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Quantitatively elucidating the reaction kinetics of Li–sulfur (Li–S) batteries is always crucial in optimizing cathode structures but challenging as well. Herein, we study and compare the reaction mechanism and kinetics of Li–S batteries via operando X-ray diffraction (XRD) and quantitative analysis based on several cathode structures. Operando XRD indicates that β-S8 has different nucleation orientations on MnO2 and carbon surfaces due to the different surface free energies. The quantitative analysis reveals that polysulfides encapsulated in MnO2 nanosheets result in fast Li2S and β-S8 nucleation in the discharge and charge processes, respectively. It also shows that open-hollow S@MnO2 exhibits faster S consumption and higher sulfur utilization than the solid core–shell S@MnO2 and carbon black/S. Our work provides deep insight into the reaction mechanism and kinetics of Li–S batteries and indicates that the cathode structures and host materials play critical roles in enhancing the reaction kinetics. [ABSTRACT FROM AUTHOR]

A facile generic strategy of combining template assisted and solvothermal alcoholysis is employed to prepare cage-bell Pd@CeO2 nanoparticle aggregates as catalysts for the low-temperature oxidation of CO. The synthetic parameters are regulated to control the size of the as-prepared CeO2 mesospheres. The activities of Pd@CeO2 catalysts are higher than that of Pd supported on Al2O3, and the activity of 1 wt% Pd@CeO2 can be further improved and its T90 is 2 °C. The intrinsic cage-bell nature as well as high porosity of the unique nanostructures of the CeO2 support contributes greatly to the formation of large numbers of surface oxygen vacancies on Pd@CeO2 catalysts, and thus it exhibits superior catalytic activity. This method is simple, low cost, mass-productive, and can also be used to prepare other advanced functional materials. [ABSTRACT FROM AUTHOR]