Construction And ORR Performance Investigation Of Rare-earth Carbide Composite Catalytic System

Precious metals are the most ideal among plenty of fuel cell catalysts.However,their high cost and resource-constrained have become obstacles for the large-scale manufacture of fuel cells.Therefore,it is extremely urgent to develop highly active and low cost of catalysts in fuel cell.So far,some non-noble metal catalysts have showed many advantages in fuel cell applications,such as high catalytic activity,good stability and excellent resistance to permeate organic small molecules.In particular,metal carbide composite catalyst has great potential as non-precious metal to realize the commercialization of catalysts.In addition,since rare-earth elements have various catalytic properties,many rare-earth elements have been used to prepare catalysts and have obtained satisfactory results.However,the research on rare-earth metal carbide is scarce.So the application of rare-earth carbide composite catalyst to the cathode oxygen reduction is one of the feasible ways to realize the commercialization of fuel cell.Therefore,the thesis mainly focuses on the preparation of high efficiency and low cost catalysts.Rare-earth metal carbides are used as the starting point and recombined nitrogen doped carbon material.In these three parts,the structures of as-prepared catalysts were characterized by physical measurements.And their electrocatalytic performance was also studied by electrochemical test methods.The thesis consists of three parts as follows: Part I: Preparation of embedded cerium carbide composite catalyst and application of oxygen reduction reactionMetallic carbides exhibit catalytic activity similar to precious metals due to the presence of d-band electron density resemblance that of precious metal.In this section,the nitrates of melamine formaldehyde resin and rare-earth elements were selected as the reaction precursor,and embedded carbide cerium(Ce Cx-NC)composite catalyst was prepared by high temperature carbonization.The catalytic performance of ORR in alkaline medium was studied.The prepared catalyst shows high electrocatalytic activity towards ORR,with the half wave potential being almost equal to commercial Pt/C,nearly 4e-transfer number,good toxicity tolerance durability and cycle stability.This rare-earth metal carbide opens a novel avenue for advanced electrocatalyst.Part II: Dry process preparation of rare-earth bimetallic carbide composite catalyst and application of oxygen reduction reactionRare-earth bimetallic carbides not only have general characteristics of metal carbides,but also have some special properties.Such as,they have intrinsic stability and the synergy effect between different metals.In this part,rare-earth bimetallic carbide composite catalyst was prepared as ORR catalyst by a preparation way of solid phase grinding.It showed that cerium and lanthanum mass ratio of 1:2,carbonization temperature of 1000 ? is optimal ratio and temperature.NC-Ce La2Cx-1000 catalyst has good catalytic performance towards ORR.It possesses stronger resistance to toxicity and stronger cyclic stability than commercial Pt/C catalyst.Rare-earth bimetallic carbides composite catalyst will be a promising ORR catalyst.Part III: Wet process preparation of rare-earth bimetallic carbide composite catalyst and application of oxygen reduction reactionSimple and efficient catalyst preparation method is also crucial for the development of fuel cell.In this part,a simple liquid reaction method is used to prepare rare-earth bimetallic carbide as ORR catalyst.Ce La2Cx-NC has been prepared by a facile pyrolysis of o-phthalic anhydride,melamine and rare-earth elements(Ce and La).The prepared Ce La2Cx-NC electrocatalyst shows satisfactory electrocatalytic activity towards ORR in alkaline electrolyte,as well as good suffering from methanol and CO poisoning,and superior stability than commercial Pt/C.It demonstrates that this simple preparation way would provide a neoteric avenue for the development of ORR catalyst.