Carbon Materials and Technology
Zacharias Fthenakis; Antonios Fountoulakis; Ioannis Petsalakis; Nektarios Lathiotakis
Abstract
This work is part of a systematic study on the energy barriers for the permeation of several molecules, like He, H2, CO, CO2, H2O, NH3, CH4 etc, through nanoporous single layer graphene, having pores with different shape, size, and type. In the present work, we focus on the permeation of CO2 through ...
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This work is part of a systematic study on the energy barriers for the permeation of several molecules, like He, H2, CO, CO2, H2O, NH3, CH4 etc, through nanoporous single layer graphene, having pores with different shape, size, and type. In the present work, we focus on the permeation of CO2 through graphene pores which are constructed when neighboring carbon atoms of the graphene layer are removed from the structure, and nitrogen atoms have replaced the carbon atoms in the boundary of the pore. The energy barriers for each different pore are calculated using 2 different ReaxFF potentials along a path which the molecule would ideally follow in order to pass from the one side of the membrane to the other through the pore. Using the calculated values of the energy barriers, we estimate permeances by employing the kinetic theory of gasses. We give estimates for the preferable sizes and structures of the pores for permeability and demonstrate the ability of nanoporous graphene for CO2 separation.
Chen Xia; Muhammad Afzal; Baoyuan Wang; Aslan Soltaninazarlou; Wei Zhang; Yixiao Cai; Bin Zhu
Abstract
Very recently, natural hematite has been developed as an electrolyte candidate for solid oxide fuel cells (SOFCs), because of its considerable ionic conductivity. In this work, to exploit more practical applications of natural hematite, we report a novel mixed-conductive composite made of natural hematite ...
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Very recently, natural hematite has been developed as an electrolyte candidate for solid oxide fuel cells (SOFCs), because of its considerable ionic conductivity. In this work, to exploit more practical applications of natural hematite, we report a novel mixed-conductive composite made of natural hematite (α-Fe2O3) and semiconductor Ni0.8Co0.15Al0.05LiO2-δ (NCAL) to act as membrane layer in a new SOFC technology, electrolyte-layer free fuel cell (EFFC). The Hematite-NCAL composite was synthesized directly from natural hematite and commercial NCAL by solid-state blending and high-temperature calcination. The EFFC were constructed into a sandwich architecture with Hematite-NCAL as the membrane and NCAL pasted-Ni foams as the electrodes. Electrochemical impedance spectra (EIS) and direct current (DC) polarization measurements were carried out to investigate the electrical conductivity of the composite. A high ionic conductivity of 0.16 S cm -1 is achieved by the composite at 600 o C with mass ratios of 7:3 (7Hematite: 3NCAL). When operated at low temperatures, the as-designed fuel cell demonstrated superior power densities of 554 mW cm -2 at 600 o C and 342 mW cm -2 at 500 o C. Considering the competitive cost, abundant resource and eco-friendliness of natural hematite, our findings indicate the Hematite-NCAL can be a highly promising candidate for advanced low-temperature SOFC applications.
