Non-platnium Catalysts Derived From Biomass Materials For Low Temperature Fuel Cells

Low temperature fuel cells(LTFC)have attracted wide attention due to their low operation temperature,environmental friendliness,and high energy conversion efficiency.A critical issue in the commercialization of fuel cells is the development of highly efficient and cost effective catalysts for the sluggish oxygen reduction reaction(ORR)at the cathode.Hitherto,Pt and Pt-based alloys are known as the most efficient catalysts for ORR.However,the large scale implementation is heavily limited due to their high cost and scarcity.Moreover,the Pt-based catalysts also suffer from poor durability and easy to poisoning.Heteroatom-doped carbon materials have been recognized as promising candidates for ORR considering their worldwide availability,corrosion resistance,and environmentally friendly nature.Among various carbon-doped materials,the nitrogen-doped carbon materials exhibit the best oxygen reduction catalyst activity.Biomass,as a raw material in nature,is an ideal precursor for the preparation of nitrogen-doped carbon catalyst because of their widely available,low cost and no pollution to the natural environment properties.In this paper,we use biomass as precurser to prepare nitrogen-doped carbon catalyst for ORR in alkaline media with special morphology by thermal treatment and other methods.Firstly,frond biomass is used as precursor by hydrothermal carbonization,freeze-drying,high-temperature heat treatment under ammonia atmosphere and a series of post-processing to prepare nitrogen-doped carbon catalyst.The test results show that the catalyst prepared at 1000 ℃ not only has large specific surface area,but also has a high nitrogen content and reactive nitrogen(pyridine nitrogen)content,leading to the highest oxygen reduction activity under alkaline conditions,the onset potential is E0 =-0.016 V,the half wave potential is E1/2 =-0.15 V,which is comparable to that of Pt/C.Stability of the prepared catalyst is better than commercial platinum-carbon,and has excellent resistance to CO position and methanol oxidation.Besides,after preliminary carbonization,ball milling,KOH activation,acid leaching and second thermal treatment in ammonia,a 3D-graphene like nitrogen-doped carbon catalyst is successfully prepared by using cellulose biomass as precursor.KOH activation is benecifical for thr formation of 3D-graphene like structure,after KOH activation,the specific surface area is as high as 1756m2g-1.Larger specific surface area and porous structure can expose more active sites,and can also conduct the electrolyte into the interior of the carbon material to get in contact with the more active sites.The onset potential in 0.1 M KOH is-0.03 V,and half-wave potential is-0.17 V,which outperform that of Pt/C.The as prepared catalyst has better stability than Pt/C and is immune to CH3 OH oxidation and CO poison.Besides,compared with Pt/C,the ORR performace of the as prepared catalyst in acid media is good,and has better stability and is immune to CO poison.