Research On The Binary Ligand Strategy And Performance For Bifunctional Oxygen Electrode Catalysts

New energy devices,such as Zn-air batteries and fuel cells,have been widely favored by scholars on account of their high efficiency,long-term durability and eco-friendly.Oxygen reduction reaction(ORR),as one of the most significant reactions,has the sluggish kinetics,which greatly limited the extensive application of these new energy equipment.Up to now,the precious metal Pt-based/Ir-based catalysts with the excellent electrochemical performance are no longer suitable for oxygen reduction reaction and oxygen evolution reaction due to the fewer resources and high cost.Therefore,developing high-efficiency oxygen reduction electrocatalysts that can replace precious metals are imminent.Based on these,through the binary ligand strategy,this article synthesizes a series of carbon-based bimetallic doped catalysts with hierarchical pore structure,high activity and durability.The main research contents are as follows:(1)Via the binary ligand strategy,we synthesized the FeNi co-doped electrocatalysts derived from metal-organic frameworks(MOFs),which possessed a large specific surface area and hierarchical microporous,mesoporous and macroporous structures.As a result,the B-FeNi-N/C-1000 exhibits an outstanding ORR performance with a half potential of 0.9 V vs RHE and a lower potential of 1.62 V at 10 mA cm-2 in alkaline media,which exceeds the unitary ligand FeNi catalyst(FeNi-N/C-1000)and Pt/C+IrO2.Additionally,in Zn-air flow battery,the B-FeNi-N/C-1000 presents a higher power density of 102 mW cm-2 and a long-term stability that only loss from 56.8%to 54.8%after 95 hours.Consequently,this work can provide a facile method to synthesize efficient bifunctional catalyst with hierarchical porous structure for promoting ORR and OER.(2)To further verify the effect of the binary ligand strategy for the ORR performance in acidic medium,we fabricated Cr doped and FeCr co-doped electrocatalyst.In 0.1 M HClO4 solution,FeCr-N/C-1000 has a superior half potential of 0.783 V vs RHE,higher than Cr-N/C-1000 and Pt/C.Furthermore,the Tafel slop and the hydrogen peroxide was the highest among these catalysts.The excellence ORR activity may be attributed to the formation of CrN during the carbonization,and metal Fe doping can enrich the d electron of Cr in CrN,thus improving the efficiency of catalyst.Additionally,the doping of metal Cr can reduce the Fenton reaction and avoid the insufficient stability.Therefore,doping dual metal via the binary ligand strategy plays a decisive role in the design and application of catalysts in the renewable energy.