Anastasios Stergiou | National Hellenic Research Foundation (original) (raw)
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Papers by Anastasios Stergiou
Metal nanoclusters (MNCs) based on silver and gold, abbreviated as AgNCs and AuNCs, respectively,... more Metal nanoclusters (MNCs) based on silver and gold, abbreviated as AgNCs and AuNCs, respectively, were synthesized and combined with functionalized graphene, abbreviated as f-G, forming novel MNC/f-G ensembles. The preparation of MNCs/f-G was achieved by employing attractive electrostatic interactions developed between negatively charged MNCs, attributed to the presence of carboxylates due to α-lipoic acid employed as a stabilizer, and positively charged f-G, attributed to the presence of ammonium units as addends. The realization of MNC/f-G ensembles was established via titration assays as evidenced by electronic absorption and photoluminescence spectroscopy as well as scanning transmission electron microscopy (STEM) and energy-dispersive X-ray (EDX) spectroscopy analyses. Photoinduced charge-transfer phenomena were inferred within MNCs/f-G, attributed to the suppression of MNC photoluminescence by the presence of f-G. Next, the MNC/f-G ensembles were successfully employed as profi...
Molybdenum disulfide nanosheets covalently modified with porphyrin were prepared and fully charac... more Molybdenum disulfide nanosheets covalently modified with porphyrin were prepared and fully characterized. Neither the porphyrin absorption nor its fluorescence was notably affected by covalent linkage to MoS2. The use of transient absorption spectroscopy showed that a complex ping‐pong energy‐transfer mechanism, namely from the porphyrin to MoS2 and back to the porphyrin, operated. This study reveals the potential of transition‐metal dichalcogenides in photosensitization processes.
Molybdenum disulfide (MoS2 ) nanosheets have attracted great scientific interest for their remark... more Molybdenum disulfide (MoS2 ) nanosheets have attracted great scientific interest for their remarkable electronic and optical properties. During the last few years significant progress on exfoliation methods of such nanosheets allowed the development of surface functionalization in covalent or noncovalent fashion. Markedly, the chemical modification allows tailoring and tuning the optical and electronic characteristics of MoS2 , opening new avenues for the potentiality of MoS2 -based hybrids in diverse technological fields. Physisorption of organic molecules onto MoS2 through the development of numerous van der Waals interactions is the most widely approach employed for the surface noncovalent immobilization of organic species onto MoS2 nanosheets. Conversely, developed strategies for the edge and in-plane covalent functionalization of MoS2 mainly concern chemistry at S vacancies, direct C-S bond formation, and coordination of S edges at metal centers. Herein, we focus into the most ...
Resumen del trabajo presentado al ChemOnTubes, International meeting on the chemistry of graphene... more Resumen del trabajo presentado al ChemOnTubes, International meeting on the chemistry of graphene and carbon nanotubes, celebrado en Biarritz (Francia) del 22 al 26 de abril de 2018.
Nanoscale
Molecular entities with robust spin-1/2 are natural two-level quantum systems for realizing qubit... more Molecular entities with robust spin-1/2 are natural two-level quantum systems for realizing qubits and are key ingredients of emerging quantum technologies such as quantum computing. Here we show that robust...
Chemistry – A European Journal
Metal-free Functionalized Carbons in Catalysis
Catalysis, as a general topic, concerns a wide range of chemical processes, which may be in eithe... more Catalysis, as a general topic, concerns a wide range of chemical processes, which may be in either homogeneous or heterogeneous modes of reaction. A major goal in related research involves the substitution of rare and expensive metal nanoparticle catalysts with alternative nanostructured materials, based on abundant elements. To this end, a lot of effort has been devoted to the development of catalytic systems based on various carbon allotropic forms. The synthesis of multifunctional nanocarbon-based catalysts is an emerging field of nanotechnology, due to the unique properties of these nanostructured materials. Specifically, their large specific surface area, high conductivity, and appreciable (electro)catalytic properties make them ideal candidates as functional components in various schemes of chemical energy transformation. In this chapter, we will describe the synthetic methodologies and catalytic applications of representative metal-free carbon-based assemblies. The allotropic forms discussed are graphene, fullerenes, carbon nanotubes, nanodiamonds, carbon nanohorns and carbon quantum dots.
Applied Catalysis B: Environmental
Nanoscale
The coating of perovskites with D35 improves the performance of PSCs. D35 plays a versatile funct... more The coating of perovskites with D35 improves the performance of PSCs. D35 plays a versatile functional role.
RSC Advances
Azafullerene C59N was modified by a pentafluoroquinoline (FQ) derivative, the amphoteric quinolin... more Azafullerene C59N was modified by a pentafluoroquinoline (FQ) derivative, the amphoteric quinoline domain was utilized for the molecular recognition of C59N-FQ by a porphyrin-dimer (H2P)2 and host–guest interactions in (H2P)2/C59N-FQ were assessed.
Progress in Materials Science
ACS Applied Energy Materials
Angewandte Chemie
Molybdenum disulfide nanosheets covalently modified with porphyrin were prepared and fully charac... more Molybdenum disulfide nanosheets covalently modified with porphyrin were prepared and fully characterized. Neither the porphyrin absorption nor its fluorescence was notably affected by covalent linkage to MoS 2 . The use of transient absorption spectroscopy showed that a complex pingpong energy-transfer mechanism, namely from the porphyrin to MoS 2 and back to the porphyrin, operated. This study reveals the potential of transition-metal dichalcogenides in photosensitization processes.
![Research paper thumbnail of Long-lived azafullerenyl radical stabilized by supramolecular shielding with a [10]cycloparaphenylene](https://attachments.academia-assets.com/66386962/thumbnails/1.jpg)
](Angewandte Chemie International Edition
Am ajor handicap towards the exploitation of radicals is their inherent instability.I nt he param... more Am ajor handicap towards the exploitation of radicals is their inherent instability.I nt he paramagnetic azafullerenyl radical C 59 NC,t he unpaired electron is strongly localized next to the nitrogen atom, which induces dimerization to diamagnetic bis(azafullerene), (C 59 N) 2 .C onventional stabilization by introducing steric hindrance around the radical is inapplicable here because of the concave fullerene geometry. Instead, we developed an innovative radical shielding approach based on supramolecular complexation, exploiting the protection offered by a[ 10]cycloparaphenylene ([10]CPP) nanobelt encircling the C 59 NC radical. Photoinduced radical generation is increased by af actor of 300. The EPR signal showing characteristic 14 Nh yperfine splitting of C 59 NC& [10]CPP was traced even after several weeks,w hichc orresponds to alifetime increase of > 10 8 .The proposed approach can be generalized by tuning the diameter of the employed nanobelts,opening new avenues for the design and exploitation of radical fullerenes.
Nanoscale
The high (photo)electrocatalytic activity and stability towards the oxygen reduction reaction of ... more The high (photo)electrocatalytic activity and stability towards the oxygen reduction reaction of a star-shaped oligothiophene/S-doped graphene ensemble is presented.
Advanced Functional Materials
Conjugated polymers (CPs) constitute the base of organic thin film optoelectronic devices, such a... more Conjugated polymers (CPs) constitute the base of organic thin film optoelectronic devices, such as organic photovoltaic solar cells (OSCs) and organic light emitting devices (OLEDs). Deposited onto large areas of any shape they critically contribute to the development of selfpowered, smart and ubiquitous communication platforms. Operational performance and fabrication from "green" solutions compatible with large-area coating or printing technologies, are key requirements for their commercial implementation. Applying selfassembly strategies, CPs can be prepared in the form of water dispersible nanoparticles [1] being of actual interest for achieving improved device performance . In this work we provide novel pathways for the design of improved organic thin film optoelectronic devices by marrying nanoparticles of CPs (CPNPs) with 2D sheets of graphene oxide (GO) . Using poly(3-hexylthiophene) (P3HT) as benchmark CP, we demonstrate the game-changing role of GO in tuning the excitonic aggregate behavior of P3HTNPs and the efficient formation P3HTNPs-GO charge-transfer complexes Thin films thereof reveal improved separation of photo-generated charge carriers. Their performance only depends on the optoelectronic properties established in the liquid phase. The possibility to overcome external performance limitations and to employ "green" processing technologies offers exciting possibilities for further progress in the field of organic thin film optoelectronic devices.
Chemistry – A European Journal
Chemistry - A European Journal
Metal nanoclusters (MNCs) based on silver and gold, abbreviated as AgNCs and AuNCs, respectively,... more Metal nanoclusters (MNCs) based on silver and gold, abbreviated as AgNCs and AuNCs, respectively, were synthesized and combined with functionalized graphene, abbreviated as f-G, forming novel MNC/f-G ensembles. The preparation of MNCs/f-G was achieved by employing attractive electrostatic interactions developed between negatively charged MNCs, attributed to the presence of carboxylates due to α-lipoic acid employed as a stabilizer, and positively charged f-G, attributed to the presence of ammonium units as addends. The realization of MNC/f-G ensembles was established via titration assays as evidenced by electronic absorption and photoluminescence spectroscopy as well as scanning transmission electron microscopy (STEM) and energy-dispersive X-ray (EDX) spectroscopy analyses. Photoinduced charge-transfer phenomena were inferred within MNCs/f-G, attributed to the suppression of MNC photoluminescence by the presence of f-G. Next, the MNC/f-G ensembles were successfully employed as profi...
Molybdenum disulfide nanosheets covalently modified with porphyrin were prepared and fully charac... more Molybdenum disulfide nanosheets covalently modified with porphyrin were prepared and fully characterized. Neither the porphyrin absorption nor its fluorescence was notably affected by covalent linkage to MoS2. The use of transient absorption spectroscopy showed that a complex ping‐pong energy‐transfer mechanism, namely from the porphyrin to MoS2 and back to the porphyrin, operated. This study reveals the potential of transition‐metal dichalcogenides in photosensitization processes.
Molybdenum disulfide (MoS2 ) nanosheets have attracted great scientific interest for their remark... more Molybdenum disulfide (MoS2 ) nanosheets have attracted great scientific interest for their remarkable electronic and optical properties. During the last few years significant progress on exfoliation methods of such nanosheets allowed the development of surface functionalization in covalent or noncovalent fashion. Markedly, the chemical modification allows tailoring and tuning the optical and electronic characteristics of MoS2 , opening new avenues for the potentiality of MoS2 -based hybrids in diverse technological fields. Physisorption of organic molecules onto MoS2 through the development of numerous van der Waals interactions is the most widely approach employed for the surface noncovalent immobilization of organic species onto MoS2 nanosheets. Conversely, developed strategies for the edge and in-plane covalent functionalization of MoS2 mainly concern chemistry at S vacancies, direct C-S bond formation, and coordination of S edges at metal centers. Herein, we focus into the most ...
Resumen del trabajo presentado al ChemOnTubes, International meeting on the chemistry of graphene... more Resumen del trabajo presentado al ChemOnTubes, International meeting on the chemistry of graphene and carbon nanotubes, celebrado en Biarritz (Francia) del 22 al 26 de abril de 2018.
Nanoscale
Molecular entities with robust spin-1/2 are natural two-level quantum systems for realizing qubit... more Molecular entities with robust spin-1/2 are natural two-level quantum systems for realizing qubits and are key ingredients of emerging quantum technologies such as quantum computing. Here we show that robust...
Chemistry – A European Journal
Metal-free Functionalized Carbons in Catalysis
Catalysis, as a general topic, concerns a wide range of chemical processes, which may be in eithe... more Catalysis, as a general topic, concerns a wide range of chemical processes, which may be in either homogeneous or heterogeneous modes of reaction. A major goal in related research involves the substitution of rare and expensive metal nanoparticle catalysts with alternative nanostructured materials, based on abundant elements. To this end, a lot of effort has been devoted to the development of catalytic systems based on various carbon allotropic forms. The synthesis of multifunctional nanocarbon-based catalysts is an emerging field of nanotechnology, due to the unique properties of these nanostructured materials. Specifically, their large specific surface area, high conductivity, and appreciable (electro)catalytic properties make them ideal candidates as functional components in various schemes of chemical energy transformation. In this chapter, we will describe the synthetic methodologies and catalytic applications of representative metal-free carbon-based assemblies. The allotropic forms discussed are graphene, fullerenes, carbon nanotubes, nanodiamonds, carbon nanohorns and carbon quantum dots.
Applied Catalysis B: Environmental
Nanoscale
The coating of perovskites with D35 improves the performance of PSCs. D35 plays a versatile funct... more The coating of perovskites with D35 improves the performance of PSCs. D35 plays a versatile functional role.
RSC Advances
Azafullerene C59N was modified by a pentafluoroquinoline (FQ) derivative, the amphoteric quinolin... more Azafullerene C59N was modified by a pentafluoroquinoline (FQ) derivative, the amphoteric quinoline domain was utilized for the molecular recognition of C59N-FQ by a porphyrin-dimer (H2P)2 and host–guest interactions in (H2P)2/C59N-FQ were assessed.
Progress in Materials Science
ACS Applied Energy Materials
Angewandte Chemie
Molybdenum disulfide nanosheets covalently modified with porphyrin were prepared and fully charac... more Molybdenum disulfide nanosheets covalently modified with porphyrin were prepared and fully characterized. Neither the porphyrin absorption nor its fluorescence was notably affected by covalent linkage to MoS 2 . The use of transient absorption spectroscopy showed that a complex pingpong energy-transfer mechanism, namely from the porphyrin to MoS 2 and back to the porphyrin, operated. This study reveals the potential of transition-metal dichalcogenides in photosensitization processes.
Angewandte Chemie International Edition
Am ajor handicap towards the exploitation of radicals is their inherent instability.I nt he param... more Am ajor handicap towards the exploitation of radicals is their inherent instability.I nt he paramagnetic azafullerenyl radical C 59 NC,t he unpaired electron is strongly localized next to the nitrogen atom, which induces dimerization to diamagnetic bis(azafullerene), (C 59 N) 2 .C onventional stabilization by introducing steric hindrance around the radical is inapplicable here because of the concave fullerene geometry. Instead, we developed an innovative radical shielding approach based on supramolecular complexation, exploiting the protection offered by a[ 10]cycloparaphenylene ([10]CPP) nanobelt encircling the C 59 NC radical. Photoinduced radical generation is increased by af actor of 300. The EPR signal showing characteristic 14 Nh yperfine splitting of C 59 NC& [10]CPP was traced even after several weeks,w hichc orresponds to alifetime increase of > 10 8 .The proposed approach can be generalized by tuning the diameter of the employed nanobelts,opening new avenues for the design and exploitation of radical fullerenes.
Nanoscale
The high (photo)electrocatalytic activity and stability towards the oxygen reduction reaction of ... more The high (photo)electrocatalytic activity and stability towards the oxygen reduction reaction of a star-shaped oligothiophene/S-doped graphene ensemble is presented.
Advanced Functional Materials
Conjugated polymers (CPs) constitute the base of organic thin film optoelectronic devices, such a... more Conjugated polymers (CPs) constitute the base of organic thin film optoelectronic devices, such as organic photovoltaic solar cells (OSCs) and organic light emitting devices (OLEDs). Deposited onto large areas of any shape they critically contribute to the development of selfpowered, smart and ubiquitous communication platforms. Operational performance and fabrication from "green" solutions compatible with large-area coating or printing technologies, are key requirements for their commercial implementation. Applying selfassembly strategies, CPs can be prepared in the form of water dispersible nanoparticles [1] being of actual interest for achieving improved device performance . In this work we provide novel pathways for the design of improved organic thin film optoelectronic devices by marrying nanoparticles of CPs (CPNPs) with 2D sheets of graphene oxide (GO) . Using poly(3-hexylthiophene) (P3HT) as benchmark CP, we demonstrate the game-changing role of GO in tuning the excitonic aggregate behavior of P3HTNPs and the efficient formation P3HTNPs-GO charge-transfer complexes Thin films thereof reveal improved separation of photo-generated charge carriers. Their performance only depends on the optoelectronic properties established in the liquid phase. The possibility to overcome external performance limitations and to employ "green" processing technologies offers exciting possibilities for further progress in the field of organic thin film optoelectronic devices.
Chemistry – A European Journal
Chemistry - A European Journal