Publications by authors named "Kalliopi Ladomenou"

Article Synopsis
  • The study introduces a new hybrid photocatalytic nanomaterial made from porphyrin-carbon dot conjugates that generates hydrogen using visible light.
  • The researchers created M-TCPP-NCDots hybrids through amide coupling of metallated tetra-carboxyphenyl porphyrins with nitrogen-doped carbon dots, enabling hydrogen production without needing expensive metallic co-catalysts.
  • Key findings highlight that the covalent attachment and zinc-metallation of the porphyrin component are crucial for improving the system's efficiency, presenting a novel method for artificial photosynthesis.
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As society progresses and industrializes, the issue of water pollution, caused by a wide array of organic and inorganic pollutants, poses significant risks to both human well-being and the environment. Given its distinctive characteristics, water pollution has become a paramount concern for society, necessitating immediate attention. Numerous studies have been conducted on wastewater treatment, primarily focusing on two key approaches: adsorption and photocatalytic degradation.

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We developed dye-sensitized photocatalytic systems (DSPs) by utilizing porphyrins as a photosensitizer (PS) or as a photosensitizer-catalyst (PS/CAT) upon their chemisorption onto platinum-doped titanium dioxide nanoparticles (Pt-TiO NPs). The DSPs coated with Pt-Tc3CP (PS/CAT entity) exhibited a record-high stability (25 500 TONs) and H evolution activity (707 mmol g h) compared to similar DSPs in the literature.

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Article Synopsis
  • Solar energy conversion through light-induced splitting of water into oxygen and hydrogen shows promise for addressing global energy demands.
  • An efficient photocatalytic hydrogen production system was developed using low-cost nickel-based complexes and N-doped carbon dots, demonstrating varying efficiencies in hydrogen evolution.
  • Notably, a hexanuclear nickel complex exhibited significantly higher catalytic efficiency than mononuclear complexes, suggesting the importance of multiple metal centers in enhancing light-induced hydrogen production.
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Charge injection and transport interlayers play a crucial role in many classes of optoelectronics, including organic and perovskite ones. Here, we demonstrate the beneficial role of carbon nanodots, both pristine and nitrogen-functionalized, as electron transport materials in organic light emitting diodes (OLEDs) and organic solar cells (OSCs). Pristine (referred to as C-dots) and nitrogen-functionalized (referred to as NC-dots) carbon dots are systematically studied regarding their properties by using cyclic voltammetry, Fourier-transform infrared (FTIR) and UV-Vis absorption spectroscopy in order to reveal their energetic alignment and possible interaction with the organic semiconductor's emissive layer.

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Article Synopsis
  • The demand for renewable energy sources is urgent due to the environmental issues caused by fossil fuel over-exploitation, with hydrogen (H) as a promising zero-emission alternative, especially when produced from water.
  • Recent research on photocatalytic systems focuses on porphyrin and phthalocyanine derivatives which serve dual roles as both chromophores and catalysts for hydrogen production and CO reduction.
  • Developing effective heterogeneous photocatalytic systems involves various innovative methods, such as self-assembled nanostructures and dye-sensitized photoelectrochemical cells, although significant challenges remain before these systems can be applied on a large scale.
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Hydrogen is regarded as a promising molecular fuel in order to produce clean energy, thus it is of great importance to produce and store H in order to replace fossil fuels and to resolve the global energy and environmental problems. One strategy to produce hydrogen is the photocatalytic splitting of water. In this study different supramolecular architectures of a Zn(II) porphyrin, showing "flower", octahedral and "manta ray" shaped structures, were obtained using the "good-bad" solvent self-assembly protocol.

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In this study, a highly efficient photocatalytic H production system is developed by employing porphyrins as photocatalysts. Palladium and platinum tetracarboxyporphyrins (PdTCP and PtTCP) are adsorbed or coadsorbed onto TiO nanoparticles (NPs), which act as the electron transport medium and as a scaffold that promotes the self-organization of the porphyrinoids. The self-organization of PdTCP and PtTCP, forming H- and J-aggregates, respectively, is the key element for H evolution, as in the absence of TiO NPs no catalytic activity is detected.

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We report on the first systematic study of cobaloxime-based hydrogen photoproduction in mixed pH 7 aqueous/acetonitrile solutions and demonstrate that H2 evolution can be tuned through electronic modifications of the axial cobalt ligand or through introduction of TiO2 nanoparticles. The photocatalytic systems consist of various cobaloxime catalysts [Co(dmgH)2(L)Cl] (L = nitrogen-based axial ligands) and a water soluble porphyrin photosensitizer. They were assayed in the presence of triethanolamine as a sacrificial electron donor.

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Lately solar to power energy conversion devices have attracted a lot of attention and there is an effort to synthesize novel light-harvesting organic materials. Inspired by nature and due to their remarkable role in photosynthesis, porphyrins have been extensively used for DSSC and BHJ applications. This review provides a summary of the developments and approaches that were used in our group in order to improve the power conversion efficiency of DSSCs and BHJs based on porphyrin hybrid derivatives.

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In recent years, there has been a growing interest in the design and synthesis of chromophores, which absorb in a wide region of the visible spectrum, as these constitute promising candidates for use as sensitizers in various solar energy conversion schemes. In this work, a palladium-catalyzed coupling reaction was employed in the synthesis of molecular triads in which two porphyrin or boron dipyrrin (BDP) chromophores are linked to the meso positions of a central Zn porphyrin (PZn) ring via an amino group. In the resulting conjugates, which strongly absorb over most of the visible region, the electronic properties of the constituent chromophores are largely retained while detailed emission experiments reveal the energy transfer pathways that occur in each triad.

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Urea-functionalized porphyrins with amino acid substituents bind sugar derivatives strongly in non-polar solution.

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