Metal Phthalocyanine As Model Of M-N-C Atomically Dispersed Catalystic Site For The Exploration Of Orr And NRR Mechanism

In today's society,energy and environmental issues are increasingly prominent,and the development of new energy storage and conversion devices has become an urgent issue.Electrocatalytic reactions are gaining more and more attention as a new technical means to achieve this purpose,such as oxygen reduction reaction?ORR?,oxygen evolution reaction?OER?,nitrogen reduction reaction?NRR?and so on.At present,most of these basic reactions rely on precious metals?Pt,Au,Pd,etc.?as catalysts.The high cost and scarcity limit the further development of the research.Finding alternative catalysts has become a hot topic.Phthalocyanine molecules have a clear metal-nitrogen-carbon?M-N-C?structure,and there are abundant free electrons in the macrocycle,which is conducive to the occurrence of catalytic reactions.The metal center is easy to replace and exists in the form of MN₄,which is an ideal model for electrocatalysis research.In this paper,metal phthalocyanine compounds are used as models to study the mechanism of metal-nitrogen-carbon atomic-level catalytic sites in oxygen reduction and nitrogen reduction.The specific works are as follows:?1?Boosting defective carbon by anchoring well-defined atomically dispersed metal-N₄sites for ORR,A non-pyrolytic strategy was developed to synthesize atomically dispersed M-N-C catalyst by coordinating a well-structured MN4 organic macrocyclic molecule?Fe Pc?with an N-doped site to a defective carbon nanosheet?Fe Pc@N,P-DC?.The catalyst exhibits enhanced catalytic ORR activity superior to N,P-DC and even Pt/C catalysts in half-wave potential and durability.DFT calculation results showed that the introduction of Fe Pc molecules reduced the ORR overpotential?0.80-0.52 V?of N,P-DC.?2?Bifunctional iron-phtalocyanine metal-organic framework catalyst for ORR,OER and rechargeable zinc-air batteryMelt polymerization method was used to synthesize iron polyphthalocyanine metal organic framework?MOF?coated with carbon black matrix?FePPc@CB?.Through non-covalent?-?interaction,FePPc molecules can be adsorbed on the carbon matrix,thereby promoting the electron transfer process and stabilizing the structure.Due to the abundant free electrons and atomically dispersed MN₄ catalytic sites in the macrocyclic structure,FePPc@CB showed excellent ORR activity with E_1/2 of 0.908V and j _L of 5.38 m A cm^-2.In addition,the?E values of ORR and OER are 0.68 V,making FePPc@CB catalyst a potential catalyst for liquid and solid state rechargeable zinc air batteries?ZAB?.?3?Fe/Mo bimetal polyphthalocyanine/Ketjen black composites for the research of NRR properties.A bimetal polyphthalocyanine?Fe Mo PPc?was synthesized by the melt polymerization method and based on Ketjen Black?KB?,which has excellent conductivity and high specific surface area.Among them,the metal atoms all exist in the form of Fe N₄ and Mo N₄,which are the active sites of the NRR reaction.The framework of polyphthalocyanine can provide abundant free electrons,and at the same time bring a larger density of active sites,which is more conducive to the occurrence of catalytic processes.In the end,we achieved a Faraday efficiency of 11.5%and an ammonia production rate of 33.44 mg h^-1 mg^-1_cat,which is better than most non-precious metal catalysts reported.