Synthesis Of Metal Oxide/Carbon Composites With Metal–organic Frameworks As Precursor And Their Electrochemical Applications

In recent years,with the consumption of fossil energy and climate change,and explore the social demand more and more attention is paid to the sustainable and renewable energy,including fuel cell and supercapacitor as the representative of the clean energy has aroused people's concern.The cathodic oxygen reduction reaction?ORR?is one of the most important factors limiting the commercialization of air fuel cells.Therefore,it is the main factor to promote the commercialization of fuel cells to find efficient and stable ORR catalysts.For supercapacitor,electrode material and electrolyte are the key factors to determine the performance of supercapacitors.Therefore,it is the key factor for the commercialization of supercapacitors to find electrode materials with large specific capacity.In the previous reports in the electrode material is a transition metal oxide,and cerium is???group sub group of periodic classification,have similar structure to transition metal and 3⁺and 4⁺cerium oxidation reduction,which has good prospects in the reduction of oxygen and supercapacitor applications.The main contents are divided into two parts:?1?the effect of carbonization temperature on the electrochemical properties of Ce-MOF-808?MOF?.?2?the influence of the morphology of the metal organic frameworks on the electrochemical performance.?1?Using ceric ammonium nitrate and three formic acid as the precursor,synthesized Ce-MOF-808 by hydrothermal method,the MOF was carbonized in Ar atmosphere,the carbonziation temperature was 400?.600?and 800?.With the increase of temperature,the higher the degree of carbonization,the better the conductivity.The calcined samples were placed in 0.1M KOH and 3M KOH to test the electrolyte oxygen reduction and supercapacitor performance,through the experiment,when the calcination temperature is 800 degrees centigrade,the composite ORR initial potential maximum?0.86?,supercapacitor than the maximum capacity?430F/g?.?2?Using cerium nitrate and all three formic acid as the precursor,through the method of stirring and static synthesis different morphology of Ce?1,3,5-BTC??H₂O?₆,carbonization at 800?under Ar atmosphere forming a composite material of CeO₂ and carbon,and do ORR and supercapacitor test.The test results showed that when MOF morphology is more dispersed nanorods,the initial potential ORR and supercapacitor performance best,this is because when MOF is more dispersed,is conducive to the electrolyte and the active material contact,thereby increasing the active area,enhanced electrochemical activity.