Search

Li2CO3 is the most tenacious parasitic solid-state product in lithium–air batteries (LABs). Developing suitable redox mediators (RMs) is an efficient way to address the Li2CO3 issue, but only a few RMs have been investigated to date, and their mechanism of action also remains elusive. Herein, we investigate the effects of the central metal ion in binuclear metal phthalocyanines on the catalysis of Li2CO3 decomposition, namely binuclear cobalt phthalocyanine (bi-CoPc) and binuclear cobalt manganese phthalocyanine (bi-CoMnPc). Density functional theory (DFT) calculations indicate that the key intermediate peroxydicarbonate (*C2O62−) is stabilized by bi-CoPc2+ and bi-CoMnPc3+, which is accountable for their excellent catalytic effects. With one central metal ion substituted by manganese for cobalt, the bi-CoMnPc's second active redox couple shifts from the second Co(II)/Co(III) couple in the central metal ion to the Pc(-2)/Pc(-1) couple in the phthalocyanine ring. In artificial dry air (N2-O2, 78:22, v/v), the LAB cell with bi-CoMnPc in electrolyte exhibited 261 cycles under a fixed capacity of 500 mAh g−1carbon and current density of 100 mA g−1carbon, significantly better than the RM-free cell (62 cycles) and the cell with bi-CoPc (193 cycles). [ABSTRACT FROM AUTHOR]

We bootstrap the 4-point amplitude of N = 2 hypermultiplets in AdS2 × S2 at tree-level and for arbitrary external weights. We hereby explicitly demonstrate the existence of a hidden four-dimensional conformal symmetry that was used as an assumption in previous studies to derive this result. [ABSTRACT FROM AUTHOR]

A novel method to prepare asymmetric amine ethers is reported. Tertiary amine alcohol hydrogen sulfate intermediates are prepared through a reactive distillation process, followed by the transesterification process to afford eventually asymmetric amine ethers. Experiments and DFT calculations revealed the essential roles the sulfate group plays in the highly selective monoesterification process. This clean method is tolerant towards various functional groups with good yields under mild condition, which is obviously superior compared to the conventional processes. [ABSTRACT FROM AUTHOR]

Gas-phase reactions of [LnO]+ with methane have been studied by using inductively coupled plasma-mass spectrometer (ICPMS) combined with quantum chemical calculations. Experiments indicate that the [LnO]+ (Ln=Sm-Lu) ions are able to activate methane to generate methyl radicals. In particular, [EuO]+ and [YbO]+ exhibit the highest reactivity. Interestingly, ab initio computations reveal a novel HAT process operating in the absence of a terminal oxygen radical, as mediated by [EuO]+ and [YbO]+. Such a process diverges from previous findings on the methane activation by metal oxide clusters, not only on the electronic pattern during the course of hydrogen transfer, but also on the important role that 4f electrons play. The associated electronic origins have been discussed, and the well-designed 4f electron occupation may turn to be a promising approach in constructing lanthanide involved catalysts. [ABSTRACT FROM AUTHOR]