Synthesis Of Nitrogen Doped Porous Carbon With Hollow/Macoporous Structure For CO₂ Capture And Oxygen Reduction Reaction

Porous carbon materials have been used in many fields owing to the attractive chemical and physical features,especially in the field of environment and energy.Active sites and porosity are the key issues affect the performance of porous carbon materials.Many reports have clarified that incorporate nitrogen heteroatom could promote the performance of porous carbon materials in the field of sorption,energy storage and conversion.At the meantime,high porosity is always pursued for many applications.Template and activate agents which involves strong corrosive agents are always needed to get high porosity,and it is even more complicate to get novel structures e.g.hollow structure and 3D structure.Thus its still great chanllage to fabricate novel porous carbon structures through general and effective strategies.The main results and discussion are as follows.1?One-step carbonization route was developed to get Nitrogen-doped Porous Carbon Hollow Spheres?N-PCHSs?using a melamine-formaldehyde?MF?nanosphere both as hard template and nitrogen source,and resorcinol-formaldehyde?RF?resin as a carbon precursor.When carbonizing the MF@RF spheres under an Ar atmosphere,the internal MF core decomposed into N-rich gas while the external RF shell transformed into a porous carbon framework,thus hard template could be removed through calcination.Importantly,with slow effusion of the N-rich gas from the interior,the nitrogen atom was effectively introduced into the outer carbon matrix,resulting in N-PCHSs.Owing to the activation process of the decomposed gases,the obtained N-PCHS showed abundant pores,a high surface area(775 m² g^-1)with an ultrahigh nitrogen content and thus exhibited considerable CO₂ sorption performance.2?Gas blowing and a coordination complex assembling were integrated to fabricate 3D metal–organic chelate foams.Subsequently,direct pyrolysis of the 3D chelate foams gave 3D nitrogen-doped carbon foams?NCFs?,the zinc oxide?ZnO?formed during the pyrolysis process served as a porogen for generating mesopores,and the reduced Zn vapor could also activate the carbon framework to further develop porosity.Therefore,the total solvent-and template-free process also gives NCFs with3D architecture,well-developed porosity and controllable pore structure,which can be further altered to be a unique mesopore-in-macropore structure by simply adjusting the ratio of nitrate to organic ligand.And the 3D NCFs also showed excellent performance in oxygen reduction reaction.3?We extend the solid assembly strategy in to a series of more common organic molecules i.e.amino acids.Amino acids are organic compounds containing amine?-NH2?and carboxyl?-COOH?functional groups,along with a branched chain?R group?specific to each amino acid.Amine?-NH₂?and carboxyl?-COOH?functional groups are considered as coordinate sites which will mainly contribute to the assembly,but the final porous carbons also affected significantly by the branched groups.We clarify the influence of precursor to the resultant carbons and proved that this solid assembly strategy is a general strategy towards 3D nitrogen doped graphic scaffolds.4?A series of nitrogen doped mesoporous carbon was obtained by choosing radish as carbon source,and KOH or ZnCl₂ as activate agents.Self-activation effect endows radish derived carbon high porosity even without any additives.But much improved porosity with more mesopores could be obtained through chemical activation.KOH activated carbon showed ultra-high surface area but with bottle-neck structured mesopores and decreased nitrogen content which results in poor ORR activity.However ZnCl₂ activated carbon could show both high porosity and high dopant content,thus it showed high activity towards ORR.