Preparation Of Functional Carbon Materials And Their Catalytic Performance

Proton exchange membrane fuel cells(PEMFCs)can effectively convert chemical energy into electrical energy.Because of its high efficiency,high power density,and zero emissions,it is considered to be a promising mobile energy device in the future.The commercialization of PEMFCs needs to overcome some problems,such as high cost,low activity,and insufficient durability,among which electrocatalysts are considered to be the key to determining the cost and durability of PEMFCs.At present,it is reported that there are two ways to reduce the catalyst cost of PEMFC: one is to develop high-activity,high-stability oxygen reduction(ORR)catalysts based on non-precious metals;the other is to increase metal utilization and thus reduce the dosage of metals.In this dissertation,starting from the preparation of functional carbon carriers,the research on the construction of oxygen reduction catalysts based on carbon carriers was explored.The main contents are as follows:Part Ⅰ: Preparation of three-dimensional porous carbon material and its application in oxygen reduction catalysts.In this research work,Ketjen black EC-300 J,melamine,formaldehyde and other raw materials were used to synthesize high nitrogen content of three-dimensional carbon material Fe/NRC(nitrogen-rich carbon aerogel)through Pickering emulsion polymerization.During the characterization process,the morphology of EC-300 J,NRC,and Fe/NRC obtained at different carbonization temperatures were observed,the crystal structure was analyzed,and further the oxygen reduction catalytic performance was studied.The study found that its morphology is similar to that of a semi-open carbon nanocage showing a three-dimensional honeycomb structure;its catalytic activity is well;its stability is excellent.After 10,000 cycles,it is almost the same as the original ORR curve.After 20,000 cycles,the half-wave potential has only 2.804% attenuation.Part Ⅱ: Preparation of nitrogen-doped hollow carbon materials and their application in electrocatalytic oxygen reduction.In this work,the hollow carbon sphere(HCS)was first synthesized using a silica template method,in which liquid polyacrylonitrile(PAN)was used as a carbon precursor,and in the later functionalization,iron salts and EC-300 J were compounded to make Fe/HCS/C.Then,morphology analysis of its various stages of product,thermal analysis,Raman spectroscopy and oxygen reduction catalytic performance studies were completed.During the morphological characterization process,the carbon material HCS was found to have a diameter of about 120 nm.By adjusting the concentration of PAN and so on,the morphology of HCS was controlled to a certain extent,from high order to defects.Through analysis of the nitrogen adsorption-desorption curve,it was confirmed that all HCS contained only a very small number of micropores,most of which were mesopores and macropores.The Raman analysis showed that HCS is a partially graphitized carbon material.Subsequently,in the functionalization,Fe/HCS/C obtained by us has a considerable activity and stability,and we can try to improve it as a non-noble metal oxygen reduction catalyst with high performance in the future.