Preparation Of Sulfur/Phosphorus Doped Iron Carbon Nitrogen Based Oxygen Reduction Catalyst And Performance Of Zinc Air Battery

At present,the excessive use of fossil fuels has caused a series of serious energy and environmental problems.To address these issues,more efficient and environmentally friendly energy conversion and storage technologies need to be developed.Rechargeable zinc-air battery is considered as one of the most promising energy storage technologies due to their high energy density,safe use and low cost.However,its efficacy is severely limited by the kinetically sluggish oxygen reduction reaction（ORR）.To solve this problem,noble metal Pt-centered catalysts have been developed to enhance the rate of the ORR.Regrettably,Pt-based catalysts have limitations such as high cost,poor stability,and low reserves,making it difficult for Zn-air batteries to be used on a large scale in practice.Therefore,the development of non-precious metal-based catalysts with low cost,high stability and methanol resistance has become the main research direction.Iron carbon nitrogen-based catalysts have become one of the main materials to replace Pt-based catalysts due to their low price and high catalytic activity.However,the insufficient stability of iron-carbon nitrogen-based catalysts in Zn-air batteries hinders their application and development.This paper attempts to solve the stability problem encountered in the development of non-precious metal electrocatalytic materials.It is modified by introducing heteroatoms（sulfur,phosphorus）into the iron carbon-nitrogen-based catalytic material system,and prepared by adjusting the reaction conditions.Two types of materials（ten examples in total）,from which two examples of catalytic materials with excellent catalytic activity and high stability were screened,which provided experimental support for the development of iron-carbon nitrogen-based catalytic materials.The main research contents are as follows:（1）A supramolecular polymer（MCA）was prepared from melamine and cyanuric acid under certain conditions.The polymer was used as a carbon nitrogen based template,Fe Cl₃ and thiourea were introduced as Fe and S sources,and Fe CNS catalyst was prepared under the protection of 900℃and N₂.The catalysts were characterized by XRD,XPS,SEM and TEM,which proved that Fe₃N is an important active site of the catalyst,which affects the performance of the catalyst.The relevant electrochemical tests were carried out on the catalyst.The results showed that when the mass of thiourea introduced was 300mg,the catalyst performance reached the best,and its half-wave potential(E_1/2)was 0.853V,which was higher than that of commercial Pt/C catalysts.out 10m V.The zinc-air battery composed of catalysts was tested for related performance,and it was found that its power density reached 102.8m W cm^-3,which was better than 88.1m W cm^-3 of commercial Pt/C.The 150h charge-discharge test remains stable.（2）Using polyethylene glycol（PEG）2000 as a soft template and melamine,melamine phosphate and Fe（NO）₃ as precursors,Fe CNP catalysts were prepared at 900°C under N₂ protection.It was analyzed by XRD,XPS,SEM and TEM series of characterizations,and the results showed that Fe P,as the main active site of the catalyst,played a key role in its catalytic performance.The catalyst was then electrochemically tested.The test results showed that when the phosphorus doping amount was 300 mg,the catalytic performance reached the best,and its half-wave potential reached 0.82 V,which was very close to the half-wave potential of commercial Pt/C.In the test of zinc-air battery,the power density of catalyst Fe CNP-300 reached 151.6m W cm^-3,which was about70m W cm^-3 higher than that of commercial Pt/C,which was 88.1m W cm^-3,and at 10m A cm^-1,the charge-discharge test can be performed continuously for 600h,and it remains stable,which is much higher than the charge-discharge stability time of commercial Pt/C 40h.