Preparation Of Graphene Derived From Biomass And Its Catalysis Towards Oxygen Reduction Reaction

Low-temperature fuel cells,for the high energy efficiency,low pollution,high safety andwide fuel source,are considered to be one of the most potential applications of new energy technology in the 21st century.At present,platinum is used as catalyst in the low-temperature fuel cells,but it has a series of problems.Besides limited resources,it is expensive and unstable,which are serious impediment for fuel cells'promotion and application.Therefore,it is of great significance to develop cheap non-platium catalysts to replace the expensiveplatinum based catalysts in the market.Nitrogen doped-graphene/porous grapheneis the first choice for non-platium catalysts of fuel cells,for their high specific surface area,good thermal and electrical conduction,and high stability.However,a large scale method of preparaing nitrogen doped-graphene/porous graphene is still lacked for the high cost and complex preparation technology used now.To slove such problems,we used biomass materials to prepare cheap nitrogen-doped porous graphene materials and fuel cells'catalysts.It is a new stragedy for large scale preparing graphene materials and the catalyst has a big potential to replace noble metal based catalysts and reduce the cost of fuel cells.We first choose porous leguminosae biomass,with rich nitrogen and plant fibre,as a presucor to prepare nitrogen-doped porous grapheneby carbonlized,ball milling with KOH,activation at high temperature and post-treated in ammonia.As-prepared graphene possesses high specific surface area?1152m²/g?,a large amount of structural mesopores,rich surface defects and effective nitrogen content?3.12 at%?.In alkaline media,the onset potential?E₀=^-0.009 V,vs.SCE?and half-wave potential(E_1/2=^-0.202 V)of the graphene catalyst is closed to that of 20 wt%commercial Pt/C(E₀=^-0.007 V,E_1/2=^-0.188 V).Also,it shows a better stability and immunity for metchanol?CH₃OH?crossover and carbon monoxide?CO?poisioning than that of Pt/C.In acidic media,the catalyst shows a lower ORR activity and a superior stability and CO tolerance than Pt/C catalyst.And inspired by excellent graphene structure and high ORR performance of catalyst prepared by KOH activated carbon derived from biomass materials and as a continuation of our research interests in graphene structure catalyst,we further used nightshade as a presucor,carbon source and a self-template to prepare graphene.After soaking KOH enough,then heat treatment and post-treated in ammonia,the nitrogen-doped porous graphene can be obtained.The preparedgraphene shows 3⁵layers,ultrahigh surface area?1969m²/g?and a number of defects.Also,the graphene has a little impedance?51??.As the ORR catalyst,the half-wave potential shows a 10mV positive than that of Pt/C in alkaline media and close to that of Pt/C in acidic media.In addition,the catalyst shows a higher stability,CH₃OH and CO tolerance than Pt/C catalyst.