Preparation Of Iron-based Catalyst By Plasma And Its Electrochemical Performance

Cold plasma,with its unique high-energy electron bombardment,active particle bombardment and low-temperature treatment characteristics,can achieve the effect that conventional means cannot achieve in the preparation and synthesis of catalyst.Under the influence of plasma,the nucleation and crystal growth in the process of catalyst preparation is quite different from that in the conventional heat treatment.In addition,cold plasma has been widely used in catalyst surface treatment or modification.The results of this treatment include the generation of surface vacancy,defects,doping and rough surface,the increase of active center and the modification of surface functional groups.Cold plasma surface treatment is a fast and effective method to change the catalyst surface.It was found that plasma treatment plays an important role in the modification of catalyst morphology and structure.On the basis of previous research,the influence of dielectric barrier discharge plasma on the size and structure of iron-based catalyst and the mechanism of improving the performance of catalyst were discussed.The main contents of this paper are as follows:（1）FeOx-D obtained by treating iron nitrate with dielectric barrier discharge plasma technology has excellent catalytic performance for oxygen reduction reaction（ORR）.According to the TEM characterization results,the Fe Ox-C sample obtained by calcination method has large particle size（40 nm）and agglomeration,while Fe Ox-D sample has small particle size（13 nm）and good dispersion.According to XPS,O₂-TPD and BET characterization results,compared with Fe Ox-C,Fe Ox-D surface has the structural characteristics of coexistence of multivalent Fe,large amount of oxygen vacancy,strong oxygen adsorption capacity and large specific surface area,which makes it show excellent ORR catalytic performance.The specific performance is:the peak current density of Fe Ox-D sample is large,and the peak potential is shifted by 60 m V.The Fe Ox-D transfer electron number of sample is 3.83,which is close to the theoretical value.It is proved that the plasma treatment improves the intrinsic activity of iron oxide.（2）The preparation of Fe-Co bimetallic oxides by plasma and the study of their ORR and OER bifunctional catalytic properties.The high conductivity carbon black XC-72R is used as the conductive substrate,on which iron nitrate and cobalt nitrate are impregnated as the precursor.Using dielectric barrier discharge plasma technology and high temperature calcination to treat precursor to obtain loaded Fe Ox/Co Oy@C-D and Fe Ox/Co Oy@C-C catalyzer.The effect of the ratio of Fe to Co atoms on the catalytic performance of the catalyst was also discussed.It was found that the Fe Ox Co Oy@C-D composite was prepared by plasma method when the ratio of Fe to Co atoms was 1:3.At this time,the potential difference between ORR and OER is only 0.89 V.The study also found that compared to Fe Ox/Co Oy@C-C,Fe Ox/Co Oy@C-D have stronger catalytic performance.To sum up,this paper focuses on the preparation of iron-based catalysts by plasma method,aiming to improve the catalytic activity of transition metal oxides.The iron oxide prepared by plasma method has stronger electrocatalytic performance than that by high temperature roasting method.On this basis,Fe-Co bimetallic oxides with high conductivity carbon black as support were prepared.The Fe-Co bimetallic oxide composite prepared by plasma method has excellent bifunctional electrocatalytic activity close to commercial catalyst.