Metal-organic-framework (MOF) Derived Non-Precious Electrocatalysts For Oxygen Reduction Reaction

The oxygen-reduction reaction(ORR)is a critical process for fuel cells and metal–air batteries(excellent conversion efficiency,high energy capacity,and low environmental impact).Therefore,the development of electrocatalysts for the ORR is of essential importance.The boosted activity of catalysts is usually attributed to the high surface areas,the unique facet structures,the superior conductivities,or even to imprecise synergistic effects of metals.Therefore,it is feasible to improve the activity of oxygen reduction catalysts by optimizing these factors.The newly emerging metalorganic frameworks(MOFs)are widely used as sacrificial precursors/templates to fabricate heteroatom-doped nanostructured porous carbon materials having characteristics such as high surface areas,permanent and uniform porosities and controllable functionalities that enable their good performance to exhibit superior catalytic activity that was difficult to obtain using conventional methods.We have reported synthesis and electrocatalytic activity of MOF-derived,heteroatom-doped(N,Fe,Mn and Co)porous carbon nanostructured electrocatalysts for ORR in alkaline and acidic solutions.We have successfully developed several catalysts with high surface area and mesoporous structure by employing MOFs as the precursors which could not only provide many active sites but also leave many channels for mass transfer after calcination.The emphasis is placed on the metal-activity relationship of MOF-derived transition-metal-doped carbon catalysts.Furthermore,we also studied the synergistic effect of different metals after the pyrolysis,and finally on elecrocatalytic activity for ORR.For this purpose,several bimetallic/trimetalic(with different metal ratios)MOF precursors were synthesized and then calcined at elevated temperatures to transform into ORR catalysts.The discussion provides a useful strategy for template free synthesis of heteroatom-doped carbon ORR electrocatalysts by rationally designing MOF precursors.Due to the versatility of MOF structures,MOF-derived porous carbons provide chances to develop highly efficient ORR electrocatalysts.