Publications by Year: 2015

Labropoulos A, Veziri C, Kapsi M, Pilatos G, Likodimos V, Tsapatsis M, Kanellopoulos NK, Romanos GE, Karanikolos GN. Carbon Nanotube Selective Membranes with Subnanometer, Vertically Aligned Pores, and Enhanced Gas Transport Properties. Chemistry of Materials [Internet]. 2015;27:8198-8210. WebsiteAbstract
Membranes consisting of ultrathin, oriented, single-wall carbon nanotube (SWCNT) micropores with a diameter of ∼4 Å were developed. c-Oriented AFI-type aluminophosphate (AlPO) films (AlPO4-5 and CoAPO-5), consisting of parallel channels 7.3 Å in diameter, were first fabricated by seeded growth on macroporous alumina supports, and used as templates for synthesis of CNTs inside the zeolitic channels by thermal treatment, utilizing the structure directing agent (amine) occluded in the channels as carbon source. Incorporation of CNTs inside the AFI channels altered the transport mechanism of all permeating gases tested, and imposed a substantial increase in their permeation rates, in comparison to the AlPO4-5 membrane, despite the pore size reduction due to nanotube growth. The enhancement of the permeation rates is attributed to repulsive potentials between gas molecules and occluded nanotubes, which limit adsorption strength and enhance diffusivity, coupled to the smooth SWCNT surface that enables fast diffusion through the nanotube interior. Separation ability, evaluated with respect to H2 and CO2 gases, was enhanced by using polysterene as defect-blocking medium on both AlPO and CNT/AlPO membranes and was preserved after CNT growth. © 2015 American Chemical Society.
Perganti D, Kontos AG, Stergiopoulos T, Likodimos V, Farnell J, Milliken D, Desilvestro H, Falaras P. Thermal Stressing of Dye Sensitized Solar Cells Employing Robust Redox Electrolytes. Electrochimica Acta [Internet]. 2015;179:241-249. WebsiteAbstract
Robust Dye Sensitized Solar Cells have been prepared employing liquid electrolytes using ethyl isopropyl sulfone (EiPS) high boiling point solvent. The cells were tested for their durability under harsh thermal stressing conditions of 85 °C and prolonged ageing time, 3000 h in the dark. The use of EiPS outperforms stability-wise the typical methoxypropionitrile MPN solvent, improving the cell stability from 38 to 75%. For both solvents, the physicochemical analysis infers the thermal degradation of the cell with the main changes occurring in the first 300 h of ageing. This was attributed to partial triiodide loss which reduces short circuit photocurrent and leads to formation of luminescent species in the electrolyte that affects the TiO2 surface and reduces open circuit photovoltage. The degradation effects were notably supressed by the use of the more stable EiPS solvent, where it was possible to optimize the iodine content in the redox mediator. It has been thus confirmed that iodine concentration as low as 0.05 M in the EiPS electrolyte is slightly preferable in terms of stability and device performance, comparing with higher concentrations, 0.1 and 0.15 M, respectively. © 2015 Elsevier Ltd. All rights reserved.