Theoretical Studies On The Construction And Performance Of High Efficient Oxygen Reduction Electrocatalyst

The increasingly environmental pollution and the growing consumption of fossil fuels have been important topics for scientists to search clean,efficient,sustainable energy.Fuel cells have attracted the attention of the researchers,because it's excellent properties and good application prospect.Although fuel cells have excellent properties,it does not have a large rate of practical application.This mainly because the oxygen reduction reaction in the cathode at a slower rate.We need to provide a large amount of precious metals such as Pt be a catalyst to speed up the rate.However,precious metals such as Pt are expensive,instability and make it difficult to the extensive use of Pt-based catalysts.So looking for efficient,cheap,stable electrocatalyst for oxygen reduction reaction?ORR?has always been challenge for the development of a large-scale application for fuel cell catalysts or metal air batteries.In this paper,through density function theory?DFT?,the geometry,electronic structure,and catalytic performance were systematically studied for two different two-dimensional materials.Details are as follows:?1?We systematically investigated the potential of the experimentally synthesized two-dimensional?2D?metal–tetracyanoquinodimethane?M–TCNQ,where M denotes Mn,Fe,and Co?monolayers as novel ORR catalysts by means of density functional theory?DFT?computations.Our results revealed that O₂ molecules can be chemisorbed and efficiently activated on the M–TCNQ monolayers and this will activate the O-O chemical bond of O₂.The activated O₂ subsequent will be reduced into H₂O or OH^-,this reaction can readily proceed via a 4e^-pathway.Remarkably,by compare the catalytic with these three monolayers,the Fe–TCNQ monolayer exhibits the highest catalytic activity,in both acidic and alkaline media.Furthermore,we found that the electrocatalytic performance could be further enhanced by attach axial halogen ligands to the M of M–TCNQ monolayers.Therefore,the Fe–TCNQ monolayer might serve as a promising alternative to Pt-based catalysts for the ORR.?2?In this work,we have systemically explored the anchoring of Organic macrocyclic molecules Co?acac?₂?acac=acetylacetonate?on N-doped graphene nanoribbon and its potential as the ORR electrocatalyst.Our DFT computations revealed that N-doped graphene nanoribbon can be used as the anchoring material of the Co?acac?₂ complex due to the formation of a Co–O₄–N moiety,thus ensuring its high stability.We found that an O₂ molecule can be moderately activated on the surface of the anchored Co?acac?₂ complex and the O-O of O₂ would be activated,the subsequent ORR steps prefer to proceed though a more effcient 4 e^-pathway with a small overpotential?0.67 e V?.As a result we found that the hybridization of Co?acac?₂ with N-doped graphene can effective catalytic ORR in fuel cells.In this paper,we systematically analyzed the stability and catalytic performance of M–TCNQ and Co?acac?₂ with N-doped graphene,the results indicated these materials as catalysts for ORR.Our results provide theoretical foundation and clues for experimentally synthesized,low and high efficiency non-metallic catalysts.