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Browsing by Publisher "Royal Society of Chemistry"

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Analysis of artemisinin by a packed-column supercritical fluid chromatography-atmospheric pressure chemical ionisation mass spectrometry technique
(Royal Society of Chemistry, 2003) Dost K.; Davidson G.
A packed-column supercritical fluid chromatography-atmospheric pressure chemical ionisation mass spectrometry method was studied for the determination of artemisinin from Artemisia annua L. extracts. The technique does not require any kind of derivatisation prior to the analysis. All samples were simply dissolved in methanol and injected into the mobile phase. Detection was achieved by using mass spectrometry with atmospheric pressure chemical ionisation. The ionisation technique is relatively soft and provides protonated molecular ion and informative structural fragmentation for the compound. Benzophenone was used as a chromatographic standard for the determination of the analytical reproducibility. The supercritical carbon dioxide mobile phase used in the system was modified by 10% methanol. The average absolute retention time was 3.54 min with a standard deviation of 0.017 min and a relative standard deviation of 0.4% with respect to benzophenone for the procedure. The correlation coefficient was 0.998 and detection limit 370 pg on column.
Centri-voltammetric determination of molybdenum
(Royal Society of Chemistry, 2013) Koçak S.; Ertaş F.N.
Centri-voltammetry is a method developed in the last decade which combines the advantages of centrifugation and voltammetry and hence provides a practical way for application of co-precipitation in trace analysis allowing direct voltammetric scan. The present study describes another application of the centri-voltammetric method for the determination of biologically essential trace elements, in particular, molybdenum ion. For this purpose, a dual-functional voltammetric cell adjustable to the centrifuge was designed and utilized in the determination of molybdenum ions with various carrier reagents, i.e. oxine, pyrogallol red, and cupferron. Optimization studies include solution properties as well as voltammetric measurement and centrifugal parameters. Among the reagents studied, the best results were obtained with pyrogallol red and the reduction peak current of the complex was utilized for analytical purposes. The limit of detection from calibration curves was calculated to be 9.4 × 10-9 M and a better sensitivity was obtained in the presence of chlorate ions that are known to have a catalytic effect on the reaction. The method was employed in the determination of molybdenum in milk samples and the results were compared with those obtained by the ICP-MS method. © The Royal Society of Chemistry 2013.
Epichlorohydrin crosslinked chitosan-clay composite beads for on-line preconcentration and determination of chromium(iii) by flow injection flame atomic absorption spectrometry
(Royal Society of Chemistry, 2014) Cittan M.; Tirtom V.N.; Dinçer A.; Çelik A.
An on-line flow injection preconcentration-flame atomic absorption spectrometry (FI-AAS) method is developed for trace determination of chromium(iii) by sorption on a mini-column packed with epichlorohydrin (ECH) crosslinked chitosan-clay composite beads. The factors affecting preconcentration of Cr(iii) ions such as sample and eluent flow rate, loading time, sample and eluent pH, and eluent type and concentration were investigated. The Cr(iii) ions were eluted from the mini-column with 0.1 M EDTA. Under the optimized parameters, the calibration graph using the preconcentration system for Cr(iii) was linear with a correlation coefficient of 0.9982. Detection and quantification limits of the method were obtained to be 0.0162 and 0.0929 μg mL-1 respectively, with an enrichment factor of 13.4. © 2014 The Royal Society of Chemistry.
Phenolic composition, antioxidant and enzyme inhibitory activities of ethanol and water extracts of: Chenopodium botrys
(Royal Society of Chemistry, 2016) Ozer M.S.; Sarikurkcu C.; Tepe B.
In this study, we aimed to evaluate the phenolic composition, antioxidant, and enzyme inhibitory activities of ethanol and water extracts of Chenopodium botrys L. In the ethanol extract, the amounts of flavonoids, saponins, and condensed tannins were found to be higher than those of the water extract (4.54 mg of rutin equivalent (RE) per g of dry plant, 25.45 mg of quillaja equivalent (QAE) per g of dry plant, and 59.20 mg of catechin equivalent (CE) per g of dry plant, respectively). On the other hand, a total phenolic assay showed a superiority of the water extract (3.85 mg of gallic acid equivalent (GAE) per g of dry plant). The extracts were also subjected to screening for the quantification of selected compounds. Among the compounds, benzoic acid was found to be the most abundant one in the extracts (59.93 and 2974.24 μg per g of dry plant, respectively). In general, antioxidant activity assays showed the superiority of the water extract. C. botrys extracts were also evaluated for their inhibitory activities on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, α-amylase, and α-glucosidase. The water extract exhibited the highest inhibitory activity on AChE, tyrosinase, α-amylase, and α-glucosidase (113.69 μg of galantine equivalent (GALAE) per g of dry plant, 165.56 μg of kojic acid equivalent (KAE) per g of dry plant, 7.16 mg of acarbose equivalent (ACE) per g of dry plant, and 6.47 mg of ACE per g of dry plant, respectively). On the other hand, BChE inhibitory activity of the ethanol extract was found to be higher than that of the water extract (60.90 μg of GALAE per g of dry plant). According to the results of the antioxidant and enzyme inhibitory activity assays, C. botrys may have the potential to prevent diseases associated with oxidative stress and to prevent AD, pigmentation diseases, hyperglycaemia and its associated complications. © The Royal Society of Chemistry 2016.
Surface modification of CdSeS nanocrystals for polymer hybrid solar cells
(Royal Society of Chemistry, 2016) Erdogan A.; Karakaya C.; Gonce M.K.; Buyukcelebi S.; Yenel E.; Kara K.; Ozcivan A.N.; Can M.; Kus M.; Demic S.
We report the synthesis of fluorene-carbazole derivatives as capping agents for CdSeS nanocrystals and present their performance in polymer hybrid solar cells. CdSeS nanocrystals and different ligands consisting of fluorene and carbazole units were synthesized and characterized. Both oleic acid and pyridine capped CdSeS nanocrystals were used as reference materials in polymer hybrid solar cells. We observed that our synthesized materials show better efficiencies depending on their structures. In comparison with the reference cells consisting of pyridine capped CdSeS nanocrystals, ligand capped CdSeS shows better efficiency due to electron withdrawing and accepting groups in its structure. The reason behind the superiority of our ligands compared to the reference pyridine is the donor and/or acceptor based compatibility of the combined structures and effective surface modification as well. © 2016 The Royal Society of Chemistry.
Phenolic content, antioxidant and enzyme inhibitory capacity of two: Trametes species
(Royal Society of Chemistry, 2016) Zengin G.; Karanfil A.; Uren M.C.; Kocak M.S.; Sarikurkcu C.; Gungor H.; Nancy Picot C.M.; Mahomoodally M.F.
The phenolic composition, antioxidant and enzyme inhibitory activities of methanolic and water extracts of Trametes gibbosa (TG) and Trametes hirsuta (TH) were characterised for the first time. Reversed-phase high-performance liquid chromatography (RP-HPLC) analysis revealed that TG and TH methanolic extracts contained (+)-catechin, chlorogenic acid and caffeic acid. Methanolic extracts of TG and TH showed significantly (p < 0.05) high inhibition rates on acetyl (1.87 and 1.60 mg galantamine equivalents (GALAEs) per g extract respectively) and butyryl cholinesterase (1.71 and 1.90 mg GALAEs per g extract respectively). Low and insignificant inhibition was observed against α-amylase. α-Glucosidase inhibitory activity of TG (0.93 mmol acarbose equivalents (ACEs) per g extract) and TH (1.18 mmol ACEs per g extract) methanolic extracts were significantly (p < 0.05) high. Methanolic extract of TG (16.85 ± 0.29 TEs per g extract) and TH (13.86 ± 0.03 mg TEs per g extract) showed the most effective cupric reducing power. This study tends to support the potential use of these mushrooms species for designing new functional food formulations. © 2016 The Royal Society of Chemistry.
Comparative study of the intermolecular dynamics of imidazolium-based ionic liquids with linear and branched alkyl chains: OHD-RIKES measurements
(Royal Society of Chemistry, 2017) Xue L.; Bardak F.; Tamas G.; Quitevis E.L.
This article describes a comparative study of the low-frequency (0-450 cm-1) Kerr spectra of the branched 1-(iso-alkyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([(N - 2)mCN-1C1im][NTf2] with N = 3-7) ionic liquids (ILs) and that of the linear 1-(n-alkyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([CNC1im][NTf2] with N = 2-7) ILs. The spectra were obtained by use of femtosecond optical heterodyne-detected Raman-induced Kerr effect spectroscopy (OHD-RIKES). The intermolecular spectrum of a branched IL is similar to that of a linear IL that is of the same alkyl chain length rather than of the same number of carbon atoms in the alkyl chain. This similarity and the lack of a correlation of the first spectral moments and widths of the intermolecular spectra with chain length is mainly attributed to the increase in the dispersion contribution to the total molar cohesive energy being compensated by stretching of the ionic network due to the increasing size of the nonpolar domains, which is dependent only on the length of the alkyl chain. © the Owner Societies 2017.
Does a course on the history and philosophy of chemistry have any effect on prospective chemistry teachers' perceptions? the case of chemistry and the chemist
(Royal Society of Chemistry, 2017) Sendur G.; Polat M.; Kazanci C.
The creative comparisons prospective chemistry teachers make about "chemistry" and the "chemist" may reflect how they perceive these concepts. In this sense, it seems important to determine which creative comparisons prospective teachers make with respect to these and how these can change after the history of chemistry is treated in the classroom. This study seeks to investigate the impact of the basic History and Philosophy of Chemistry course on prospective chemistry teachers' perceptions towards chemistry and the chemist. The study was conducted during the 2012-2013 academic year at a state university in Turkey with 38 prospective chemistry teachers. A creative comparisons questionnaire and semi-structured interviews were used as data collection instruments in the study. This questionnaire was administered to the prospective teachers in the form of a pre-test, post-test, and retention test. Results of the analysis showed that the prospective teachers produced creative comparisons related to chemistry in the pre-test that mostly relied on their own experiences and observations, but that in the post-test and retention test, their comparisons mostly contained references to the role of chemistry in daily life, its development, and its facilitating aspects. Similarly, it was observed that in the pre-test, the prospective teachers made creative comparisons regarding the chemist that related mostly to the laboratory, but that the post-test and retention test rather contained the aspects of chemists as researchers, meticulous persons, facilitators and managers. Also, 18 prospective teachers were engaged in interviews to understand their prior knowledge about chemistry and the chemist, as well as the reasons for the changes in their creative comparisons. The results of the interviews indicated that a large majority of the prospective teachers were able to fully reflect on their inadequacy about their previous knowledge about "chemistry" and "chemist," and it was seen that they could explain the reason they changed their creative comparisons as an outcome of the History and Philosophy of Chemistry course. In the light of these results, it can be said that the History and Philosophy of Chemistry course may help prospective chemistry teachers in their perceptions about both chemistry and the chemist and may add depth to their knowledge. © 2017 The Royal Society of Chemistry.
Photoluminescence, radioluminescence and thermoluminescence properties of Eu3+ doped cadmium tantalate phosphor
(Royal Society of Chemistry, 2018) Ilhan M.; Keskin I.Ç.
For investigate spectroscopic properties, Eu3+ doped columbite type CdTa2O6 phosphors were synthesized using the solid state reaction method. The synthesized ceramic phosphors were investigated by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), photoluminescence (PL), radioluminescence (RL) and thermoluminescence (TL) analyses. CdTa2O6:Eu3+ phosphors exhibited emissions at 591.8 nm and 612.1 nm because of the characteristic band transitions of the Eu3+ ion. Phosphor emission increased with increasing Eu3+ ion dopant up to 1.5 mol%, and then decreased owing to concentration quenching. The decay times decreased with increasing Eu3+ dopant, while they were varied from 711 to 534 μm. The scintillation emissions of Eu3+ doped samples from the UV to near-IR spectral region were monitored by RL measurements. The high RL emission may be attributed to the good scintillation property of phosphor. TL glow curves were monitored for different Eu3+ concentrations in the range of 50 °C to 400 °C at a heating rate of 2 °C s-1, after being irradiated under short-wave UV light (254 nm). © 2018 The Royal Society of Chemistry.
The synergistic effect of Er3+and Ho3+on temporal color tuning of upconversion emission in a glass host: Via a facile excitation modulation technique for anti-counterfeiting applications
(Royal Society of Chemistry, 2020) Erol E.; Kibrisli O.; Vahedigharehchopogh N.; Çelikbilek Ersundu M.; Ersundu A.E.
Lanthanide-doped upconversion luminescent materials are highly promising for diverse applications, e.g., solid-state lighting, volumetric displays, and anti-counterfeiting, owing to their unique optical feature of color-tunable emission under near-infrared excitation. Hence, in this study, emission color tuning of Er3+/Ho3+ ions in a fixed glass host is investigated via a facile excitation modulation technique. The upconversion emission color from green to yellowish is tuned successfully by regulating the frequency of the irradiation source. The population and depopulation rates of related transitions are investigated through time-resolved photoluminescence and Judd-Ofelt analysis in order to elucidate the proposed mechanism of color tuning. Upconversion quantum yield values are measured in the range of 0.12 to 0.17% for a better comparison of the emission properties. Additionally, thermal, and structural properties are investigated to reveal the favorable properties of the selected tellurite glass host. Ultimately, several patterns are designed and constructed by a screen-printing technique using powdered glass to demonstrate its suitability as a multicolor imaging method for anti-counterfeiting applications. The temporal color tuning of upconversion emission via a facile excitation modulation technique in a glass host clearly indicates that the proposed Er3+/Ho3+ co-doped glasses can be potentially applied in the state-of-the-art technologies, especially for anticounterfeiting purposes. © the Owner Societies.
Analysis of Judd-Ofelt parameters and radioluminescence results of SrNb2O6:Dy3+phosphors synthesizedviamolten salt method
(Royal Society of Chemistry, 2020) İlhan M.; Keskin İ.Ç.
In this work, Dy3+-doped SrNb2O6phosphors were fabricated by the molten salt process, which avoids high sintering temperatures, prolonged reaction time and poor compositional homogeneity. All samples crystallized to the orthorhombic columbite structure with space group,P21/c, while a rod-like morphology was observed by scanning electron microscopy (SEM). PL (photoluminescence) and RL (radioluminescence) spectra of SrNb2O6:Dy3+exhibited a strong blue emission peak at 576.0 nm related to4F9/2→6H15/2transition of Dy. The high RL emission of the4F9/2→6H15/2(electric dipole) transition upon X-ray-induced excitation led to a decrease in Dy3+local environmental symmetry. The Judd-Ofelt (J-O) theory was applied to the PL excitation spectra for the calculation of optical data such asΩ2,Ω4, andΩ6parameters, radiative transition probability (Ar), branching ratios (β,βexp) and stimulated emission cross-section (σe). The quantum efficiencies (ηQE) varied between 35.47 and 31.93%, which are compatible with theoretical quantum efficiencies based on the Einstein relation. The CIE chromaticity coordinates (x,y) and CCT (correlated color temperature) parameter for 3 mol% phosphor were defined (0.385, 0.432) and 4209 K, respectively. © the Owner Societies 2020.
Judd-Ofelt parameters and X-ray irradiation results of MNb2O6:Eu3+(M = Sr, Cd, Ni) phosphors synthesizedviaa molten salt method
(Royal Society of Chemistry, 2021) İlhan M.; Ekmekçi M.K.; Keskin İ.Ç.
Trivalent Eu-activated MNb2O6(M = Sr, Cd, Ni) ceramic phosphors were produced using the molten salt route, which involves a low sintering temperature and provides improved homogeneity. The photoluminescence (PL) and radioluminescence (RL) spectra of phosphors exhibited characteristic Eu3+emissions with5F0→7Fjtransitions, and strong peaks occurred at the5D0→7F2transition. The PL and RL emissions of SrNb2O6:Eu3+decreased over 3 mol%, while both emissions for CdNb2O6:Eu3+and NiNb2O6:Eu3+increased with increasing Eu3+concentration. The spectral properties of phosphors were evaluated by determining Judd-Ofelt intensity parameters (Ω2,Ω4) from the PL emission spectrum. The quantum efficiencies (ηQE%) of MNb2O6:Eu3+(M = Sr, Cd, Ni) phosphors with the highest emission were found as 61.87%, 41.89%, and 11.87% respectively. Bandwidths (σe× Δλeff) and optical gains (σe×τ) of MNb2O6:Eu3+(M = Sr, Cd, Ni) phosphors with highest emissions were found as follows; 24.182 × 10−28, 28.674 × 10−28, 38.647 × 10−28cm3and 20.441 × 10−25, 13.790 × 10−25, 3.987 × 10−25cm2s, respectively, corresponding to the5D0→7F2transition. © The Royal Society of Chemistry 2021.
A straightforward approach for high-end anti-counterfeiting applications based on NIR laser-driven lanthanide doped luminescent glasses
(Royal Society of Chemistry, 2021) Vahedigharehchopogh N.; Kıbrıslı O.; Erol E.; Çelikbilek Ersundu M.; Ersundu A.E.
The increase in forgery in documents and authentic products has motivated the search for new high-end anti-counterfeiting strategies. Various chameleon-like luminescent materials such as up-conversion nanoparticles or perovskite nanocrystals have drawn attention due to their favorable properties. However, these materials are fabricated through complex processes and often suffer from system instability. In this work a facile and inexpensive approach for color tuning of thermally and chemically stable Ho3+/Tm3+/Yb3+doped tellurite glasses is experimentally demonstrated for the first time. The emission band ratios are successfully manipulated by focusing/defocusing the NIR laser beam irradiating the glass samples. Impressive up-conversion quantum yield values up to 4.56% are obtained along with high lifetime values from ∼100 to 200 microseconds. As proof of concept, a series of anti-counterfeiting patterns are created using the screen-printing method and different emission colors are observed by easily changing the distance between the sample and the laser focal point. The applicability of the presented strategy along with the remarkable properties of the studied lanthanide doped glasses proves the capability of these materials to be used in anti-counterfeiting applications. © The Royal Society of Chemistry 2021.
Recyclability of CsPbBr3 quantum dot glass nanocomposites for their long-standing use in white LEDs
(Royal Society of Chemistry, 2022) Vahedigharehchopogh N.; Erol E.; Kıbrıslı O.; Genç A.; Çelikbilek Ersundu M.; Ersundu A.E.
The embedding of CsPbBr3 perovskite quantum dots (PQDs) in an inorganic glass matrix not only protects them against chemical, thermal, and photodegradation but also provides an effective strategy to isolate toxic elements such as Pb from the environment for a long period of time. Herein, the recyclability of glass is another important feature that contributes to environmental sustainability. Hence, effective and efficient recycling technologies are needed for the widespread use of PQD glass nanocomposites (GNCs) in many commercial applications. However, studies on the recyclability of CsPbBr3 PQD GNCs have not been conducted so far. Therefore, in this work, we investigate the structural, thermal, optical, and photoluminescence properties of recycled CsPbBr3 PQD GNCs to assess their suitability as long-standing and reusable luminescent materials. For this purpose, the recyclability of GNCs is checked by three repeated melt-quenching and subsequent heat-treatment processes. Although the color emission properties of GNCs under the same heat-treatment conditions show a slight variation after each recycling step, PQD GNCs almost retain their PLQY even after the last recycling step. Ultimately, a prototype white light-emitting diode is constructed by coupling recycled PQD GNCs and a commercial red phosphor on top of a blue LED chip showing high-performance with CIE color coordinates of x = 0.3228, y = 0.3470 and a CCT value of 5920 K. The findings of this work reveal that the recyclability of PQD GNCs holds great promise for a more sustainable technology. © 2022 The Royal Society of Chemistry.
Color tunable emission from Eu3+and Tm3+co-doped CsPbBr3quantum dot glass nanocomposites
(Royal Society of Chemistry, 2022) Erol E.; Kibrisli O.; Çelikbilek Ersundu M.; Ersundu A.E.
Cesium lead bromide (CsPbBr3) quantum dots (QDs) have shown great potential in the field of luminescent materials owing to their superior optical and electrical properties. However, instability and lack of multicolor emissions resulting from the intrinsic nature of CsPbBr3 QDs are still the major challenge for their commercialization. Herein, Eu3+ and Tm3+ co-doped CsPbBr3 QD glass nanocomposites (GNCs) are successfully synthesized via traditional melt-quenching followed by a heat-treatment route to obtain tunable emission in a durable host material. Tm3+ ions are doped to blue-shift the main emission peak of CsPbBr3 QDs, while Eu3+ ions are incorporated to compensate for the red deficiency. Accordingly, a tunable color emission spanning the entire visible spectrum is achieved from GNCs with a fixed composition. The incorporation of Eu3+ and Tm3+ ions promotes the crystallization of CsPbBr3 QDs in the glass host resulting in ∼100% photoluminescence quantum yield (PLQY) using a dilution method. The selected glass host has also been proven to effectively protect CsPbBr3 QDs against chemical, thermal and photo degradation. Interestingly, the selected Eu3+/Tm3+ co-doped CsPbBr3 QD GNC shows warm-white light with a low color temperature of 3692 K without utilizing any commercial phosphors. This indicates that the produced GNCs have the potential to be used as light convertor materials in multi-color LED or warm white LED applications due to their robust stability and extremely pure and tunable emission colors. © 2022 the Owner Societies.
The coupling of blue emitting carbon dots with Eu3+/Tb3+ co-doped luminescent glasses for utilization in white light emitting diodes
(Royal Society of Chemistry, 2023) Korkmaz U.; Özlem B.; Erol E.; Alas M.I.; Genç Altürk R.; Çelikbilek Ersundu M.; Ersundu A.E.
Lanthanide-doped luminescent glasses have attracted tremendous attention in modern optoelectronic applications, especially for solid-state white light-emitting diodes (WLEDs). Eu3+/Tb3+ co-doped luminescent glasses are well-known to emit intense yellowish-orange light resulting from the energy transfer from green-emitting sensitizer Tb3+ ions to red-emitting activator Eu3+ ions. Obtaining highly efficient blue light from lanthanide ions remains a challenge due to their weak down-converted emission. In this work, we attempt to use the unique characteristics of blue-emitting carbon dots (BCDs), i.e., a broad emission spectrum, ease of synthesis, and high stability, to compensate for this blue light deficiency problem. Correspondingly, a new strategy is proposed by coupling BCDs with Eu3+/Tb3+ co-doped glasses for their potential utilization in WLEDs. Hence, Eu3+/Tb3+ co-doped glasses are prepared in different thicknesses, i.e., 0.8, 1, and 1.5 mm, via the conventional melt-quenching method and subsequently spin-coated with BCDs to achieve adjustable photoluminescence quantum yield (PLQY) values. Ultimately, a proof-of-concept WLED is prepared using a 0.8 mm thick BCD-coated Eu3+/Tb3+ co-doped luminescent glass exhibiting outstanding luminescence performance with a CRI value of 92, a CCT of 4683 K, color coordinates of (x = 0.3299, y = 0.3421), a satisfying PLQY value of 55.58%, and a corresponding LER value of 316 lm W−1 under the excitation of a 375 nm UV LED. BCD-coated Eu3+/Tb3+ co-doped luminescent glasses show excellent stability against photobleaching, temperature variations, and humidity. The findings of this work indicate that the coupling of BCDs with Eu3+/Tb3+ co-doped luminescent glasses holds great potential as a substitute for traditional solid-state lighting sources. © 2023 The Royal Society of Chemistry.
Exploring the effect of boron on the grain morphology change and spectral properties of Eu3+ activated barium tantalate phosphor
(Royal Society of Chemistry, 2024) İlhan M.; Güleryüz L.F.; Katı M.İ.
The effect of the grain morphology on the photoluminescence, charge transfer band, and decay properties was investigated by xEu3+, yB3+ (x = 10 mol%, y = 0, 5, 15, 30, 50, 70, and 100 mol%) co-doped BaTa2O6 ceramics fabricated by solid-state reaction. X-ray diffractions of the samples showed that the single-phase structure persisted up to 100 mol% and there was an improvement in crystallinity with increasing B3+ concentration. SEM micrographs of the Eu3+, B3+ co-doped grains showed that the flux effect of boron promotes grain growth and elongated grain shape. The PL emissions of the BaTa2O6:xEu3+, yB3+ co-doped phosphors increased up to 100 mol% B3+ concentration, and there was an increase in the intensities of the CTB energy 5D0 → 7F1 transition. The increase in PL may be attributed to the increased grain size leading to a decrease in the surface area (SA)/volume (vol) ratio with increasing B3+ concentration, as well as the improvement in crystallinity. However, the decrease in asymmetry ratio was related to the occupation of centrosymmetric (B) sites and the transformation from a rounded/irregular-like to an elongated/rod-like grain shape which has an increasing effect on the SA/vol ratio. The decreasing trend of the Judd-Ofelt parameters (Ω2, and Ω4) with the increase in boron was related to a high local symmetry of Eu3+ sites, and an increase in the electron density of the surrounding ligands, respectively. The increase in boron led to longer decays in the observed lifetime with bi-exponential characteristics. The CIE diagram and UV lamp photographs of the phosphors showed a color transition from red to orange associated with the increasing magnetic dipole transition. This study may provide an alternative perspective and new strategies to describe the control of grain morphology and luminescence concerning RE-doped phosphors. © 2024 The Royal Society of Chemistry.
Interfacial synergy of pre-lithiation silicon anodes and GNP/MnO2/S cathodes for lithium polysulfides in silicon-sulfur batteries studied via DFT
(Royal Society of Chemistry, 2025) Aslfattahi N.; Kiai M.S.; Karatas D.; Baydogan N.; Samylingam L.; Kadirgama K.; Kok C.K.
The development of innovative electrodes with outstanding high-rate cycling performance for the next generation of sulfur-based batteries has emerged as a key area of research. This study presents a straightforward approach for designing silicon/graphene nanoplates as an anode material using a one-step hydrothermal process. Additionally, to reduce the shuttle effect, the GNP/MnO2/S cathode is investigated. In this study, MnO2 particles are grown in situ on the surface of the GNP. The pre-lithiation Si/GNP anode and the MnO2/GNP/S and GNP/S cathodes are evaluated at a current density of 1000 mA g−1. The findings reveal an impressive capacity retention of 1048 mA h g−1 after 200 cycles, indicating remarkable cycling performance for the cell with the pre-lithiation Si/GNP anode and the MnO2/GNP/S cathode. The capacity retention observed in thicker electrodes highlights the synergistic effect of the effective chemical absorption of lithium polysulfides by MnO2/GNP/S when used as sulfur hosts. Additionally, DFT calculations suggest that MnO2 has a significant tendency to adhere to the surface of polysulfides, aligning well with our findings regarding cycle performance, rate performance, and discharge capacity. The novel electrode configuration introduced in this study provides a novel pathway for the large-scale production of high-performance pre-lithiation Si-S batteries. © 2025 The Royal Society of Chemistry.

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