0000000000608656
AUTHOR
Jamal Elhaskouri
The Li Ni0.2Mn0.2Co0.6O2 electrode materials: A structural and magnetic study
Graphical abstract: EPR signal of the Li{sub 0.6}Co{sub 0.6}Ni{sub 0.2}Mn{sub 0.2}O{sub 2} composition showing that Mn{sup 4+} ions are the solely paramagnetic ions in the structure. Highlights: Black-Right-Pointing-Pointer LiCo{sub 0.6}Ni{sub 0.2}Mn{sub 0.2}O{sub 2} was prepared by the combustion method with sucrose as a fuel. Black-Right-Pointing-Pointer Chemical delithiaition was performed by using NO{sub 2}BF{sub 4} oxidizing agent. Black-Right-Pointing-Pointer The rhombohedral symmetry was preserved upon lithium removal. Black-Right-Pointing-Pointer Lithium extraction leads to Ni{sup 2+} oxidation to Ni{sup 4+} followed by Co{sup 3+} oxidation. Black-Right-Pointing-Pointer The EPR narr…
Magnetic and structural approach for understanding the electrochemical behavior of LiNi0.33Co0.33Mn0.33O2 positive electrode material
Abstract A systematic study has been performed to investigate the structural and magnetic changes in LiNi 0.33 Mn 0.33 Co 0.33 O 2 , a member of the LiNi y Mn y Co 1–2 y O 2 series, upon chemical lithium deintercalation. Structural characterization of the chemically delithiated Li x Ni 0.33 Mn 0.33 Co 0.33 O 2 samples indicates that the initial rhombohedral symmetry (α-NaFeO 2 type structure) is maintained in the whole 0.3 ≤ x ≤ 1.0 composition range. Less than 1% variation in the hexagonal unit cell volume was evidenced showing a good structural stability of this sample. SEM pictures of the delithiated phases confirm this stability. Indeed, the particle size average undergoes a small dec…
Oxidative dehydrogenation of isobutane over Co-MCM-41 catalysts
Abstract Cobalt-containing mesoporous silicates with MCM-41-like structure, with Si/Co≥49, are active and selective catalysts for the oxidative dehydrogenation (ODH) of isobutane. The formation of dehydrogenation products is analysed in terms of the nature of the cobalt species, tetrahedral Co(II), and heterogeneously initiated gas-phase reactions inside the mesopores.
Total oxidation of VOCs on Au nanoparticles anchored on Co doped mesoporous UVM-7 silica
Abstract Gold deposited on a cobalt containing siliceous mesoporous structure, UVM-7, presents a good catalytic performance in the total oxidation of propane and toluene. The presence of both gold and cobalt is necessary as bimetallic Au/Co-UVM-7 catalysts are remarkably more active than monometallic Au/UVM-7 or Co-UVM-7 catalysts. The improved activity of the bimetallic AuCo-samples if compared to gold free cobalt catalysts can be explained on the basis of the enhanced reducibility of some cobalt species in the presence of gold, which facilitates the redox cycle. This high reducibility of cobalt species in the bimetallic samples is probably due to the formation of Co 3 O 4 domains at the g…
Direct oxidation of isobutane to methacrolein over V-MCM-41 catalysts
High vanadium content mesoporous vanado-silicates with MCM-41-like structure, obtained by the atrane route, catalyse the direct oxidation of isobutane to methacrolein with 30% selectivity, and a total dehydrogenation (olefin plus methacrolein) selectivity up to 74%.