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Author: Artero, Vincent × Author: Dietzek, Benjamin × End date: 2019 × Start date: 2010 × DDC: 540 × Version: publishedVersion ×

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    Structure of Ni(OH)2 intermediates determines the efficiency of NiO-based photocathodes – a case study using novel mesoporous NiO nanostars
    (Cambridge : RSC, 2019) Wahyuono, Ruri Agung; Dellith, Andrea; Schmidt, Christa; Dellith, Jan; Ignaszak, Anna; Seyring, Martin; Rettenmayr, Markus; Fize, Jennifer; Artero, Vincent; Chavarot-Kerlidou, Murielle; Dietzek, Benjamin
    We report the wet chemical synthesis of mesoporous NiO nanostars (NS) as photocathode material for dye-sensitized solar cells (DSSCs). The growth mechanism of NiO NS as a new morphology of NiO is assessed by TEM and spectroscopic investigations. The NiO NS are obtained upon annealing of preformed β-Ni(OH)2 into pristine NiO with low defect concentrations and favorable electronic configuration for dye sensitization. The NiO NS consist of fibers self-assembled from nanoparticles yielding a specific surface area of 44.9 m2 g-1. They possess a band gap of 3.83 eV and can be sensitized by molecular photosensitizers bearing a range of anchoring groups, e.g. carboxylic acid, phosphonic acid, and pyridine. The performance of NiO NS-based photocathodes in photoelectrochemical application is compared to that of other NiO morphologies, i.e. nanoparticles and nanoflakes, under identical conditions. Sensitization of NiO NS with the benchmark organic dye P1 leads to p-DSSCs with a high photocurrent up to 3.91 mA cm-2 whilst the photoelectrochemical activity of the NiO NS photocathode in aqueous medium in the presence of an irreversible electron acceptor is reflected by generation of a photocurrent up to 23 μA cm-2 © 2019 The Royal Society of Chemistry.
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    A comprehensive comparison of dye-sensitized NiO photocathodes for solar energy conversion
    (Cambridge : RSC Publ., 2015) Wood, Christopher J.; Summers, Gareth H.; Clark, Charlotte A.; Kaeffer, Nicolas; Braeutigam, Maximilian; Carbone, Lea Roberta; D'Amario, Luca; Fan, Ke; Farré, Yoann; Narbey, Stéphanie; Oswald, Frédéric; Stevens, Lee A.; Parmenter, Christopher D.J.; Fay, Michael W.; La Torre, Alessandro; Snape, Colin E.; Dietzek, Benjamin; Dini, Danilo; Hammarström, Leif; Pellegrin, Yann; Odobel, Fabrice; Sun, Licheng; Artero, Vincent; Gibson, Elizabeth A.
    We investigated a range of different mesoporous NiO electrodes prepared by different research groups and private firms in Europe to determine the parameters which influence good quality photoelectrochemical devices. This benchmarking study aims to solve some of the discrepancies in the literature regarding the performance of p-DSCs due to differences in the quality of the device fabrication. The information obtained will lay the foundation for future photocatalytic systems based on sensitized NiO so that new dyes and catalysts can be tested with a standardized material. The textural and electrochemical properties of the semiconducting material are key to the performance of photocathodes. We found that both commercial and non-commercial NiO gave promising solar cell and water-splitting devices. The NiO samples which had the two highest solar cell efficiency (0.145% and 0.089%) also gave the best overall theoretical H2 conversion.
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    An artificial photosynthetic system for photoaccumulation of two electrons on a fused dipyridophenazine (dppz)-pyridoquinolinone ligand
    (Cambridge : RSC Publishing, 2018) Lefebvre, Jean-François; Schindler, Julian; Traber, Philipp; Zhang, Ying; Kupfer, Stephan; Gräfe, Stefanie; Baussanne, Isabelle; Demeunynck, Martine; Mouesca, Jean-Marie; Gambarelli, Serge; Artero, Vincent; Dietzek, Benjamin; Chavarot-Kerlidou, Murielle
    Increasing the efficiency of molecular artificial photosynthetic systems is mandatory for the construction of functional devices for solar fuel production. Decoupling the light-induced charge separation steps from the catalytic process is a promising strategy, which can be achieved thanks to the introduction of suitable electron relay units performing charge accumulation. We report here on a novel ruthenium tris-diimine complex able to temporarily store two electrons on a fused dipyridophenazine-pyridoquinolinone π-extended ligand upon visible-light irradiation in the presence of a sacrificial electron donor. Full characterization of this compound and of its singly and doubly reduced derivatives thanks to resonance Raman, EPR and (TD)DFT studies allowed us to localize the two electron-storage sites and to relate charge photoaccumulation with proton-coupled electron transfer processes.