Graphene Nanosheet-Wrapped Mesoporous La0.8Ce0.2Fe0.5Mn0.5O3 Perovskite Oxide Composite for Improved Oxygen Reaction Electro-Kinetics and Li-O2 Battery Application.

A novel design and synthesis methodology is the most important consideration in the development of a superior electrocatalyst for improving the kinetics of oxygen electrode reactions, such as the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in Li-O2 battery application. Herein, we demonstrate a glycine-assisted hydrothermal and probe sonication method for the synthesis of a mesoporous spherical La0.8Ce0.2Fe0.5Mn0.5O3 perovskite particle and embedded graphene nanosheet (LCFM(8255)-gly/GNS) composite and evaluate its bifunctional ORR/OER kinetics in Li-O2 battery application. The physicochemical characterization confirms that the as-formed LCFM(8255)-gly perovskite catalyst has a highly crystalline structure and mesoporous morphology with a large specific surface area. The LCFM(8255)-gly/GNS composite hybrid structure exhibits an improved onset potential and high current density toward ORR/OER in both aqueous and non-aqueous electrolytes. The LCFM(8255)-gly/GNS composite cathode (ca. 8475 mAh g-1) delivers a higher discharge capacity than the La0.5Ce0.5Fe0.5Mn0.5O3-gly/GNS cathode (ca. 5796 mAh g-1) in a Li-O2 battery at a current density of 100 mA g-1. Our results revealed that the composite's high electrochemical activity comes from the synergism of highly abundant oxygen vacancies and redox-active sites due to the Ce and Fe dopant in LaMnO3 and the excellent charge transfer characteristics of the graphene materials. The as-developed cathode catalyst performed appreciable cycle stability up to 55 cycles at a limited capacity of 1000 mAh g-1 based on conventional glass fiber separators.

Electrical and Physical Characteristics of WO3/Ag/WO3 Sandwich Structure Fabricated with Magnetic-Control Sputtering Metrology †.

In this work, three layers of transparent conductive films of WO3/Ag/WO3 (WAW) were deposited on a glass substrate by radio frequency (RF) magnetron sputtering. The thicknesses of WO3 (around 50~60 nm) and Ag (10~20 nm) films were mainly the changeable factors to achieve the optimal transparent conductivity attempting to replace the indium tin oxide (ITO) in cost consideration. The prepared films were cardinally subjected to physical and electrical characteristic analyses by means of X-ray diffraction analysis (XRD), field-emission scanning electron microscope (FE-SEM), and Keithley 4200 semiconductor parameter analyzer. The experimental results show as the thickness of the Ag layer increases from 10 nm to 20 nm, the resistance becomes smaller. While the thickness of the WO3 layer increases from 50 nm to 60 nm, its electrical resistance becomes larger.