Modification Of Biomass Carbon Materials And Its Application In Electrocatalysis

Energy is an important foundation and guarantee for economic and social development.In the past hundred years,the utilization of electric power has promoted the rapid development of human civilization.According to WWF data,90% of the world’s energy consumption is supported by fossil fuels.With the depletion of fossil resources,the world population has attracted more and more attention.Governments around the world are considering alternative and sustainable energy.Fuel cells have high thermodynamic efficiency,excellent load characteristics,fast response time,low pollution emission behavior,simplicity of mechanical engineering,good power / weight ratio and its modular structure,which make them have ideal flexibility in providing power.However,the high over potential and slow kinetics of the cathode inhibit its large-scale development.The movement of electrons in cathodic oxygen reduction reaction(ORR)is slow and complex.Therefore,for fuel cells,high-performance ORR electrocatalysts are related to whether they can develop in a large area in industry.Therefore,accelerating the reaction rate of ORR and improving the energy conversion efficiency of cells are of great significance for the development of new energy and the protection of the environment.Platinum and its alloys are considered to be excellent catalytic materials for the preparation of orr.However,Pt and Pt based materials also have some disadvantages that can not be ignored,such as high price,low abundance and poor tolerance to impurities.In order to solve the bottleneck problem of these precious metals and precious metal derived catalysts,people have carried out a lot of research on non precious metal catalysts.The synthesis of metal free carbon based electrocatalysts for ORR to replace the traditional platinum based catalysts has become a research hotspot.The synthesis of metal-free carbon-based electrocatalysts for ORR to replace conventional Pt-based catalysts has become a hot spot in current research.This work proposes an activationassisted carbonization strategy,to manufacture N-doped ultra-thin carbon nanosheets(GWS180M800)with high catalytic activity,namely,melamine is used as an accelerator/nitrogen source,and walnut green peels biological waste as carbon source.The melamine acts as a nitrogen donor in the hydrothermal process,effectively enhancing the nitrogen doping rate.The content of pyridine nitrogen groups accounts for up to 48.5% of the total nitrogen content.Electro-chemical tests show that the GWS180M800 has excellent ORR electrocatalytic activity and stability,and makes a quasi-four-electron ORR pathway clear in the alkaline electrolyte.The initial potential and half slope potential are as high as 1.01 and 0.82 V vs.RHE,respectively.The GWS180M800 catalyst has a better ability to avoid methanol cross poisoning than Pt/C has.Compared with 20 wt% Pt/C,GWS180M800 has improved methanol tolerance and stability.It is a metal-free biochar ORR catalyst with great development potential and application prospects.This result provides a new space for the preparation of valuable porous nano-carbon materials based on carbonaceous solid waste and provides new ideas for catalyzing a wide range of electrochemical reactions in the future.