Papers by Nina Christina Berner
arXiv (Cornell University), May 22, 2015
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Physica status solidi, Feb 15, 2012
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ECS Meeting Abstracts, 2015
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The reduction of dimensionality has revealed exciting properties in layered 2D materials such as ... more The reduction of dimensionality has revealed exciting properties in layered 2D materials such as graphene and transition metal dichalcogenides (TMDs). In order to use these materials in functional devices, processes for reliable large scale synthesis, functionalization and integration must be developed. Here we present the thermally assisted conversion of various TMD layers. The sulfides and selenides of Mo and W have been produced on silicon chips. These films have been characterized thoroughly and electrically addressed. Furthermore, we report on CVD growth of MoS2 and WS2 monolayers in a microreactor setup. Besides transistor applications, TMDs can be used for other electronic applications such as chemical sensors and photodiodes. Integrating novel 2D materials with silicon technology may lead to significant advances toward a wide range of novel devices.
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Chemical Physics Letters, Nov 1, 2014
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ACS Nano, Sep 30, 2016
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Chemistry: A European Journal, Sep 9, 2020
Covalently tethering photosensitizers to catalytically active 1T-MoS 2 surfaces holds great promi... more Covalently tethering photosensitizers to catalytically active 1T-MoS 2 surfaces holds great promise for the solar-driven hydrogen evolution reaction (HER). Herein we report the preparation of two new Ru II complex functionalized MoS 2 hybrids [Ru II (bpy) 2 (phen)]-MoS 2 and [Ru II (bpy) 2 (py)Cl]-MoS 2 . The influence of covalent functionalization of chemically exfoliated 1T-MoS 2 with coordinating ligands and Ru II complexes on the HER activity and photoelectrochemical performance of this dye-sensitized system was studied systematically. We find that the photoelectrochemical performance of this Ru II complex sensitized MoS 2 system is highly dependent on the surface extent of photosensitizers and the catalytic activity of functionalized MoS 2 . The latter was strongly affected by the number and the kind of functional groups. Our results underline the tunability of the photovoltage generation in this dye-sensitized MoS 2 system by manipulation of the surface functionalities, which provides a practical guidance for smart design of future dye-sensitized MoS 2 hydrogen production devices towards improved the photo-fuel conversion efficiency.
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Meeting abstracts, 2016
Alkaline water electrolysis produces H2 gas, which can be used as a fuel in H2/O2 fuel cells to g... more Alkaline water electrolysis produces H2 gas, which can be used as a fuel in H2/O2 fuel cells to generate power. The most energy intensive step in water electrolysis is the evolution of O2 due to the large anodic overpotential of the Oxygen Evolution Reaction (OER).1 Thus, understanding and optimizing electrocatalysts for OER remains one of the grand challenges for both physical electrochemistry and energy science. For the OER in alkaline media, the best performing electrocatalysts are thermally prepared RuO2 and IrO2, which exhibit the lowest OER overpotentials to date, but these oxides are expensive and somewhat unstable in alkaline media, rendering them impractical and uneconomical.1 First row Transition Metal Oxides (TMO), e.g. Mn, Ni, Co or Fe, show great promise as alternative materials for OER, as they exhibit low overpotentials and high stability at lower costs than those of RuO2 or IrO2. However, mechanistic studies of OER at TMO electrodes in alkaline media have been sparse and the nature of catalytic sites and the mechanism leading to O2 evolution are not well understood.2 In this work, pure and mixed Ni/Fe materials were electrochemically deposited on Ti supports to fabricate inexpensive electrocatalysts. Their potential as OER catalysts was elucidated in NaOH electrolyte with different amounts of Fe impurities; 1 ppb, 5 ppb and 102 ppb, as determined by Inductive Coupled Plasma (ICP) spectroscopy. The results indicate that the electrocatalytic activity of the materials depends on the ratio of Ni/Fe and the concentration of Fe impurities in the electrolyte. Most of the mixed catalysts show improved OER performances compared to the pure Ni and Fe oxide materials with respect to overpotential at 10 mA cm-2, Figure 1(a), Tafel slope values and Turnover Frequencies (TOF) numbers. Interestingly, the pure and mixed Ni/Fe materials in the NaOH electrolyte containing 5 ppb Fe impurities exhibited lower overpotentials at 10mA cm-2 compared to the same material in the NaOH containing 1 ppb and 100 ppb, Figure 1(a). This is thought to be due to the substitution of the Fe ions in the electrolyte for the Ni atoms in the material lattice, improving the OER performance.3 Pure and mixed manganese and ruthenium oxides were also examined in this work. The OER catalytic activity of pure manganese oxide compounds displaying overpotentials between 0.74 - 0.49 V at a current density of 10 mA cm-2. Furthermore, when combined with other compounds this overpotential value further decreases.4 However, mechanistic studies of the OER at thermally prepared DSA® type MnxOy electrodes in alkaline media have been sparse.2 Several of the mixed Mn/Ru electrode materials in this study were found to exhibit significantly improved OER activity and stability when compared with pure RuO2films, Figure 1(b), while lowering the cost of producing the catalyst.5 These Mn/Ru materials could therefore offer a competitive low-cost alternative to the already commercially available OER catalysts. The composition, morphology and structure of all the aforementioned materials are thoroughly characterised by X-Ray Photoelectron Spectroscopy (XPS), Raman spectroscopy and Scanning Electron Microscopy–Energy Dispersive X-Ray (SEM-EDX). Finally, the Ni/Fe and Mn/Ru oxides will be a compared under cost and OER performance, to help identify the most economic and practical OER catalyst in this work. Acknowledgements We would like to thank Science Foundation Ireland (SFI) under the Grant Number SFI/10/IN.1/I2969. References (1) Lyons, M. E. G.; Doyle, R. L.; Fernandez, D.; Godwin, I. J.; Browne, M. P.; Rovetta, A. Electrochem. Commun. 2014, 45, 56-59. (2) Fernández, J. L.; Gennero De Chialvo, M. R.; Chialvo, A. C. J. Appl. Electrochem. 2002, 32, 513-520. (3) Klaus, S.; Louie, M. W.; Trotochaud, L.; Bell, A. T. The Journal of Physical Chemistry C 2015, 119, 18303-18316. (4) Gao, M.-R.; Xu, Y.-F.; Jiang, J.; Zheng, Y.-R.; Yu, S.-H. J. Am. Chem. Soc. 2012, 134, 2930-2933. (5) Browne, M. P.; Nolan, H.; Duesberg, G. S.; Colavita, P. E.; Lyons, M. E. G. ACS Catalysis 2016. Figure 1
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Carbon, Dec 1, 2015
Abstract The effect of adding chromium (Cr) to the copper catalyst for chemical vapour deposition... more Abstract The effect of adding chromium (Cr) to the copper catalyst for chemical vapour deposition growth of graphene is investigated. We observe a suppression of the formation of multilayer islands of graphene in the Cr-rich regions. This is shown with optical microscopy, scanning electron microscopy and scanning Raman spectroscopy. In addition, carbon isotope labelling is employed to elucidate the mechanism by which the formation of multilayer islands is minimised. The use of mixed catalysts is an important step in the optimisation of catalytic growth of graphene.
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Chemistry: A European Journal, Dec 7, 2020
Covalently tethering photosensitizers to catalytically active 1T-MoS 2 surfaces holds great promi... more Covalently tethering photosensitizers to catalytically active 1T-MoS 2 surfaces holds great promise for the solar-driven hydrogen evolution reaction (HER). Herein we report the preparation of two new Ru II complex functionalized MoS 2 hybrids [Ru II (bpy) 2 (phen)]-MoS 2 and [Ru II (bpy) 2 (py)Cl]-MoS 2 . The influence of covalent functionalization of chemically exfoliated 1T-MoS 2 with coordinating ligands and Ru II complexes on the HER activity and photoelectrochemical performance of this dye-sensitized system was studied systematically. We find that the photoelectrochemical performance of this Ru II complex sensitized MoS 2 system is highly dependent on the surface extent of photosensitizers and the catalytic activity of functionalized MoS 2 . The latter was strongly affected by the number and the kind of functional groups. Our results underline the tunability of the photovoltage generation in this dye-sensitized MoS 2 system by manipulation of the surface functionalities, which provides a practical guidance for smart design of future dye-sensitized MoS 2 hydrogen production devices towards improved the photo-fuel conversion efficiency.
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Chemical Communications, 2015
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ACS Applied Materials & Interfaces, Nov 1, 2016
We report on 2H-2H&#3... more We report on 2H-2H'/1T phase conversion of MoS2 and MoSe2 polycrystalline films grown by thermally assisted conversion. The structural conversion of the transition metal dichalcogenides was successfully carried out by organolithium treatment on chip. As a result we obtained a new 2H-2H'/1T cophase system of the TMDs thin films which was verified by Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The conversion was successfully carried out on selected areas yielding a lateral heterostructure between the pristine 2H phase and the 2H'/1T cophase regions. Scanning electron microscopy and atomic force microscopy revealed changes in the surface morphology and work function of the cophase system in comparison to the pristine films, with a surprisingly sharp lateral interface region.
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Journal of materials chemistry. A, Materials for energy and sustainability, 2016
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Nanoscale, 2014
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2D materials, Apr 13, 2016
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Advanced Materials Interfaces, Aug 4, 2015
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Carbon, May 1, 2014
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Chemical Communications, 2015
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International Journal of Electrochemical Science, Aug 1, 2016
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Advanced Materials Interfaces, May 7, 2014
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Papers by Nina Christina Berner