Design And Synthesis Of Mesoporous Carbon Derived From Cyano-based Ionic Liquid As Efficient Bifunctional Electrocatalyst

Mesoporous carbon materials have been widely used in a variety of technological and energy-related materials fields.Recently,ionic liquids(ILs),an emerging family of carbon precursors,have attracted extensive attention because of their favorable properties such as intrinsic nonvolatility,non-flammability,high thermal and chemical stability,diverse cationanion combinations,facile synthesis/multiple element doping,and direct carbonization.As is well known,cyano-based ionic liquids inter-reaction is a key step for thermally stable and cross-linkable polymeric structures between molecule precursors and carbon materials.Nevertheless,this chemical process is argued to undergo intermediate nitrile cyclotrimerization reactions(NTR,i.e.nitrile-to-triazine transformation).The condensation and carbonization mechanism is not well understood due to the complexity of the pyrolysis process.In this thesis,we demonstrate a new nitrile chain reaction(NCR)during the condensation and carbonization process.We believe it will be a great progress on the condensation and carbonization process of cyano-based ionic liquids precursors.The new nitrile chain reaction(NCR)developed here is different from traditional NTR during the condensation and carbonization process.NCR drives several oligomers such as dimers,trimers and tetramers to undergo a variety of cross-linking and recombination steps to produce mesoporous carbon materials.A virtue of the cyano-based ionic liquids and NCR mechanism is that the produced mesoporous carbon material can be readily obtained with a specific surface area of 1050 m2 g-1,a high co-doping content with both nitrogen and sulfur,and a high degree of graphitization.In terms of potential applications,the N,S-codoped mesoporous carbon materials facilitate excellent bifunctional electrocatalytic activity toward the oxygen reduction and oxygen evolution reactions comparable to those of commercial 20 wt% Pt/C and Ru O2 catalysts,respectively.Moreover,our analyses show that the anions of cyano-based ionic liquids display much better thermal stability than imidazolium cations,which might inspire others to develop different functional cations for more thermally stable intermediate polymeric structures in the future.