Yazar "Kargul, Joanna" seçeneğine göre listele

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    Plasmonic enhancement of photocurrent generation in a photosystem I-based hybrid electrode
    (Royal Soc Chemistry, 2020) Szalkowski, Marcin; Harputlu, Ersan; Kiliszek, Malgorzata; Unlu, C. Gokhan; Mackowski, Sebastian; Ocakoglu, Kasim; Kargul, Joanna
    We experimentally demonstrate that oriented assembly of red algal photosystem I (PSI) reaction centers on a plasmonically active Silver Island Film (SIF) leads to strong enhancement of both the fluorescence intensity and photocurrent generated upon illumination. PSI complexes were specifically attached to a monolayer of graphene deposited on the SIF layer. The results of comprehensive fluorescence microscopy point to the critical role of the SIF layer in enhancing the optical response of PSI, as we observe increased emission intensity. Hence, importantly, the strong increase of photocurrent generation demonstrated for the biohybrid electrodes can be directly associated with the plasmonic enhancement of the optical and electrochemical functionalities of PSI. The results also indicate that the graphene layer is not diminishing the influence of the plasmonic excitations in SIF on the absorption and emission of PSI.
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    Öğe
    Role of Metal Centers in Tuning the Electronic Properties of Graphene-Based Conductive Interfaces
    (Amer Chemical Soc, 2019) Osella, Silvio; Kiliszek, Malgorzata; Harputlu, Ersan; Unlu, Cumhur G.; Ocakoglu, Kasim; Trzaskowski, Bartosz; Kargul, Joanna
    A major bottleneck in the fabrication of efficient bio-organic nanoelectronic devices resides in the strong charge recombination that is present at the different interfaces forming the complex system. An efficient way to overcome this bottleneck is to add a self-assembled monolayer (SAM) of molecules between the biological material and electrode that promotes an efficient direct electron transfer while minimizing wasteful processes of charge recombination. In this work, the presence of a pyrene-nitrilotriacetic acid layer carrying different metal centers as the SAM is physisorbed on graphene is fully described by means of electrochemical analysis, field-emission scanning electron microscopy, photoelectrochemical characterization, and theoretical calculations. Our multidisciplinary study reveals that the metal center holds the key role in the efficient electron transfer at the interface. While Ni2+ is responsible for the electron transfer from the SAM to graphene, Co2+ and Cu2+ force an opposite transfer from graphene to SAM. Moreover, since Cu2+ inhibits the electron transfer due to a strong charge recombination, Co2+ seems to be the transition metal of choice for the efficient electron transfer.