The Ti-Supported MnO_2 electrode was modified by introducing SnO_2+RuO_2+MnO_2 as an intermediate layer into the Ti/MnO_2 interface. The anodic polarization curves were measured at various temperatures ranging from 30...The Ti-Supported MnO_2 electrode was modified by introducing SnO_2+RuO_2+MnO_2 as an intermediate layer into the Ti/MnO_2 interface. The anodic polarization curves were measured at various temperatures ranging from 30 to 80℃ and the activation energy for the oxygen evolution reaction was evaluated. The experimental activation energy increased linearly with increasing the overpotential. The activation energy at the equilibrium potential was linearly correlated with the difference between the crystal field stabilization energies of Mn^(4+) at initial state and Mn^(4+) at transition state. The electrocatalysis characteristics of the anode were discussed by means of the mechanism of the substitution reaction of the ligand(S_N1 and S_N2) and molecular orbital theory. The results show that the anode has better electrocatalystic characteristics.展开更多
MnO2/MnO cathode material with superior Zn^2+storage performance is prepared through a simple physical mixing method.The MnO2/MnO nanocomposite with a mixed mass ratio of 12:1 exhibits the highest specific capacity(36...MnO2/MnO cathode material with superior Zn^2+storage performance is prepared through a simple physical mixing method.The MnO2/MnO nanocomposite with a mixed mass ratio of 12:1 exhibits the highest specific capacity(364.2 mA·h/g at 0.2C),good cycle performance(170.4 mA·h/g after 100 cycles)and excellent rate performance(205.7 mA·h/g at 2C).Analysis of cyclic voltammetry(CV)data at various scan rates shows that both diffusioncontrolled insertion behavior and surface capacitive behavior contribute to the Zn2+storage performance of MnO2/MnO cathodes.And the capacitive behavior contributes more at high discharge rates,due to the short paths of ion diffusion and the rapid transfer of electrons.展开更多
In this work,molybdenum disulfide quantum dots（MoS2 QDs） were firstly prepared by hydrothermal method using sodium molybdate and glutathione as precursors,and applied in ascorbic acid detection.When joining MnO2 nan...In this work,molybdenum disulfide quantum dots（MoS2 QDs） were firstly prepared by hydrothermal method using sodium molybdate and glutathione as precursors,and applied in ascorbic acid detection.When joining MnO2 nanosheets into MoS2 QDs solution,they produced an obvious fluorescence quenching,which should be due to inner filter effect（IFE）.Meanwhile,the fluorescent probe was formed,Interestingly,we found that this quenching phenomenon disappeared with the addition of ascorbic acid,In other words,the fluorescence gradually restored.This recovery phenomenon is mainly due to the reduction effect of ascorbic acid for MnO2 nanosheets.Under the optimum conditions,the limit of detection（LOD） of 39 nmol/L for ascorbic acid was achieved with a linear range of 0.33-5.00 μmol/L.The repeatability was better than 5.0% for ascorbic acid in both standard and fruit samples（n = 3）.Moreover,the as-fabricated fluorescent sensing system was successfully employed to detect the ascorbic acid levels in hawthorn and jujube with satisfactory results.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘The Ti-Supported MnO_2 electrode was modified by introducing SnO_2+RuO_2+MnO_2 as an intermediate layer into the Ti/MnO_2 interface. The anodic polarization curves were measured at various temperatures ranging from 30 to 80℃ and the activation energy for the oxygen evolution reaction was evaluated. The experimental activation energy increased linearly with increasing the overpotential. The activation energy at the equilibrium potential was linearly correlated with the difference between the crystal field stabilization energies of Mn^(4+) at initial state and Mn^(4+) at transition state. The electrocatalysis characteristics of the anode were discussed by means of the mechanism of the substitution reaction of the ligand(S_N1 and S_N2) and molecular orbital theory. The results show that the anode has better electrocatalystic characteristics.
基金Project(21905304)supported by the National Natural Science Foundation of ChinaProject(ZR2019BEM031)supported by the Natural Science Foundation of Shandong Province,ChinaProjects(18CX02158A,19CX05001A)supported by the Fundamental Research Funds for the Central Universities,China。
文摘MnO2/MnO cathode material with superior Zn^2+storage performance is prepared through a simple physical mixing method.The MnO2/MnO nanocomposite with a mixed mass ratio of 12:1 exhibits the highest specific capacity(364.2 mA·h/g at 0.2C),good cycle performance(170.4 mA·h/g after 100 cycles)and excellent rate performance(205.7 mA·h/g at 2C).Analysis of cyclic voltammetry(CV)data at various scan rates shows that both diffusioncontrolled insertion behavior and surface capacitive behavior contribute to the Zn2+storage performance of MnO2/MnO cathodes.And the capacitive behavior contributes more at high discharge rates,due to the short paths of ion diffusion and the rapid transfer of electrons.
基金financially supported by National Nature Science Foundation of China (No. 21475053)
文摘In this work,molybdenum disulfide quantum dots（MoS2 QDs） were firstly prepared by hydrothermal method using sodium molybdate and glutathione as precursors,and applied in ascorbic acid detection.When joining MnO2 nanosheets into MoS2 QDs solution,they produced an obvious fluorescence quenching,which should be due to inner filter effect（IFE）.Meanwhile,the fluorescent probe was formed,Interestingly,we found that this quenching phenomenon disappeared with the addition of ascorbic acid,In other words,the fluorescence gradually restored.This recovery phenomenon is mainly due to the reduction effect of ascorbic acid for MnO2 nanosheets.Under the optimum conditions,the limit of detection（LOD） of 39 nmol/L for ascorbic acid was achieved with a linear range of 0.33-5.00 μmol/L.The repeatability was better than 5.0% for ascorbic acid in both standard and fruit samples（n = 3）.Moreover,the as-fabricated fluorescent sensing system was successfully employed to detect the ascorbic acid levels in hawthorn and jujube with satisfactory results.
