Preparation And Performance Of Oxygen Evolution Reaction Of Hierarchical Porous Activated Carbon

Hydrogen has a quantity of excellent characters,such as outstanding thermal conductivity,environment friendly,a rich source,etc.Thus the hydrogen producing device—water splitting process induces great attention.The two halt-reaction exert in water splitting system is the oxygen evolution reaction?OER?and the hydrogen evolution reaction?HER?.The high overpotential and the low efficiency for electrochemical catalyst in OER limits the yield of hydrogen in the reaction of electrochemical splitting of water.It is very significant to investigate the new type of OER catalysts,which conduce to enhance the efficiency of hydrogen and solve the problem of energy shortage.Up to now,the most popular catalysts are those noble metal materials?Ru,Ir?,non-noble metal materials?Co,Ni based catalysts?and some carbon materials?carbon nanotube,graphene,etc.?.There are rare reports about the activated carbon applied in OER.In this thesis,we prepare the porous activated carbon materials and evaluate their OER activity by the electro-chemical data in OER.Hierarchical porous activated carbon?HPAC?shows potential applications for the OER.HPAC derived from fallen leaves?Fraxinus chinensis?is prepared using a facile method,in which KOH and/or K₂CO₃ are used as activators.Characterization reveals that HPAC in the system of KOH/K2CO3 has a high surface area and possesses abundant hierarchical pores,which are favorable for mass transfer and charge transfer in the OER.The potential in the 10 mA cm^-2 current density of the obtained HPAC is 1.596 V vs.RHE.Acid washed HPAC displays relatively low activity and electrochemical tests demonstrate that ash composition may contribute to the OER.HPAC is a potential carbon-based catalyst that has prominent OER activity and durability.We use the fallen leaves,cotton straws,pine needles,reeds and grass as the biomass materials,the same activator?KOH and K2CO3?and the same process of activation to produce the porous biomass activated carbon materials.Then applied them in OER,compare their differences and OER activity.The experiment reveals that HPAC derived from fallen leaves possess the best activity,because its abundant hierarchical porous,high activity sites,plenty of oxygen-containing functional groups and some trace elements.