The Preparation And Properties Of Biomass Based Non-noble Metal Electrocatalysts For Oxygen Reduction

The oxygen reduction reaction?ORR?of cathode which is a vital step of proton exchange membrane fuel cell?PEMFC?due to its sluggish kinetics,so it is of great significance to select appropriate ORR catalyst for PEMFC.Although Pt/C are commonly used in ORR for its excellent activity,the high cost,limited source,poor stability and bad tolerance of methanol limited their commercialization and wide application.So,it has strong significance to explore non noble metal ORR catalyst with ideal performance.Biomass act as carbon source owing advantage such as wide source,low price and environment friendly.Research and develop biomass derived carbon is a hotpot in current situation.We utilize simple approach and green raw materials to prepare catalyst with outstanding ORR activity.And investigating the function of chemical composition and pore structure of catalyst via physical and chemical characterization and electrochemical test.This paper mainly conducted the following experiments and explorations:1.Nitrogen doped porous carbon nanosheets are prepared by porolyzing the mixture of soybean dregs and g-C₃N₄,g-C₃N₄ could act as nitrogen source and additive forming pores.Via changing the ratio of soybean dregs and g-C₃N₄,the nitrogen content and pore structure of samples can be changed.Through XPS,BET characterizations,N-PC-4 shows abundant nitrogen content and large pore volume.Through the rotating disk electrode and rotating ring disk electrode test,N-PC-4 presents outstanding ORR performance,superior stability and methanol tolerance.2.Soybean dregs and g-C₃N₄ act as the precursor of nitrogen and carbon,mixed with different quality of ferrous acetate and ground uniformly,and then heated in the inert gas to obtain the crimp sheet layer with irregular pore structure.Through physical and chemical characterization,we found that iron content would affect the degree of graphitization,specific surface area and nitrogen content of the catalyst.According to the electrochemical test results,the optimized catalyst exhibits the similar ORR activity as commercial catalysts,and excellent stability and methanol resistance.3.Carbon fiber?CF?,soybean dregs?SDs?and graphitic carbon nitride?g-C₃N₄?derived carbon?denoted as CS?are used as complex carbon sources to prepare Fe and N co-doped carbon composites?Fe-N/CF-CS?,through a simple solid grinding followed by thermal decomposition,and the carbon material is composed of a sheet and a fiber.Through adjusting the proportion of CF and CS to adjust the proportion of nanosheets and fibers in the sample,and influences the morphology/structure.The optimal sample Fe-N/CF-CS-2 possesses hierarchical porous structure,high surface area,and large pore volume,which benefits the electron/mass transfer process and the exposure of more active sites,and thus exhibiting the excellent ORR activity which can compete with commercial Pt/C.Meanwhile,the catalyst also presents superior methanol resistance and long term stability in ORR process.