 3. |
- Fang, Xiao, et al.
(författare)
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Carbon Nitride Nanosheet-Based Photochromic Physical Unclonable Functions for Anticounterfeiting Applications
- 2022
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 5:10, s. 14722-14732
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Tidskriftsartikel (refereegranskat)abstract
- Labels based on physical unclonable functions (PUFs) have been proven to be some of the most effective anticounterfeiting strategies. However, it is still challenging to develop PUF-based anticounterfeiting labels with low prices, simple manufacturing, and easy authentication. Herein, photochromic PUF labels are fabricated by randomly dispersing highly crystalline carbon nitride (HCCN) particles in poly(vinyl acetate) (PVAc). The color of the PVAc/HCCN films originating from photochromism is used as the first layer of safety, which is verified by the naked eye. The pattern of the randomly distributed HCCN particles within the photochromic area (i.e., the PUF) is used as the second layer of security. The PUF can be read out by any smartphone equipped with a portable objective and then automatically authenticated by computer vision technology. We further prove the accurate and feasible authentication of the prepared PUFs and their application potentials.
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| 4. |
- Fang, Xiao, et al.
(författare)
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Homojunction and ohmic contact coexisting carbon nitride for efficient photocatalytic hydrogen evolution
- 2023
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Ingår i: Nano Reseach. - : Springer. - 1998-0124 .- 1998-0000. ; 16, s. 8782-8792
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nitride (CN) has attracted intensive attention as a visible light photocatalyst, but the rapid recombination of photogenerated charge carriers limits its photocatalytic activity. Herein, we develop a new strategy to construct both homojunction and ohmic junction into CN via selectively introducing metallized CN (MCN), which leads to rapid separation and transfer of photogenerated charge carriers. The polymerization of urea in the presence of KOH creates CN homojunction with amino and cyano groups. The subsequent molten salt treatment induces a new type of cyano-terminated CN that can be converted to MCN through photodoping, forming homojunction and ohmic contact coexisting CN (HOCN). The formed HOCN photocatalyst exhibits a high photocatalytic H-2 evolution rate of 18.5 mmol.g(-1).h(-1) under visible light irradiation, 45-fold higher than that of bulk CN. This strategy provides a new idea for designing ohmic contact between semiconductor and metal, and realizing efficient photocatalysis by improving charge separation and transfer.
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| 5. |
- Gond, Ritambhara, et al.
(författare)
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Phosphate-based polyanionic insertion materials for oxygen electrocatalysis
- 2024
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Ingår i: Materials Chemistry Frontiers. - : Royal Society of Chemistry. - 2052-1537. ; 8:5, s. 1153-1170
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Forskningsöversikt (refereegranskat)abstract
- Electrocatalyst-based energy storage technologies such as alkali metal–air batteries, fuel cells, and water splitting devices are the new holy grail in the next-generation energy storage landscape as they deliver higher energy densities than Li-ion/Na-ion batteries (LIBs/SIBs). The new chemistries of energy storage such as metal–air batteries under aqueous or non-aqueous conditions will complement existing LIBs/SIBs owing to the increasing requirement for batteries with high energy density in the present era. Phosphate-based polyanionic frameworks have long been known for their ability to (de)intercalate alkali metal ions. Because of their innate oxygen electrocatalytic activity, these insertion cathode materials have lately emerged as air electrodes in metal–air battery systems. In this review, the present status of phosphate-based polyanionic insertion materials for oxygen reduction and oxygen evolution reaction (ORR and OER) electrocatalysis is summarized. Factors influencing electrocatalytic activity in these materials, such as the presence of different types of alkali metal cations, transition metals, and the type of ligand/mixed anion as well as coordination around the transition metals are discussed. Finally, the development of metal–air batteries derived from phosphate-based polyanionic insertion materials as air electrodes is discussed.
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| 6. |
- Hu, Ya, et al.
(författare)
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Autogenic electrolysis of water powered by solar and mechanical energy
- 2022
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Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 91
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Tidskriftsartikel (refereegranskat)abstract
- A dual-bandgap photoelectrochemical (PEC) cell with two semiconductors stacked in tandem is a widely adopted concept to capture a large fraction of the solar spectrum for water splitting. While two photons are theoretically needed to produce one H2 molecule using single-bandgap PEC cells, four photons are generally required for one H2 molecule in the dual-bandgap cells because of an unavoidable charge recombination at the solid-solid interface. Here, triboelectric effects are exploited in the form of triboelectric nanogenerator (TENG) to allow for the generation of one H2 molecule at the expenses of two photons in a dual-bandgap device using an array of core/shell p-type silicon/anatase-TiO2 nanowires as photoelectrode. The TENG, that converts mechanical energy to electricity, efficiently suppresses the charge recombination at the interface and significantly increases the energy of the photo-generated carriers required for the simultaneous water reduction and oxidation. The synergy of photoexcitation and triboelectrics results in a rate of hydrogen production in a neutral Na2SO4 electrolyte around 150 times higher than that of the counterpart, i.e., the device in the absence of TENG. Furthermore, the TENG-induced enhancement in the PEC water splitting remains substantial even when the solar power density is reduced to 20 mW/cm2.
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| 7. |
- Jian, Jinpeng, et al.
(författare)
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Enhancing Li-S battery performance via functional polymer binders for polysulfide inhibition
- 2024
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Ingår i: Journal of Energy Chemistry. - : Elsevier. - 2095-4956 .- 2096-885X. ; 97, s. 228-236
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Tidskriftsartikel (refereegranskat)abstract
- The commercialization of lithium -sulfur (Li -S) batteries faces several challenges, including poor conductivity, unexpected volume expansion, and continuous sulfur loss from the cathode due to redox shuttling. In this study, we introduce a novel polymer via a simple cross -linking between poly(ether-thioureas) (PETU) and poly(3,4-ethylenedioxythiophene)- poly(styrenesulfonate) (PEDOT:PSS) as a bifunctional binder for Li -S batteries (devotes as "PPTU"). Compared to polyvinylidene fluoride (PVDF), as -prepared PPTU exhibits significantly higher electrical conductivity, facilitating electrochemical reactions. Additionally, PPTU demonstrates effective adsorption of lithium polysulfides, leading to improved cycling stability by suppressing the shuttling effect. We investigate this behavior by monitoring morphological changes at the cell interface using synchrotron X-ray tomography. Cells with PPTU binders exhibit remarkable rate performance, desired reversibility, and excellent cycling stability even under stringent bending and twisting conditions. Our work represents promising progress in functional polymer binder development for Li -S batteries. (c) 2024 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 8. |
- Jin, Feng, et al.
(författare)
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Enhanced rate capability and high-voltage cycling stability of single-crystal nickel-rich cathode by surface anchoring dielectric BaTiO3
- 2022
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 619, s. 65-74
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Tidskriftsartikel (refereegranskat)abstract
- The single-crystal Ni-rich Li(NixCoyMn1_x_y)O-2 cathode (NCM) demonstrates better cycle performance, enhanced tap density and improved mechanical structure stability, compared with polycrystalline NCM. However, limited Li+ transports, (003) plane slips and microcracks in large single particles hinder rate capability and cycle performance. To overcome these shortcomings, single-crystal NCM cathodes have been modified by nanosized tetragonal BaTiO3. Due to the dielectric properties, BaTiO(3 )particles induce electric field concentration at the BaTiO3-NCM-electrolyte interface. Thus, a large amount of lithium vacancies can be formed, providing sufficient sites for the hopping diffusion of lithium ions, thereby significantly enhancing the diffusion coefficient of Li+. Moreover, the redistribution of charges can inhibit the formation and accumulation of cathode-electrolyte-interface. Owing to the synergetic effect of BaTiO3, the BT-modified single-crystal NCM with the optimized loading shows a remarkable initial discharge capacity of 138.5 mAh g(_1) and maintains 53.8% of its initial discharge capacity after 100 cycles under 5C at 4.5 V cut-off voltage. Overall, the proposed dielectric cathode-electrolyte-interface strategy can enhance Li+ ion transport and stabilize the interface structure, leading to improved rate performance. Meanwhile, the diffusion-induced state of charge gradient can also be inhibited, resulting in high structure stability of single-crystal NCMs under high rate and cut-off voltage cycling. (C) 2022 Elsevier Inc. All rights reserved.
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| 9. |
- Kim, Hee Jae, et al.
(författare)
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Lithium dendritic growth inhibitor enabling high capacity, dendrite-free, and high current operation for rechargeable lithium batteries
- 2022
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Ingår i: Energy Storage Materials. - : Elsevier. - 2405-8289 .- 2405-8297. ; 46, s. 76-89
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Tidskriftsartikel (refereegranskat)abstract
- There is no doubt that lithium-metal batteries (LMBs) are considered as attractive power sources owing to their ex-traordinarily high energy density. However, the formation of lithium dendrites during repeated plating/stripping processes hinders their practical application. Herein, we introduce phosphorous pentoxide (P2O5) as an addi-tive to commercial carbonate-based electrolytes to effectively suppress the dendritic growth on the surface of a lithium-metal anode. Significant improvement of the lifespan and coulombic efficiency of the cell were observed with the addition of P2O5 to the electrolyte in Li || Li, Li || Type 316L SS, Li || Cu, and Li || graphite cells. According to surface analyses and microscopic studies, we found reduction mechanism of the P2O5-induced solid-electrolyte interphase (SEI) formation on Li metal. Namely, electrolytic decomposition product, LiF, reacts with P2O5 addi-tive in electrolyte, so that LiPO2F2 is produced by following reaction: 6LiF + 2P(2)O(5) ->& nbsp;3LiPO(2)F(2) + Li3PO4, of which those products suppress dendritic growth of lithium as visualized by operando Synchrotron tomography. The compatibility and outstanding rate performance of the additive-based electrolyte were also demonstrated in Li || NCM full cells. As a result, this finding confirms an effective way to stabilize SEI layers in LMBs via a facile and inexpensive route.
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| 10. |
- Li, Dan, et al.
(författare)
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A bifunctional MnxCo3-xO4-decorated separator for efficient Li-LiI-O2 batteries : A novel strategy to promote redox coupling and inhibit redox shuttling
- 2022
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 428
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Tidskriftsartikel (refereegranskat)abstract
- Although redox mediator (RM) strategy can decrease the overpotential in Li-O2 batteries by tuning the electrochemical formation/degradation of Li2O2 from the circumscribed surface pathway to the solution one, the redox shuttling causes an unexpected RM degradation and a continuous deterioration of Li anode, finally leading to a poor cyclability. This work presents the first report detailing the development of a novel MnxCo3-xO4-decorated separator for Li-LiI-O2 batteries. Benefiting from the promotion effect of MnxCo3-xO4 nanocages on I−/I3− and I3−/I2 redox coupling, the cell with as-prepared separator maintains a low charge potential of ~3.3 V till the death of cell cycling. In addition, as-prepared separator can efficiently restrain the redox shuttling, leading to an obvious improvement on cycling stability for the cell. Moreover, the contributions of LiI to the battery performance and the operation mechanism are systematically investigated. These results present a promising progress in the development of multi-functional separator materials for RM-involved Li-O2 batteries and the new design of hybrid energy storage device.
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