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Research Papers

J. Electrochem. En. Conv. Stor.. 2019;17(1):011001-011001-8. doi:10.1115/1.4043490.

The entire world is facing a great shortfall in the energy supply due to the high consumption rate of fossil fuel-based energy resources. Solid oxide fuel cells (SOFCs) are the best alternative energy devices, which convert hydrogen fuel directly into electricity. Alkali carbonated calcium-doped ceria electrolytes (LNK-CDC) as (Ce0.8 Ca0.2), (Ce0.7 Ca0.3), and (Ce0.6 Ca0.4) were synthesized by the co-precipitation method. With the addition of alkali carbonate, nanocomposites of ceria are well preserved after sintering at 600–700 °C. The structural and morphological properties were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Crystallite sizes were found in the range of 50–80 nm. The maximum ionic conductivity of LNK-CDC (Ce0.8Ca0.2) was achieved to be 0.14 S/cm at 650 °C for anion vacancy migration by the dense microstructure. The minimum activation energy was determined to be 0.23 eV. The Fourier-transform infrared spectroscopy (FTIR) spectra of the prepared materials show the absorbance of IR and their behavior. The maximum power density of symmetric fuel cells LNK-CDC sandwiched with LNCZ oxide electrodes was recorded as 0.52 W cm−2 at 650 °C in the presence of hydrogen (fuel). It is suggested that coating of the equal molar ratio of ternary alkali metals on ceria doped comparatively enhance the performance of new nanocomposite electrolyte for SOFC and other energy applications.

Commentary by Dr. Valentin Fuster
J. Electrochem. En. Conv. Stor.. 2019;17(1):011002-011002-5. doi:10.1115/1.4043491.

The green energy production through water splitting under visible light irradiation has become an emerging challenge in the 21st century. Photocatalysis, being a cost-competitive and efficient technique, has grabbed much more attention for environmental applications, especially for hydrogen evolution. In this article, the hybrid Cu3V2O8-WO3 nanostructures were prepared through the hydrothermal method by using copper acetate, ammonium metavanadate, and Na2WO4 · 2H2O as precursors. The varying contents of Cu3V2O8 in WO3 were 0.2%, 0.5%, 1.0%, 2.0%, and 3.0%. The X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), UV-Vis, and photoluminescence (PL) emission spectroscopy were used to investigate the structural, morphological, surface area, and optical properties of prepared samples. The average crystalline size of the pure WO3 ranges from 10 to 15 nm and 70 to 195 nm for an optimal composite sample. The structural phase of the hybrid WO3-Cu3V2O8 nanoparticles was found to transfer from monoclinic to hexagonal by incorporating the Cu3V2O8 contents. The enhanced photocatalytic performance for hydrogen evolution was observed for 2% Cu3V2O8-WO3 composite sample. The key to this enhancement lies at the heterojunction interface, where charge separation occurs. In addition, the excellent photocatalytic activity was attributed to a higher surface area, efficient charge separation, and extended visible light absorption. This work provides an in-depth understanding of efficient separation of charge carriers and transfer processes and steer charge flow for efficient solar-to-chemical energy applications.

Commentary by Dr. Valentin Fuster
J. Electrochem. En. Conv. Stor.. 2019;17(1):011003-011003-6. doi:10.1115/1.4043538.

The increasing use of electrical vehicles aroused the problem of batteries charging and the consequent interface with the power grid. Commercial charging solutions are mostly based on unidirectional power flow converters; however, bidirectional power flow converters are an interesting solution when considering smart microgrid applications, with benefits in efficient energy use. In this context, the paper presents a bidirectional power flow converter for grid-to-vehicle (G2V) or vehicle-to-grid (V2G) applications. The conversion system is based on a three-phase voltage source inverter (VSI), which assures the grid connection with a unitary power factor. The direct current (DC) bus of the voltage source inverter is connected to a DC/DC converter that controls the battery power flow. This conversion system can operate in G2V mode when charging the battery or in V2G mode when working as an energy storage system and the power flow is from the battery to the power grid. The conversion system model is presented as well as the control strategy proposed. Simulation and experimental results showing voltages and currents in the circuit are also presented.

Commentary by Dr. Valentin Fuster

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