| 1. |
- Belay Ibrahim, Kassa, et al.
(författare)
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Emerging 2D materials beyond mxenes and TMDs: Transition metal carbo-chalcogenides
- 2024
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Ingår i: Progress in Materials Science. - : Elsevier Ltd. - 0079-6425 .- 1873-2208. ; 144
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Forskningsöversikt (refereegranskat)abstract
- Interestingly, it opens the door for the development of the 2D materials family, which includes different classes of 2D materials. Among them, transition metal dichalcogenides (TMDs) and transition metal carbide MXenes (TMCs) have emerged. TMDs have unique layered structures, low cost, and are composed of earth abundant elements, but their poor electronic conductivity, poor cyclic stability, their structural and morphological changes during electrochemical measurements hinder their practical use. Recently, TMC MXenes have garnered attention in the 2D material world, but the issue of restacking and aggregation limits their direct use in large-scale energy conversion and storage. To address these challenges, hetero structures based on conductive TMCs MXenes and electrochemically active TMDs have emerged as a promising solution. However, understanding the solid/solid interface in heterostructured materials remains a challenge. To tackle this, 2D single component crystals with high capacity, low diffusion barrier, and good electronic conductivity are highly sought. The emergence of transition metal carbo-chalcogenides (TMCCs) has provided a potential solution, as these 2D nanosheets consist of TM2X2C, where TM represents transition metal, X is either S or Se, and C atom. This new class of 2D materials serves as a remedy by avoiding the challenges related to solid/solid interfaces often encountered in heterostructures. This review focuses on the latest developments in TMCCs, including their synthetic strategies, surface/interface engineering, and potential application in batteries, water splitting, and other electro-catalytic processes. The challenges and future perspectives of the design of TMCCs for electrochemical energy conversion and storage are also discussed.
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| 2. |
- Enrichi, Francesco, et al.
(författare)
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Structural and optical properties of Eu3+-doped sol-gel silica-soda glasses
- 2024
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Ingår i: The European Physical Journal Plus. - : Springer Nature. - 2190-5444. ; 139:4
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Tidskriftsartikel (refereegranskat)abstract
- Rare earths (REs) incorporated in glasses, mostly in the form of RE3+ ions, have several applications such as lasers and optical amplifiers, spectral conversion layers for solar cells, light emitters and sensors. In this context, both the composition and the structural properties of the glass, as well as the dopant concentration play an important role in determining the optical properties and the efficiency of the system. Usually, the concentration of REs is small, below 1 at%, to avoid clustering and optical quenching. In this paper, we report the case of sol-gel Eu-doped silica-soda glass films. The addition of soda to silica can reduce RE clustering and precipitation, according to molecular dynamic simulations, but brings structural instabilities to the network. Here, sodium was varied from 10 to 30 at% and Eu from 0 to 8 at%. It was shown that Eu plays a significant role in the stabilization of the matrix, improving the transparency, the refractive index and the thickness of the films. The increase of Eu concentration provides a decrease of site symmetry and an increase of quantum efficiency (QY), reaching 71% for the highest 8 at% Eu doping, with remarkable absence of concentration quenching.
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| 3. |
- Enrichi, Francesco, et al.
(författare)
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Structural and optical properties of Eu3+-doped sol–gel silica–soda glasses
- 2024
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Ingår i: The European Physical Journal Plus. - : Springer Nature. - 2190-5444. ; 139:4
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Tidskriftsartikel (refereegranskat)abstract
- Rare earths (REs) incorporated in glasses, mostly in the form of RE3+ ions, have several applications such as lasers and optical amplifiers, spectral conversion layers for solar cells, light emitters and sensors. In this context, both the composition and the structural properties of the glass, as well as the dopant concentration play an important role in determining the optical properties and the efficiency of the system. Usually, the concentration of REs is small, below 1 at%, to avoid clustering and optical quenching. In this paper, we report the case of sol–gel Eu-doped silica–soda glass films. The addition of soda to silica can reduce RE clustering and precipitation, according to molecular dynamic simulations, but brings structural instabilities to the network. Here, sodium was varied from 10 to 30 at% and Eu from 0 to 8 at%. It was shown that Eu plays a significant role in the stabilization of the matrix, improving the transparency, the refractive index and the thickness of the films. The increase of Eu concentration provides a decrease of site symmetry and an increase of quantum efficiency (QY), reaching 71% for the highest 8 at% Eu doping, with remarkable absence of concentration quenching.
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| 4. |
- Feltrin, Ana Carolina
(författare)
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Entropy-stabilized transition metal diborides for high-temperature applications
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ultra-high temperature ceramics (UHTCs) are on the cutting edge as structural or protective materials that can withstand extreme environments such as hypersonic vehicles, nuclear reactors, and advanced turbine engines. These materials stand out for their melting temperatures above 2500 °C, high chemical stability, and retained mechanical resistance at temperatures higher than 1650 °C. Introducing entropy-stabilization into multicomponent ceramics has attracted interest in their properties over a broad range of UHTC compositions. Entropy plays a dominant role in stabilizing single-phase multicomponent materials, offering new pathways for synthesis and enabling the tailoring of properties. The promising properties are mainly attributed to their compositional complexity, lattice distortion and atomic-level disorder.In this thesis, by screening potential high-entropy ceramic candidates via ab initio calculations, we identified six potential high-entropy ceramics compositions containing Li, Ti, V, Zr, Nb, and Hf. Subsequently, we have focused on and covered the design, synthesis, and high-temperature oxidation and ablation properties of the entropy-stabilized (Ti0.25V0.25Zr0.25Hf0.25)B2. The diboride synthesis using Spark Plasma Sintering (SPS) resulted in a dual-phase (Ti0.25V0.25Zr0.25Hf0.25)B2, composed of Hf-Zr-rich and Ti-V-rich hexagonal phases. Upon thermal annealing, the dual-phase diboride transformed into a single-phase entropy-stabilized diboride, exhibiting superior mechanical properties compared to the dual-phase diboride. The oxidation mechanisms were the same for the dual- and single-phase diborides; however, the entropy-stabilized diboride outperformed the dual-phase diboride in terms of oxidation resistance. The improved mechanical and oxidation properties were attributed to the lattice distortion, high-entropy, and sluggish diffusion effects. UHTC coatings are usually applied in carbon materials to improve their service life in harsh environments. Due to the improved oxidation performance of the entropy-stabilized diboride, single-phase (Ti0.25V0.25Zr0.25Hf0.25)B2 was produced as a coating on graphite by Spark Plasma Sintering (SPS) and its resistance to ablation was evaluated. The mechanical resistance of the entropy-stabilized coating at high temperatures was attributed to its low thermal conductivity and the efficient heat dissipation of the coating-substrate pair. The (Ti0.25V0.25Zr0.25Hf0.25)B2 coating was considered an efficient thermal barrier with high resistance to intense heat fluxes. Furthermore, manufacturing of the (Hf0.25Zr0.25Ti0.25V0.25)B2-B4C by pressureless and less energy intensive Ultra-fast High-temperature Sintering (UHS) method was investigated for entropy-stabilization. Single-phase formation happened before the full densification of the composite, and the B4C sintering aid promoted the densification of the (Hf0.25Zr0.25Ti0.25V0.25)B2 with a minor eutectic phase. Overall, the results obtained by this work contribute to the growing body of knowledge surrounding entropy-stabilized ceramics, their design and fabrication through computational and experimental methods, and their potential applications in engineering components at high temperatures. These findings pave the way for new paths to be followed in the entropy-stabilized materials realm.
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| 5. |
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| 6. |
- Hussain, Muzammil, et al.
(författare)
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Enhanced Solar Water Desalination by CuCo2S4-decorated Carbon Foam Derived from Waste Plastics
- 2024
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Ingår i: Chemical Research in Chinese Universities. - : Springer Nature. - 1005-9040 .- 2210-3171. ; 40, s. 548-555
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Tidskriftsartikel (refereegranskat)abstract
- Interfacial solar desalination is an emerging technology for freshwater production, but the finding of novel solar evaporators is still challenging. In the present research, graphitic carbon foam (CF) was synthesized from the upcycling of waste plastic polyethylene terephthalate (PET) waste bottles functionalized with carrollite CuCo2S4 as a photothermal layer. Analytical characterization [X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS)] confirms the functionalization of carrollite CuCo2S4 on graphitic carbon foam. The UV-Vis spectroscopy analysis showed an enhanced optical absorption in the UV-Vis-near IR region (>96%) for functionalized CuCo2S4-CF foam compared to carbon foam (67%). The interfacial solar desalination experiment presented a significantly enhanced evaporation rate of 2.4 kg·m−2·h−1 for CuCo2S4-CF compared to that of CF (1.60 kg·m−2·h−1) and that of CuCo2S4 (1.60 kg·m−2·h−1). The obtained results proved that the newly synthesized CuCo2S4-CF from the upcycled plastic into new material for the photothermal desalination process can enhance the practice of a circular economy to produce fresh water.
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| 7. |
- Kumar, Pankaj, et al.
(författare)
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All-Inorganic Hydrothermally Processed Semitransparent Sb2S3 Solar Cells with CuSCN as the Hole Transport Layer
- 2024
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society. - 2574-0962. ; 7:4, s. 1421-1432
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Tidskriftsartikel (refereegranskat)abstract
- Published by American Chemical Society.An inorganic wide-bandgap hole transport layer (HTL), copper(I) thiocyanate (CuSCN), is employed in inorganic planar hydrothermally deposited Sb2S3 solar cells. With excellent hole transport properties and uniform compact morphology, the solution-processed CuSCN layer suppresses the leakage current and improves charge selectivity in an n-i-p-type solar cell structure. The device without the HTL (FTO/CdS/Sb2S3/Au) delivers a modest power conversion efficiency (PCE) of 1.54%, which increases to 2.46% with the introduction of CuSCN (FTO/CdS/Sb2S3/CuSCN/Au). This PCE is a significant improvement compared with the previous reports of planar Sb2S3 solar cells employing CuSCN. CuSCN is therefore a promising alternative to expensive and inherently unstable organic HTLs. In addition, CuSCN makes an excellent optically transparent (with average transmittance >90% in the visible region) and shunt-blocking HTL layer in pinhole-prone ultrathin(<100 nm) semitransparent absorber layers grown by green and facile hydrothermal deposition. A semitransparent device is fabricated using an ultrathin Au layer (∼10 nm) with a PCE of 2.13% and an average visible transmittance of 13.7%.
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| 8. |
- Li, Weihua, et al.
(författare)
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Controllable and large-scale synthesis of carbon quantum dots for efficient solid-state optical devices
- 2024
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Ingår i: Nano Energy. - : Elsevier Ltd. - 2211-2855 .- 2211-3282. ; 122
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Tidskriftsartikel (refereegranskat)abstract
- Carbon quantum dots (C-dots) showed excellent structure-tunable optical properties, mainly composed of carbon, nitrogen and oxygen. They have been used for various types of solid-state optical devices. Due to the photoluminescence quenching caused by aggregation, it is a challenge to produce high quantum yield and large Stokes shift C-dots via controllable and simple approaches. In this work, we demonstrated a microwave assisted heating approach for the high-quality C-dots production with ten grams scale per batch in less than 4 min. The addition of metal cation promoted the formation of the foam-structure by forming carboxyl-metal-amine complex, enabling the spatial confined growth of the C-dots in a solid-state, contributing to the high quantum yield (QY) of 73% with a Stokes shift of 0.65 eV. By tuning the structure of the C-dots, excitation dependent and independent photoluminescent (PL) behavior were achieved because of the formation of the different types of energy states evidenced by transient PL and femtosecond transient absorption spectroscopy. These optical properties enable the C-dots to be successfully integrated in luminescent solar concentrators (LSCs), having an external optical efficiency of 3.0% and a power conversion efficiency of 1.3% (225 cm2) and an excitation-dependent high-level anticounterfeiting fluorescent code, showing a great potential for solid-state optical system.
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| 9. |
- Liccardo, Letizia, et al.
(författare)
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Surface Defect Engineered Nano-Cu/TiO2 Photocatalysts for Hydrogen Production
- 2024
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Ingår i: Advanced Sustainable Systems. - : John Wiley & Sons. - 2366-7486. ; 8:3
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Tidskriftsartikel (refereegranskat)abstract
- Surface defects engineered nano-Cu/TiO2 photocatalysts are synthesized through an easy and cost-effective microwave-assisted hydrothermal synthesis, mixing commercial P25 titania (TiO2) and oxalic acid (Ox), followed by 2.0 wt% Cu co-catalyst (labeled as Cu2.0) loading through in situ photodeposition during reaction. The hydrothermal treatment does not affect the catalyst crystalline structure, morphology, nor the surface area. However, depending on the Ox/TiO2 molar ratio used an influence on the optical properties and on the reactivity of the system is detected. The presence of surface defects leads to intraband states formation between valence band and conduction band of bare titania, inducing an important enhancement in the photoactivity. Thus, Cu2.0/gOx/P25 200 (where g is the weight of Ox and 200 the temperature in Celsius degrees used during the synthesis) have been successfully tested as efficient photocatalysts for hydrogen production through methanol (MeOH) reforming under UV light in a MeOH/ H2O solution (10% v/v) by fluxing the system with N2, showing an increased reactivity compared to the bare Cu2.0/P25 system.
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| 10. |
- Lushaj, Edlind, et al.
(författare)
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Highly Efficient Solar-Light-Driven Photodegradation of Metronidazole by Nickel Hexacyanoferrate Nanocubes Showing Enhanced Catalytic Performances
- 2024
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Ingår i: Small Methods. - : John Wiley & Sons. - 2366-9608.
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Tidskriftsartikel (refereegranskat)abstract
- Environmental pollution is a complex problem that threatens the health and life of animal and plant ecosystems on the planet. In this respect, the scientific community faces increasingly challenging tasks in designing novel materials with beneficial properties to address this issue. This study describes a simple yet effective synthetic protocol to obtain nickel hexacyanoferrate (Ni-HCF) nanocubes as a suitable photocatalyst, which can enable an efficient photodegradation of hazardous anthropogenic organic contaminants in water, such as antibiotics. Ni-HCF nanocubes are fully characterized and their optical and electrochemical properties are investigated. Preliminary tests are also carried out to photocatalytically remove metronidazole (MDZ), an antibiotic that is difficult to degrade and has become a common contaminant as it is widely used to treat infections caused by anaerobic microorganisms. Under simulated solar light, Ni-HCF displays substantial photocatalytic activity, degrading 94.3% of MDZ in 6 h. The remarkable performance of Ni-HCF nanocubes is attributeto a higher ability to separate charge carriers and to a lower resistance toward charge transfer, as confirmed by the electrochemical characterization. These achievements highlight the possibility of combining the performance of earth-abundant catalysts with a renewable energy source for environmental remediation, thus meeting the requirements for sustainable development.
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| 11. |
- Pankratova, Daria, et al.
(författare)
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Enhanced Thermoelectric Properties by Embedding Fe Nanoparticles into CrN Films for Energy Harvesting Applications
- 2024
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society. - 2574-0970. ; 7:3, s. 3428-3435
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured materials and nanocomposites have shown great promise for improving the efficiency of thermoelectric materials. Herein, Fe nanoparticles were imbedded into a CrN matrix by combining two physical vapor deposition approaches, namely, high-power impulse magnetron sputtering and a nanoparticle gun. The combination of these techniques allowed the formation of nanocomposites in which the Fe nanoparticles remained intact without intermixing with the matrix. The electrical and thermal transport properties of the nanocomposites were investigated and compared to those of a monolithic CrN film. The measured thermoelectric properties revealed an increase in the Seebeck coefficient, with a decrease of hall carrier concentration and an increase of the electron mobility, which could be explained by energy filtering by internal phases created at the NP/matrix interface. The thermal conductivity of the final nanocomposite was reduced from 4.8 W m-1 K-1 to a minimum of 3.0 W m-1 K-1. This study shows prospects for the nanocomposite synthesis process using nanoparticles and its use in improving the thermoelectric properties of coatings.
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| 12. |
- Sendeku, Marshet Getaye, et al.
(författare)
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Frontiers in Photoelectrochemical Catalysis: A Focus on Valuable Product Synthesis
- 2024
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Ingår i: Advanced Materials. - : John Wiley & Sons. - 0935-9648 .- 1521-4095. ; 36:21
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Forskningsöversikt (refereegranskat)abstract
- Photoelectrochemical (PEC) catalysis provides the most promising avenue for producing value-added chemicals and consumables from renewable precursors. Over the last decades, PEC catalysis, including reduction of renewable feedstock, oxidation of organics, and activation and functionalization of C─C and C─H bonds, are extensively investigated, opening new opportunities for employing the technology in upgrading readily available resources. However, several challenges still remain unsolved, hindering the commercialization of the process. This review offers an overview of PEC catalysis targeted at the synthesis of high-value chemicals from sustainable precursors. First, the fundamentals of evaluating PEC reactions in the context of value-added product synthesis at both anode and cathode are recalled. Then, the common photoelectrode fabrication methods that have been employed to produce thin-film photoelectrodes are highlighted. Next, the advancements are systematically reviewed and discussed in the PEC conversion of various feedstocks to produce highly valued chemicals. Finally, the challenges and prospects in the field are presented. This review aims at facilitating further development of PEC technology for upgrading several renewable precursors to value-added products and other pharmaceuticals.
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| 13. |
- Taranova, Anastasiia, et al.
(författare)
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Emerging Strategies to Achieve Interfacial Solar Water Evaporation Rate Greater than 3 kg·m-2·h-1 under One Sun Irradiation
- 2024
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Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 128:Part A
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Forskningsöversikt (refereegranskat)abstract
- Solar water evaporation is vital for addressing global water scarcity, particularly in regions with limited freshwater. Through the utilization of photothermal materials, solar water evaporation harnesses solar radiation to generate heat, which in turn accelerates the evaporation of water, producing clean drinking water. Subsequently, the vapor is condensed to produce fresh water, offering a sustainable solution to water scarcity. This research field has garnered immense scientific interest, with over six thousand publications. Reported solar absorber evaporation rates exceed 100 kg m−2 h−1 under one sun irradiation, far surpassing the theoretical limit of 1.47 kg m−2 h−1 achievable on two-dimensional absorber surfaces, assuming constant latent heat at 2444 J g−1. This review addresses this significant discrepancy in theoretical and practical values. A cut-off of 3 kg m−2 h−1 (under one sun irradiation) is considered to narrow focus, facilitating analysis of high-rate evaporators. Critical challenges and factors contributing to high evaporation rates are discussed, providing comprehensive insights into field advancements.
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| 14. |
- Taranova, Anastasiia, et al.
(författare)
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Nickel and Cobalt Selenite Hydrates as Broad Solar Absorbers for Enhanced Solar Water Evaporation
- 2024
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Ingår i: Solar RRL. - : John Wiley and Sons Inc. - 2367-198X.
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Tidskriftsartikel (refereegranskat)abstract
- Inorganic black materials possessing hydrophilicity are scarce but can be of great importance in areas such as solar water evaporation and solar steam generation. Herein, for the first time, transition-metal selenite hydrates (specifically, Earth-abundant metals Ni and Co) not only possess high solar absorbance (>96 %) in the solar spectral range (UV–vis–NIR) but also excellent hydrophilicity, which plays a key role in water transport in the solar steam generation. The hydrophilic behavior in selenite hydrates originates from trapped “water of hydration” inside its crystal lattice, which can easily form hydrogen bonds with other water molecules, facilitating water transport. Owing to the abovementioned properties, the studied selenite hydrates are tested for solar water evaporation, showing excellent water evaporation rates of 1.83 and 2.34 kg m−2 h−1 for nickel selenite hydrate and cobalt selenite hydrate, exceeding the theoretical limit of 1.47 kg m−2 h−1.
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| 15. |
- Taranova, Anastasiia, et al.
(författare)
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Temperature-Dependent Structural Properties of Nickel and Cobalt Selenite Hydrates as Solar Water Evaporators
- 2024
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Ingår i: Materials. - : Multidisciplinary Digital Publishing Institute (MDPI). - 1996-1944. ; 17:11
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Tidskriftsartikel (refereegranskat)abstract
- Solar water evaporation offers a promising solution to address global water scarcity, utilizing renewable energy for purification and desalination. Transition-metal selenite hydrates (specifically nickel and cobalt) have shown potential as solar absorbers with high evaporation rates of 1.83 and 2.34 kg∙m−2∙h−1, but the reported discrepancy in evaporation rate deserves further investigation. This investigation aims to clarify their thermal stability for applications and determine the underlying mechanisms responsible for the differences. Nickel and cobalt selenite hydrate compositions were synthesized and investigated via thermogravimetric analysis, X-ray diffraction, and Raman spectroscopy to assess their temperature-induced structural and compositional variations. The results reveal distinct phase transitions and structural alterations under various temperature conditions for these two photothermal materials, providing valuable insights into the factors influencing water transportation and evaporation rates.
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| 16. |
- Xia, Li, et al.
(författare)
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Simultaneous copper incorporation in core/shell-structured eco-friendly quantum dots for high-efficiency photoelectrochemical hydrogen evolution
- 2024
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Ingår i: Nano Energy. - : Elsevier Ltd. - 2211-2855 .- 2211-3282. ; 122
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Tidskriftsartikel (refereegranskat)abstract
- The rational design of elemental incorporation in colloidal eco-friendly core/shell quantum dots (QDs) holds the potential to synergistically tailor their electronic band structure and carrier kinetics for applications in forthcoming “green” and high-efficiency solar energy conversion. Herein, we have conducted simultaneous Cu incorporation in both the core and shell regions of environment-benign AgInSe (AISe)/ZnSe core/shell QDs to realize high-efficiency solar-driven photoelectrochemical (PEC) hydrogen evolution. It is verified that Cu incorporation in AISe core enables an upward shift in the position of the band edge relative to the ZnSe shell, which promoted the electron delocalization and extended the lifetime of exciton. Simultaneously, Cu incorporation in the ZnSe shell further results in the trapping of photoinduced holes from AISe core, leading to a decelerated recombination of carriers. The prepared Cu-AISe/ZnSe:Cu QDs with optimized optoelectronic properties have been successfully employed to fabricate QDs-PEC devices, delivering a maximum photocurrent density of 9.1 mA cm−2 under standard AM 1.5 G illumination (100 mW cm−2). Our findings indicate that synchronous elemental incorporation in eco-friendly core/shell QDs is a promising strategy to achieve future high-performance solar-to-hydrogen conversion systems.
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| 17. |
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| 18. |
- Ibrahim, Kassa Belay, et al.
(författare)
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Confinement Accelerates Water Oxidation Catalysis : Evidence from In Situ Studies
- 2023
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Ingår i: Small Methods. - : John Wiley & Sons. - 2366-9608. ; 7:10
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Tidskriftsartikel (refereegranskat)abstract
- Basic insight into the structural evolution of electrocatalysts under operating conditions is of substantial importance for designing water oxidation catalysts. The first-row transition metal-based catalysts present state-of-the-art oxygen evolution reaction (OER) performance under alkaline conditions. Apparently, confinement has become an exciting strategy to boost the performance of these catalysts. The van der Waals (vdW) gaps of transition metal dichalcogenides are acknowledged to serve as a suitable platform to confine the first-row transition metal catalysts. This study focuses on confining Ni(OH)2 nanoparticle in the vdW gaps of 2D exfoliated SnS2 (Ex-SnS2) to accelerate water oxidation and to guarantee long term durability in alkaline solutions. The trends in oxidation states of Ni are probed during OER catalysis. The in situ studies confirm that the confined system produces a favorable environment for accelerated oxygen gas evolution, whereas the un-confined system proceeds with a relatively slower kinetics. The outstanding OER activity and excellent stability, with an overpotential of 300 mV at 100 mA cm−2 and Tafel slope as low as 93 mV dec−1 results from the confinement effect. This study sheds light on the OER mechanism of confined catalysis and opens up a way to develop efficient and low-cost electrocatalysts.
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| 19. |
- Ibrahim, Kassa Belay, et al.
(författare)
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Facile Electron Transfer in Atomically Coupled Heterointerface for Accelerated Oxygen Evolution
- 2023
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Ingår i: Small. - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- An efficient and cost-effective approach for the development of advanced catalysts has been regarded as a sustainable way for green energy utilization. The general guideline to design active and efficient catalysts for oxygen evolution reaction (OER) is to achieve high intrinsic activity and the exposure of more density of the interfacial active sites. The heterointerface is one of the most attractive ways that plays a key role in electrochemical water oxidation. Herein, atomically cluster-based heterointerface catalysts with strong metal support interaction (SMSI) between WMn2O4 and TiO2 are designed. In this case, the WMn2O4 nanoflakes are uniformly decorated by TiO2 particles to create electronic effect on WMn2O4 nanoflakes as confirmed by X-ray absorption near edge fine structure. As a result, the engineered heterointerface requires an OER onset overpotential as low as 200 mV versus reversible hydrogen electrode, which is stable for up to 30 h of test. The outstanding performance and long-term durability are due to SMSI, the exposure of interfacial active sites, and accelerated reaction kinetics. To confirm the synergistic interaction between WMn2O4 and TiO2, and the modification of the electronic structure, high-resolution transmission electron microscopy (HR-TEM), X-ray photoemission spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) are used.
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| 20. |
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| 21. |
- Kumar, Pankaj, et al.
(författare)
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Recent Progress in Materials and Device Design for Semitransparent Photovoltaic Technologies
- 2023
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Ingår i: Advanced Energy Materials. - : John Wiley & Sons. - 1614-6832 .- 1614-6840. ; 13:39
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Forskningsöversikt (refereegranskat)abstract
- Semitransparent photovoltaic (STPV) solar cells offer an immense opportunity to expand the scope of photovoltaics to special applications such as windows, facades, skylights, and so on. These new opportunities have encouraged researchers to develop STPVs using traditional thin-film solar cell technologies (amorphous-Si, CdTe, and CIGS or emerging solar cells (organic, perovskites, and dye-sensitized). There are considerable improvements in both power conversion efficiency (PCE) and semitransparency of these STPV devices. This review studies the device structure of state-of-the-art STPV devices and thereby analyzes the different approaches toward maximizing the product of PCE and average visible transmittance. The origins of PCE losses during the opaque-to-semitransparent transition in the different STPV technologies are discussed. In addition, critical practical aspects relevant to all STPV devices, such as compatibility of the top transparent electrode with the device structure, buffer layer optimization, light management engineering, scale-up, and stability, are also reported. This overview is expected to facilitate researchers across different technologies to identify and overcome the challenges toward achieving higher light utilization efficiencies in STPVs.
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| 22. |
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| 23. |
- Kumar, Shusheel, et al.
(författare)
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Transforming NiCo2O4 nanorods into nanoparticles using citrus lemon juice enhancing electrochemical properties for asymmetric supercapacitor and water oxidation
- 2023
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 13:27, s. 18614-18626
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Tidskriftsartikel (refereegranskat)abstract
- Recently, the nanostructured nickel–cobalt bimetallic oxide (NiCo2O4) material with high electrochemical activity has received intensive attention. Beside this, the biomass assisted synthesis of NiCo2O4 is gaining popularity due to its advantageous features such as being low cost, simplicity, minimal use of toxic chemicals, and environment-friendly and ecofriendly nature. The electrochemical activity of spinel NiCo2O4 is associated with its mixed metal oxidation states. Therefore, much attention has been paid to the crystal quality, morphology and tunable surface chemistry of NiCo2O4 nanostructures. In this study, we have used citrus lemon juice consisting of a variety of chemical compounds having the properties of a stabilizing agent, capping agent and chelating agent. Moreover, the presence of several acidic chemical compounds in citrus lemon juice changed the pH of the growth solution and consequently we observed surface modified and structural changes that were found to be very effective for the development of energy conversion and energy storage systems. These naturally occurring compounds in citrus lemon juice played a dynamic role in transforming the nanorod morphology of NiCo2O4 into small and well-packed nanoparticles. Hence, the prepared NiCo2O4 nanostructures exhibited a new surface-oriented nanoparticle morphology, high concentration of defects on the surface (especially oxygen vacancies), sufficient ionic diffusion and reaction of electrolytic ions, enhanced electrical conductivity, and favorable reaction kinetics at the interface. The electrocatalytic properties of the NiCo2O4 nanostructures were studied in oxygen evolution reaction (OER) at a low overpotential of 250 mV for 10 mA cm−2, Tafel slope of 98 mV dec−1, and durability of 40 h. Moreover, an asymmetric supercapacitor was produced and the obtained results indicated a high specific capacitance of (Cs) of 1519.19 F g−1, and energy density of 33.08 W h kg−1 at 0.8 A g−1. The enhanced electrochemical performance could be attributed to the favorable structural changes, surface modification, and surface crystal facet exposure due to the use of citrus lemon juice. The proposed method of transformation of nanorod to nanoparticles could be used for the design of a new generation of efficient electrocatalyst materials for energy storage and conversion uses.
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| 24. |
- Li, Jiurong, et al.
(författare)
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High-loading of organosilane-grafted carbon dots in high-performance luminescent solar concentrators with ultrahigh transparency
- 2023
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Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 115
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Tidskriftsartikel (refereegranskat)abstract
- Carbon dots (CDs) generally suffer from aggregation-induced fluorescence quenching effect in solid-state, which significantly limits their application in photoelectric devices. Due to this effect, it is a great challenge to achieve high-transparency and high-performance luminescent solar concentrators (LSCs) based on CDs. Here, the synthesis of organosilane-grafted carbon dots (Si-CDs) is rationally designed by hydrothermal method using anhydrous citric acid, ethanolamine and KH-792 as the reaction precursors. The obtained Si-CDs can be uniformly dispersed in the polyvinyl alcohol (PVA) matrix through the dehydration condensation reaction and hydrogen bonding between the silicon hydroxyl group of Si-CDs and the hydroxyl group of PVA. Based on this property, Si-CDs/PVA thin-film LSCs (5 × 5 × 0.2 cm3) with ultrahigh CD loading (25 wt%) and high transparency can be fabricated, exhibiting excellent absorption in the UV spectral region and about 90 % transmission in the visible range. Furthermore, the power conversion efficiency (PCE) of the LSCs can reach 2.09 % under a standard solar light and shows excellent stability even over 12 weeks. This synthetic design is expected to be beneficial for future development of CD synthesis and paves the way for the development of CDs-based photoelectric devices.
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| 25. |
- Liccardo, Letizia, et al.
(författare)
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Surface Defect Engineering in Colored TiO2 Hollow Spheres Toward Efficient Photocatalysis
- 2023
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Ingår i: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 33:22
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured TiO2 is one of the best materials for photocatalysis, thanks to its high surface area and surface reactivity, but its large energy bandgap (3.2 eV) hinders the use of the entire solar spectrum. Here, it is proposed that defect-engineered nanostructured TiO2 photocatalysts are obtained by hydrogenation strategy to extend its light absorption up to the near-infrared region. It is demonstrated that hydrogenated or colored TiO2 hollow spheres (THS) composed of hierarchically assembled nanoparticles result in much broader exploitation of the solar spectrum (up to 1200 nm) and the engineered surface enhances the photogeneration of charges for photocatalytic processes. In turn, when applied for photodegradation of a targeted drug (Ciprofloxacin) this results in 82% degradation after 6 h under simulated sunlight. Valence band analysis by photoelectron spectroscopy revealed the presence of oxygen vacancies, whose surface density increases with the hydrogenation rate. Thus, a tight correlation between degree of hydrogenation and photocatalytic activity is directly established. Further insight comes from electron paramagnetic resonance, which evidences bulk Ti3+ centers only in hydrogenated THS. The results are anticipated to disclose a new path toward highly efficient photocatalytic titania in a series of applications targeting water remediation and solar fuel production.
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