Determination of isotope abundance for deuterium-labeled compounds by quantitative 1 H NMR + 2 H NMR.

Deuterated reagents have been used in many research fields. Isotope abundance, as the feature parameter of deuterated reagents, the precise quantification, is of great importance. Based on quantitative nuclear magnetic resonance technology, a novel method that combines 1 H NMR + 2 H NMR was systematically established to determine the isotopic abundance of deuterated reagents. The results showed that the isotopic abundance of partially labeled and fully labeled compounds calculated by this new method was even more accurate than that calculated by classical 1 H NMR and mass spectrometry (MS) methods. In brief, this new method is a robust strategy for the determination of isotope abundance in large-scale deuterated reagents.

Hierarchical Mn2O 3Hollow Microspheres as Anode Material of Lithium Ion Battery and Its Conversion Reaction Mechanism Investigated by XANES.

Hierarchical Mn2O3 hollow microspheres of diameter about 6-10 µm were synthesized by solvent-thermal method. When serving as anode materials of LIBs, the hierarchical Mn2O3 hollow microspheres could deliver a reversible capacity of 580 mAh g(-1) at 500 mA g(-1) after 140 cycles, and a specific capacity of 422 mAh g(-1) at a current density as high as 1600 mA g(-1), demonstrating a good rate capability. Ex situ X-ray absorption near edge structure (XANES) spectrum reveals that, for the first time, the pristine Mn2O3 was reduced to metallic Mn when it discharged to 0.01 V, and oxidized to MnO as it charged to 3 V in the first cycle. Furthermore, the XANES data demonstrated also that the average valence of Mn in the sample at charged state has decreased slowly with cycling number, which signifies an incomplete lithiation process and interprets the capacity loss of the Mn2O3 during cycling.