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“Experimental and computational investigation of graphene/SAMs/n-Si Schottky diodes”. Aydin H, Bacaksiz C, Yagmurcukardes N, Karakaya C, Mermer O, Can M, Senger RT, Sahin H, Selamet Y, Applied Surface Science 428, 1010 (2018). http://doi.org/10.1016/J.APSUSC.2017.09.204
Abstract: We have investigated the effect of two different self-assembled monolayers (SAMs) on electrical characteristics of bilayer graphene (BLG)/n-Si Schottky diodes. Novel 4“bis(diphenylamino)-1, 1':3”-terpheny1-5' carboxylic acids (TPA) and 4,4-di-9H-carbazol-9-y1-1,1':3'1'-terpheny1-5' carboxylic acid (CAR) aromatic SAMs have been used to modify n-Si surfaces. Cyclic voltammetry (CV) and Kelvin probe force microscopy (KPFM) results have been evaluated to verify the modification of n-Si surface. The current-voltage (I-V) characteristics of bare and SAMs modified devices show rectification behaviour verifying a Schottky junction at the interface. The ideality factors (n) from ln(I)-V dependences were determined as 2.13,1.96 and 2.07 for BLG/n-Si, BLG/TPA/n-Si and BLG/CAR/n-Si Schottky diodes, respectively. In addition, Schottky barrier height (SBH) and series resistance (Rs) of SAMs modified diodes were decreased compared to bare diode due to the formation of a compatible interface between graphene and Si as well as n-n interaction between aromatic SAMs and graphene. The CAR-based device exhibits better diode characteristic compared to the TPA-based device. Computational simulations show that the BLG/CAR system exhibits smaller energy-level-differences than the BLG/TPA, which supports the experimental findings of a lower Schottky barrier and series resistance in BLG/CAR diode. (C) 2017 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.387
Times cited: 2
DOI: 10.1016/J.APSUSC.2017.09.204
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“A comparative DFT study on CO oxidation reaction over Si-doped BC2N nanosheet and nanotube”. Nematollahi P, Neyts EC, Applied surface science 439, 934 (2018). http://doi.org/10.1016/J.APSUSC.2017.12.254
Abstract: In this study, we performed density functional theory (DFT) calculations to investigate different reaction mechanisms of CO oxidation catalyzed by the Si atom embedded defective BC2N nanostructures as well as the analysis of the structural and electronic properties. The structures of all the complexes are optimized and characterized by frequency calculations at the M062X/6-31G* computational level. Also, The electronic structures and thermodynamic parameters of adsorbed CO and O-2 molecules over Si-doped BC2N nanostructures are examined in detail. Moreover, to investigate the curvature effect on the CO oxidation reaction, all the adsorption and CO oxidation reactions on a finite-sized armchair (6,6) Si-BC2NNT are also studied. Our results indicate that there can be two possible pathways for the CO oxidation with O-2 molecule: O-2(g) + CO(g) -> O-2(ads) + CO(ads) -> CO2(g) + O-(ads) and O-(ads) + CO(g) -> CO2(g). The first reaction proceeds via the Langmuir-Hinshelwood (LH) mechanism while the second goes through the Eley-Rideal (ER) mechanism. On the other hand, by increasing the tube diameter, the energy barrier increases due to the strong adsorption energy of the O-2 molecule which is related to its dissociation over the tube surface. Our calculations indicate that the two step energy barrier of the oxidation reaction over Si-BC2NNS is less than that over the Si-BC2NNT. Hence, Si-BC2NNS may serve as an efficient and highly activated substrate to CO oxidation rather than (4,4) Si-BC2NNT. (C) 2018 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.387
Times cited: 8
DOI: 10.1016/J.APSUSC.2017.12.254
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“Tailoring the functional properties of polyurethane foam with dispersions of carbon nanofiber for power generator applications”. Sathiyamoorthy S, Girijakumari G, Kannan P, Venugopal K, Thiruvottriyur Shanmugam S, Veluswamy P, De Wael K, Ikeda H, Applied surface science 449, 507 (2018). http://doi.org/10.1016/J.APSUSC.2018.01.088
Abstract: To produce effective thermoelectric nanocomposites, carbon nanofibers (CNF) incorporated polyurethane (PU) foams with nanocomposites are prepared via in-situ polymerization method to create a synergy that would produce a high thermopower. The formation mechanism of foams, the reaction kinetics, and the physical properties such as density and water absorption studied before and after CNF incorporation. The microscopy images showed a uniform dispersion of CNF in the PU matrix of the prepared foams. Spectroscopic studies such as X-ray photoelectron and laser Raman spectroscopy suggested the existence of a tight intermolecular binding interaction between the carbon nanofibers and the PU matrix in the prepared composite foams. It found that the thermopower is directly dependent on the concentration of carbon nanofiber since, with rising concentration of 1%3%, the coefficient values increased from 1.2 μV/K to 11.9 μV/K respectively, a value higher than that of earlier report. This unique nanocomposite offers a new opportunity to recycle waste heat in portable/wearable electronics and other applications, which will broaden the development of low weight and mechanical flexibility.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 3.387
Times cited: 4
DOI: 10.1016/J.APSUSC.2018.01.088
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“Direct methane conversion to methanol on M and MN4 embedded graphene (M = Ni and Si): a comparative DFT study”. Nematollahi P, Neyts EC, Applied surface science 496, 143618 (2019). http://doi.org/10.1016/J.APSUSC.2019.143618
Abstract: The ever increasing global production and dispersion of methane requires novel chemistry to transform it into easily condensable energy carriers that can be integrated into the chemical infrastructure. In this context, single atom catalysts have attracted considerable interest due to their outstanding catalytic activity. We here use density functional theory (DFT) computations to compare the reaction and activation energies of M and MN4 embedded graphene (M = Ni and Si) on the methane-to-methanol conversion near room temperature. Thermodynamically, conversion of methane to methanol is energetically favorable at ambient conditions. Both singlet and triplet spin state of the studied systems are considered in all of the calculations. The DFT results show that the barriers are significantly lower when the complexes are in the triplet state than in the singlet state. In particular, Si-G with the preferred spin multiplicity of triplet seems to be viable catalysts for methane oxidation thanks to the corresponding lower energy barriers and higher stability of the obtained configurations. Our results provide insights into the nature of methane conversion and may serve as guidance for fabricating cost-effective graphene-based single atom catalysts.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.387
Times cited: 2
DOI: 10.1016/J.APSUSC.2019.143618
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