Development of lithium-oxygen (Li-O 2 ) batteries is hindered by large overpotentials, low energy efficiency and unsatisfactory cycling life, which are predominately caused by the oxygen evolution reaction (OER) involving sluggish oxidation of lithium peroxide (Li 2 O 2 ). Herein, a highly-efficient soluble redox mediator (RM) of N , N’ -Diphenyl- p -phenylenediamine (DPPD) is introduced to catalyze the oxygen evolution reaction for Li-O 2 batteries. During charging process, DPPD is electrochemically oxidized into DPPD + , which can chemically decompose Li 2 O 2 on the cathode with a much-reduced overpotential. The in-situ differential electrochemical mass spectrometry confirms that the charging process is dominated by Li 2 O 2 decomposition. With the assistance of DPPD, Li-O 2 cells can achieve lower charging potential, improved cycling stability, and prolonged lifespan (294 cycles) which is three times longer than that of tetrathiafulvalene counterpart. This work presents a credible and viable opportunity for long lifespan Li-O 2 batteries.
Zhi Peng Cai,Andrew Kevin Hagan,Mao Mao Wang,Sabine Lahja Flitsch,Li Liu,Josef Voglmeir
We herein report the use of 1,3-di(2-pyridyl)-1,3-propanedione (DPPD) as a fluorogenic labeling reagent for sugars. Reaction of DPPD with the anomeric carbon affords a fluorescent 2-pyridylfuran (2-PF) moiety that permits the sensitive HPLC-based detection of monosaccharides. 2-PF-labeled monosaccharides can be easily separated and analyzed from mixtures thereof, and the reported protocol compares favorably with established labeling reagents such as 2-aminobenzoic acid (2-AA) and 1-phenyl-3-methyl-5-pyrazolone (PMP), ultimately allowing subfemtomole detection of the galactose-derived product. Furthermore, we demonstrate the application of DPPD in the labeling of monosaccharides in complex biological matrices such as blood and milk samples. We envisage that DPPD will prove to be an excellent choice of labeling reagent in monosaccharide and carbohydrate analysis.
危险品化学品经营许可证（带存储）