| 1. |
- A. da Cruz, Marcia Gabriely, et al.
(författare)
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Biocoatings and additives as promising candidates for ultralow friction systems
- 2021
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Ingår i: Green Chemistry Letters and Reviews. - : Informa UK Limited. - 1751-8253 .- 1751-7192. ; 14:2, s. 356-379
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Forskningsöversikt (refereegranskat)abstract
- The achievement of frictionless systems, known as superlubricity, has become of great importance concerning energy saving and emission reduction. In parallel, the drive toward sustainability and environmental aspects has led to intense advances in the research and development of biobased materials. From the standpoint of Green Chemistry principles, this review presents a critical overview of the latest findings and future perspectives on the application of biobased materials aiming at superlubricant pursuits. The progress in the use of biomacromolecules, such as chitosan, cellulose, and lignin, as additives to lubricants or coating materials, are addressed, as well as the advances on sustainable coatings based on diamond-like carbon (DLC). Deeper investigations on the development of non-hazardous processes dedicated to the tribological properties of DLC, such as electrochemical synthesis using environment-friendly solvents to generate molecular precursors, widen the perspectives to achieve sustainable materials. Besides, the exploration of the tribochemical interactions between the DLC surface and lubricants containing biobased materials arises as a promising strategy to achieve green superlubricity as a viable and scalable process, through different pathways: by hydrogen bonds between lubricant and additives, via surface passivation of the functional groups present in these biomacromolecules or by biomimicking natural joints.
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| 2. |
- A. da Cruz, Marcia Gabriely, et al.
(författare)
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On the product selectivity in the electrochemical reductive cleavage of 2-phenoxyacetophenone, a lignin model compound
- 2022
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Ingår i: Green Chemistry Letters and Reviews. - : Informa UK Limited. - 1751-8253 .- 1751-7192. ; 15:1, s. 151-159
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Tidskriftsartikel (refereegranskat)abstract
- Research towards the production of renewable chemicals for fuel and energy industries has found lignin valorization as key. With a high carbon content and aromaticity, a fine-tuning of the depolymerization process is required to convert lignin into valuable chemicals. In context, model compounds have been used to understand the electrocatalyzed depolymerization for mimicking the typical linkages of lignin. In this investigation, 2-phenoxyacetophenone, a model compound for lignin beta-O-4 linkage, was electro-catalytically hydrogenated (ECH) in distinct three-electrode setups: an open and a membrane cell. A deep eutectic solvent based on ethylene-glycol and choline chloride was used to pursue sustainable routes to dissolve lignin. Copper was used as electrocatalyst due to the economic feasibility and low activity towards hydrogen evolution reaction (HER), a side reaction of ECH. By varying the cell type, we demonstrate a simple ECH route for the generation of different monomers and oligomers from lignin. Gas chromatography of the products revealed a higher content of carbonyl groups in those using the membrane cell, whereas the open cell produced mostly hydroxyl-end chemicals. Aiming at high value-added products, our results disclose the cell type influence on electrochemical reductive depolymerization of lignin. This approach encompasses cheap transition metal electrodes and sustainable solvents.
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| 3. |
- A. da Cruz, Márcia G., et al.
(författare)
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Solvent-free synthesis of photoluminescent carbon nanoparticles from lignin-derived monomers as feedstock
- 2023
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Ingår i: Green Chemistry Letters and Reviews. - 1751-8253 .- 1751-7192. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Photoluminescent carbon nanoparticles (CNPs), such as carbon dots (CDs), have attracted much attention owing to a unique set of properties, like high and tunable fluorescence. In this way, the use of carbon-rich lignin has been demonstrated to be a sustainable approach to producing a broad range of photoluminescent CNPs. However, the valorization of this complex polyphenol is limited when it comes to green and efficient ways of conversion. In addition, the existing solvothermal approaches using lignin often result in CDs with low photoluminescence, while flammable and/or toxic solvents are employed. Here, we depolymerized technical lignins, i.e. kraft and soda, through electroreductive cleavage in two different sustainable media: deep eutectic solvent and levulinic acid. After depolymerization, lignin-derived monomers were generated, with a predominance of aryl ether and phenolic groups, which were further combined with 1,2-Phenylenediamine to produce N-doped CNPs in a solvent-free approach. Photoluminescent CNPs with varied sizes were generated (5–50 nm), which presented a wide photoluminescence emission, from blue to red, depending on solvent polarity. These results demonstrate a feasible and sustainable route for the solvent-free synthesis of photoluminescent CNPs using lignin-derived monomers as carbon source, which may find applications in a wide range of fields.
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| 4. |
- Leu, Meike, et al.
(författare)
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Synthesis of luminescent semiconductor nanoparticles in ionic liquids -the importance of the ionic liquid in the formation of quantum dots
- 2021
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Ingår i: Green Chemistry Letters and Reviews. - : Informa UK Limited. - 1751-8253 .- 1751-7192. ; 14:1, s. 128-136
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Tidskriftsartikel (refereegranskat)abstract
- Zinc sulfide (ZnS) and cadmium sulfide (CdS) nanoparticles were synthesized in different ionic liquids (IL) with microwave irradiation. Particle characterization by means of powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and optical spectroscopy (UV-vis absorption and photoluminescence) showed a strong dependence of the particle size depending on the IL employed. Whilst all ILs yielded particles in the nanometer regime and showed in their optical properties quantum confinement, particularly small particles were obtained from choline-base ILs pointing to the strong influence of this IL cation in blocking the particle growth. Here, quantum dots of 1.5–3 nm size were yielded for both, ZnS and CdS.
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| 5. |
- Lu, Can, et al.
(författare)
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Fabrication of semi-transparent SrTaO2N photoanodes with a GaN underlayer grown via atomic layer deposition
- 2022
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Ingår i: Green Chemistry Letters and Reviews. - : Informa UK Limited. - 1751-8253 .- 1751-7192. ; 15:3, s. 658-670
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Tidskriftsartikel (refereegranskat)abstract
- Quaternary metal oxynitride-based photoanodes with a large light transmittance are promising for high solar-to-hydrogen (STH) conversion efficiency in photoelectrochemical (PEC) tandem cells. Transparent substrates to support PEC water-splitting were fabricated using atomic layer deposition (ALD) to synthesize 30 and 60 nm GaN on SiC substrates. A generalized approach was used to grow a quaternary metal oxynitride, i.e. SrTaO2N thin film on the GaN/SiC substrates. The transparency above 60% in the wide solar spectrum highlights its availability of transmitting visible light to the rear side. A photocurrent onset at ca. −0.4 V vs. reversible hydrogen electrode (RHE) was achieved by the SrTaO2N/GaN/SiC photoanodes in a 0.1 M NaOH electrolyte under simulated solar irradiation. This paves the way for the construction of hierarchically nanostructured tandem PEC cells. This work demonstrates the viability of integrating ALD in constructing substrates for semi-transparent quaternary metal oxynitride photoanodes.
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| 6. |
- Risso, Mariela, et al.
(författare)
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Microwave-assisted solvent-free lipase catalyzed transesterification of beta-ketoesters
- 2012
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Ingår i: Green Chemistry Letters and Reviews. - : Taylor & Francis. - 1751-8253 .- 1751-7192. ; 5:4, s. 539-543
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Tidskriftsartikel (refereegranskat)abstract
- Lipase-catalyzed transesterification was used as an efficient tool for the interconversion of beta-ketoesters. Catalytic activity of commercial lipase B from Candida antarctica (Novozym 435) was evaluated in systems involving non activated acyl donors, and enhanced using microwave irradiation. Interestingly, the combination of CAL B in microwave irradiation worked excellent in solvent-free conditions, thus assuring a highly competitive and environment-friendly process with high yields (up to 96%) in competitive times (< 2h). The combination of biocatalysis with solvent-free systems and microwave assistance is currently scarcely used, and may represent a powerful synergy for preparative reactions.
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| 7. |
- Yong, Jean W.H
(författare)
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Integrating organic chemical-based socio-scientific issues comics into chemistry classroom: expanding chemists’ toolbox
- 2021
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Ingår i: Green Chemistry Letters and Reviews. - : Informa UK Limited. - 1751-8253 .- 1751-7192. ; 14, s. 699-709
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Tidskriftsartikel (refereegranskat)abstract
- Over the past decades, there had been a growing concern for policy makers and scientists to implement the sustainable development (SD) agenda. To date, little efforts are made to instil early awareness and education for sustainable development (ESD) amongst the first-year undergraduates to become effective and responsible global citizens. As such, the learning of organic chemical-based socio-scientific issues (SSIs) within the scientific world is important to promote early awareness amongst chemistry undergraduates in SD. In this manuscript, for the first time comics drawing is being used as learning instruction to instil the ESD learning amongst first-year undergraduates at Universiti Malaysia Terengganu. In this activity, students made their own comics with regard to organic chemical-based SSIs they have read and shared their own comics, together with their reflective essays on the learning management system (LMS). Based on a survey result, students’ involvement in the current activity has resulted in their familiarity with the organic chemical-based SSIs. In addition, they have expressed a high degree of satisfaction toward the implemented activity and the chemistry content they learnt in this course based on the reflective essay received by the course instructor in the LMS.
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| 8. |
- Yuan, Yusheng, et al.
(författare)
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Protein-based luminescent aerogels with elastic properties
- 2022
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Ingår i: Green Chemistry Letters and Reviews. - : Taylor & Francis Ltd. - 1751-8253 .- 1751-7192. ; 15:3, s. 508-518
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Tidskriftsartikel (refereegranskat)abstract
- Gelatin is a famous gel-forming proteinaceous material with excellent hydrogelation properties. Herein, we report that protein nanofibrils (PNFs) can be employed to form hybrids with gelatin that can be converted to aerogels with attractive mechanical properties. Moreover, we are able to influence the gelation behavior of PNFs by mechanochemical processing. A combination of mechanochemistry and aqueous self-assembly is employed to prepare PNFs functionalized with hydrophobic dyes. These materials are then mixed with gelatin and converted into aerogels by freeze drying. We find that PNFs functionalized with PNFs lead to the formation of aerogels with more robust mechanical properties. Mechanochemical methodology as a green and scalable method can thus be employed for influencing the properties of protein-based aerogels. This represents a new and highly flexible and novel strategy for tuning both properties and functionality of protein materials. This work opens a simple and feasible way to produce nontoxic and biodegradable aerogel materials with favorable mechanical strength.
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