Effective Oxygen Electrode Bifuntional Electrochemical Catalyst Derivered From MOF Precursor

Fuel cells can directly convert chemical energy into electrical energy with high conversion efficiency,high durability and low population,which has potential to be widely used in power station,electric vehicle and aerospace fields Up to date,Pt-based materials are still mostly used as catalyst in commercial fuel cells.Yet,Pt has low reserve and high price therefore it can’t sustain the large scale application of fuel cell.Hence it is of great interst and important to develop novel candidates to replace Pt-based electrocatalysts for the commercial application of fuel cells.Based on Fe/Co-N-C unprecious active center’s high bifunction performance,here,we designed and prepared Fe/Co-N-C bifunction oxygen electrode catalysts with different metal ratios from MOF precursors,then estimated their activity and stability in alkaline electrolyte,and finally revealed the relationship between structural properties and electrochemical performance.This work will contribuate to development of novel high-performance non-precious metal electrocatslyst to oxygen electrode reactions.The main work was expounded below:(1)A series of Fe/Co bimetal MOFs were controllably synthesized with different Fe/Co ratios using FeCl3,Co(OOCCH3)2 and p-phthalic acid as the feeding chemicals by solvothermal menthod.After calcining with melamine as the nitrogen source,we successfully obtained N-doped materials with Fe/Co-N-C double active centers.Then we analyzed the influence of Fe/Co ratio on morphography,active species and activity.Fe3/Co1-N-C derived from Fe/Co=3 MOF had the largest carbon nanotube and structure defect number,highest surface N content and largest surface area,which exhibited the best electrocatalyst performance with the smallest potential gap of 0.814 V between the OER potential at 10 mA cm-2 and the ORR half-wave potential.Also,this catalyst showed the promising stability with the half-wave deterioration of 12 mV after 5000 CV cycles.(2)A series of Co/Zn bimetal MOFs as the precursors were synthesized by one-step solvothermal menthod using Zn(N03)2,Co(OOCCH3)2,p-phthalic acid and melamine as the feeding chemicals.Then Zn was removed at high temperature to aquire Co-N-C active center and Co nanoparticle loaded bifunction oxygen electrode catalysts.Furtheremore,we systematicly examined the influence of Co/Zn ratios on morphography,active species and activity.Among the investigated catalysts,Co-1/2-N-C with Co/Zn=1 raio precursor demonstrated the best bifuntion electrocatalytic performance with the potential gap of 0.814 V between the OER potential at10 mA cm-2 current density and the ORR half-wave potential.