Electrocatalytic Performance Of Co-based Spinel Nanofibers Bifunctional Oxygen Electrodes

In the 21st century,energy has become the key to the sustainable development of national economy security,in order to realize the sustainable development of human society in the future,how to develop and use the new clean energy storage and conversion devices has become a main research direction in the field of energy in the new century,the low-temperature fuel cell has received the widespread attention.For such energy conversion device,the oxygen reduction reaction and oxygen precipitation reaction is an important reaction in such devices,due to the above two kinds of reaction kinetics is very slow,this limits the low-temperature fuel cell commercialization,make the development of high-performance bifunctional catalyst become the main target of the researchers.In recent years,spinel oxide materials have attracted extensive attention because of its relatively low cost,easy synthesis and other advantages.In this paper,spinel-type oxide Co₃O₄/NiCo₂O₄@CoNi O₂/CuCo₂O₄@CuO was prepared by electrospinning method,and the influence of polymer concentration and electrospinning voltage on the spinning morphology was investigated.After obtaining the optimal spinning conditions,spinel-type oxide Co₃O₄/NiCo₂O₄@CoNi O₂/CuCo₂O₄@CuO nanofibers were prepared by using the conditions.The nanofibers were annealed at four different temperatures and the electrochemical properties of the nanofibers were tested using a rotating disk electrode system.In order to investigate the properties of spinel oxides prepared by electrospinning method,this paper also used sol-gel method to prepare spinel oxides Co₃O₄/NiCo₂O₄@CoNi O₂/CuCo₂O₄@CuO.The same method was used to test their electrochemical properties.As expected,due to the porous structure formed after the annealing of nanofibers,The electrochemical properties of Co₃O₄/NiCo₂O₄@CoNi O₂/CuCo₂O₄@CuO prepared by electrospinning method are better than that by sol-gel method.One of the catalyst materials treated at four different annealing temperatures was selected to undergo phosphating treatment according to the mass ratio of catalyst and phosphorus source of 1:5,1:10 and 1:20.After the phosphates were obtained,the electrochemical performance was tested using a rotating disk system.By investigating the preparation of Co₃O₄/NiCo₂O₄@CoNi O₂/CuCo₂O₄@CuO nanofibers by electrospinning,it is found that when the PVP content is 9.4 wt%/9.4wt%/16 wt%,and the applied voltage is 10k V/12k V/16k V,the spinning effect is the best.It is found that the electrochemical performance of spinel oxides prepared by electrospinning is the best for Co₃O₄,of which the electrochemical performance of Co₃O₄600 is the best compared with other temperatures,and the△E of Co3O4600 is only 1.2V,while Co₃O₄600@P1:10 of△E is only 1.19V,For NiCo₂O₄@CoNi O₂,the electrochemical performance of NCO 500 is the best compared with that of other temperatures.The△E of NCO 500 is only 1.007V,while the△E of NCO 400@P1:20 is only 1.134V（the△E of NCO 400 is 1.169V）.For CuCo₂O₄@CuO,the electrochemical performance of CCO 500 is the best compared with other temperatures.The△E of CCO500 is only 1.237V,while the△E of CCO 600@P1:10 is only 1.256V（the△E of CCO600 is 1.308V）.