Preparation Of Transition Metal Doped Carbon Based Materials And Application Of Electrocatalytic Oxygen Reduction

With the increasing consumption of energy,the serious shortage of traditional fossil fuels and the resulted environmental pollution,developing clean energy technologies with zero pollution and high energy conversion efficiency is becoming paramount.Electrocatalysis reactions,as an important process of energy storage and conversion devices,such as fuel cells,metal-air batteries and electrolysis of water,have become the focus of increasing research.Although precious-metal catalysts(such as Pt,Ir,Rh)have exhibited excellent catalytic performance,the high cost,scarcity and poor long-term stability greatly hinder the large-scale commercialization.Therefore,searching the cheaper electrocatalysts to replace precious metals is one of the hot topics of current research.In this thesis,based on the major scientific issues of electrocatalysis,we prepared a series of excellent ORR electrocatalysts through synthesis and regulation of transition metal doped carbon-based materials.The main research contents and innovation are summarized as follow:1.On the basis of the concept and composition of COFs,we developed a facile and effective method to prepare a Fe-N-rich precursor with the aid of silica nano-spheres as the controllable template.Followed by carbonization and chemical etching,the as-obtained hollow nanoshell catalyst HNS-800 possessed high specific surface areas and porosity,and exhibited excellent ORR performance both in acid and alkaline media.2.We synthesized a soluble two-dimensional(2D)quasi-phthalocyanine iron material with high density single atom active site via a microwave process,followed by composite with graphene through a wet grinding process.This process enhanced the conductivity,electronegativity and channel structure of the catalyst,etc,and further making full use of the uniform Fe-N4 active sites.On the premise of non-carbonization,a series of high performance ORR catalysts were obtained,and the SAS-Fe/G-0.2exhibited excellent ORR reactivity with an ultra-high half-wave potential of 0.91 V in 0.1 M KOH solution,which was far more than that of commercial Pt/C and other non-precious metal catalysts.3.Benefiting from the superior ORR performance of SAS-Fe/G-0.2 composite catalyst,a Zn-Air battery assembled with SAS-Fe/G-0.2 as ORR catalyst showed higher discharge voltage,power density and cycling stability compared with commercial Pt/C catalyst.Furthermore,the as-obtained SAS-Fe/G-0.2 catalyst also exhibited excellent discharge performance in the assembled all-solid-state(ASS)flexible and button cells.