Morphology Control And Electrochemical Performance Of SmMn₂O₅ Nanocrystals

With environmental pollution and the excessive consumption of traditional energy,the application of new energy materials has become more and more important.The development of a new generation of energy storage and conversion systems is an important part of the application of new energy,recyclable fuel cells and the development of capacitive energy storage devices has attracted widespread attention.However,high cost and low energy density limit its application.Therefore,we need to find cheap,efficient,easily available non-noble metal catalysts to replace precious metal catalysts to achieve energy storage and conversion.In this work,different manganese sources are used to synthesize SmMn₂O₅ nanocrystals with different morphologies by hydrothermal synthesis,and the electrochemical performance is tested.First,SmMn₂O₅ nanoparticles and nanorods are synthesized using manganese acetate as a manganese source,and sea urchin-like and sheet-like SmMn₂O₅nanocrystals are synthesized using manganese nitrate as a manganese source,and their oxygen reduction catalytic performance and capacitor electrochemical performance were tested.Electrochemical test results show that sea urchin-like SmMn₂O₅nanocrystals has excellent oxygen reduction performance.Sheet-shaped SmMn₂O₅nanocrystals has shown great potential in capacitor applications.Secondly,sea urchin-like SmMn₂O₅ nanocrystals with different MnO₂ content are synthesized.The oxygen reduction test showed that the catalytic activity of sea urchin-like SmMn₂O₅ with a reaction time of 16 h is much higher than that of pure phase SmMn₂O₅ nanocrystals,and the half-wave potential reached 0.82 V（vs.RHE）.The peak power density of the zinc-air battery assembled with sea urchin-shaped SmMn₂O₅ reached 129.45 m W cm^-2,and the high cycle stability of 450 h is achieved.In the synthesis,MnO₂ was introduced into SmMn₂O₅ for the first time,and the effect of Mn³⁺and oxygen vacancies on the ORR catalytic activity of sea urchin-like SmMn₂O₅ nanocrystals was evaluated.Finally,the sheet-shaped SmMn₂O₅ nanocrystals are synthesized at different times and the electrochemical performance of the capacitor was tested.It was found that the specific capacity of the sheet-shaped SmMn₂O₅ nanocrystals with a reaction time of 20 h reached 334.25 Fg^-1.The maximum specific capacities that can be provided at a current density of 0.5 Ag^-1 is 178.4 Fg^-1,which is higher than that of sheet-like SmMn₂O₅ nanocrystals at other times and much higher than the reported capacitance of SmMn₂O₅.Our work provides ideas for the rational design of high-efficiency electrocatalysts and high-capacity capacitors.