Functionalization And Electrochemistry Of Dispersible Mesoporous Carbons Nanospheres

Mesoporous carbons (MPCs) are viewed as promising catalytic active materialsin the field of electrochemistry, owing to their large surface area, a porous structureand good conductivity, chemical stability, biocompatibility. For example, MPCs canbe used as catalyst or catalyst supports to confine catalyst particles. In addition, MPCscan be explored as anodic material of Li-ion. However, inactive and insoluble surfaceof MPCs limit their practical application in many fields. Mesoporous carbonnanospheres (MPCSs) are soluble as well as owing the feature of carbon material. Sothey will be widely used to preparing electrochemical sensors.Recently, N-doped mesoporous carbon material have been investigated.By donating a lone pair of electrons and shifting the neutralized chargedistribution on the carbon, nitrogen doping can modulate the electronicstructure and surface chemistry of carbon-based materials. The positive chargedensity on the adjacent C atom deriving from N doping can induce “activationregion” on the material surface, which may directly participate in catalyticreactions. The catalytic activity of each species depends largely on the surfaceand the amount of N. Large surface can provide a large number of carbon atomactive sites. N-doping may be responsible for the formation of a large numberof carbon atom active sites. However, excessive nitrogen doping interrupts theinterconnections of the graphitic structure and poisons more sites in carbonmaterials. A maximum nitrogen content range and activation temperatureshould exist, at which the effect of doping an additional electron is inoverwhelming superiority over disordering of the graphitic structural units.This work we have prepared series of dispersible N-doped porous carbonsnanospheres (NPCSs) with a high N content by using a low-molecular-weightsoluble resol and dicyandiamide (DCDA) as the carbon and nitrogen source. The compounds of rigid phenolic resin and DCDA were formed duringthermosetting, and subsequent they were pyrolyzed at different temperature inN2for carbonization. By using them to modify bare glassy carbon (GCE) forcatalyzing AA, UA and DA, we concluded that one material with large surfacearea, specific active sites, good accessibility and proper nitrogen showed highselectivity and sensitivity.In addition, we have also prepared S、N dual-doping phenolic resin carbonsnanospheres (S/N-PCSs) with DCDA and urea as nitrogen and sulfur source. Theresultant co-doped S/N-PCSs with large surface area, porous and high N, S content,manifest significantly enhanced electrocatalytic behavior with mainly four electrontransfer pathway in ORR in alkaline condition. Due to the synergistic contribution ofN, S doping and fast electron transfer rate offered by porous structure, S/N-PCSsshowed excellent catalytic activity. The calculations indicated that the co-doping of S,N may lead to the redistribution of charge densities and spin, which result in theformation of a large amount of active sites. Here we have used the same method aspreparing NPCSs, just for an additional source of sulfur. This is newly efficientapproach for the synthesis of heteroatom doped carbon materials. The presentpreparation method may supply an attractive and inspiring platform for preparation ofa series of tunable heteroatom-doped carbon materials for fuel cells and otherapplications.