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Fe-doped layered P3-type K0.45Mn1-xFexO2 (x <= 0.5) as cathode materials for low-cost potassium-ion batteries
No full textA series of iron-substituted layered P3-type manganese oxides, K0.45Mn1-xFexO2 (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) were fabricated using a convenient solid-state method and studied as cathode materials for potassium-ion batteries. The microstructure and morphology of the as-synthesized materials were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. The electrochemical characteristics of K0.45Mn1-xFexO2 samples have been investigated systematically and K0.45Mn0.8Fe0.2O2 shows the best cyclic stability and highest rate performance. It delivers a large reversible discharge capacity of 106.2 mAh g(-1) at 20 mA g(-1) with a capacity retention rate of 77.3% after 100 cycles. It also presents obviously enhanced rate performance with the capacity of 64.9 mAh g(-1) at 200 mA g(-1) and stable cycling capability of 44.7 mAh g(-1) after 100 cycles. The results demonstrate that the relatively small substitution (20%) at the transition metal site can improve the cycle stability during potassium ions insertion and extraction. Therefore, the layered P-3-K0.45Mn0.8Fe0.2O2 possibly serves as a potentially promising cathode material that made from completely earthabundant elements for potassium-ion batteries applications
Qinhuangdao City University student of Science and Technology Innovation and Entrepreneurship Project[PZB1810008T-14]
No full textParticulate Oxynitride Photoanodes Assembled with Transparent Electron-Collecting Oxide Nanorod Arrays
No full textThe collection of photogenerated electrons is commonly a bottleneck in photoelectrochemical water oxidation on a particulate photoanode. Herein, a new strategy called "array insertion" for particulate photoanode preparation is proposed to improve electron collection. ZnO nanorod arrays are inserted between LaTiO2N particles and Al-doped ZnO (AZO) substrates via epitaxial electrodeposition, which make electronic connections. Using this methodology, charge separation efficiency is improved drastically, and the photocurrent at 1.23 V-RHE is enhanced by more than 1 order of magnitude, because the obstacle of electron collection in the particulate LaTiO2N photoanodes is overcome
Purification of tertiary and quaternary alkaloids from Rhizoma Corydalis using reversed-phase/weak cation-exchange mixed-mode class separation combined with preparative C18 and silica based strong cation-exchange chromatography
No full textA new optimization strategy for purification of alkaloids from Rhizoma Corydalis using preparative liquid chromatography was developed, featuring a selective separation of different types of alkaloids into different parts by a reversed-phase/weak cation-exchange mixed-mode column (named C18WCX) at first. The total alkaloids of Rhizoma Corydalis were divided into four fractions with fraction III and IV corresponding to the tertiary type medium bases and the quaternary type strong bases, respectively. For fraction III, a conventional C18 column was used to isolate tertiary alkaloids using acetonitrile and 0.1% phosphoric acid (adjusted with triethylamine to pH 6.0) as mobile phases. High selectivity and symmetrical peak shapes of tertiary alkaloids were obtained, resulting in six main tertiary alkaloids isolated in a single run. As strong bases, quaternary alkaloids often suffer from serious peak tailing problem on conventional C18 columns. Therefore, a silica-based strong cation-exchange (SCX) column was used for purification of fraction IV. On the SCX column, good peak shapes in high sample loading were achieved. Five main quaternary alkaloids were isolated and identified from the fraction in one-step. The procedures presented effective for the preparative isolation and purification of alkaloids from Rhizoma Corydalis
